Glossary of technical terms for the use of metallurgical engineers Terms starting with alphabet ‘C’
Glossary of technical terms for the use of metallurgical engineers
Terms starting with alphabet ‘C’
Cable – It is a line made of rope, chain or wire which has different functions as per the application it is used for. It can either tie together two points or simply connect them, as in electricity conveyance or data transmission, and can be load bearing or non-load bearing.
Cable assembly drawing – It depicts an electrical cable assembly of defined length and establishes item identification for that assembly. It is prepared to describe power, signal, radio frequency, audio and general-purpose electrical cable assemblies including both single-run and branched cables. It includes (i) dimensions and tolerances for overall length and breakout locations, (ii) identification of parts, bulk materials, and processes required for fabrication of the cable assembly, (iii) preparation of the cable ends, (iv) orientation and offset of connectors, (v) maximum diameter of cable, (v) minimum bend radii for wiring within the assembly, (vi) detail views of moulded areas, (vii) conductor lay patterns, (viii) identification band or other marking requirements, (viii) a wiring list, wiring diagram, or schematic diagram, (ix) finish, special assembly, and/or storage instructions and (x) test requirements.
Cadmium – It is a soft, malleable, ductile, silvery white di-valent metal found in zinc ores, and to a much lesser extent, in the cadmium mineral greenockite. It is similar in several respects to zinc but forms complex compounds.https://en.wikipedia.org/wiki/Cadmium#cite_note-Holl-9 Unlike majority of other metals, cadmium is resistant to corrosion and is used as a protective plate on other metals. As a bulk metal, cadmium is insoluble in water and is not flammable, however, in its powdered form it can burn and release toxic fumes.
Cadmium plating – Electro-deposits of cadmium are used to protect steel and cast iron against corrosion. Since cadmium is anodic to iron, the underlying ferrous metal is protected at the expense of the cadmium plate even if the cadmium becomes scratched or nicked, exposing the substrate. Cadmium is normally applied as a thin coating (less than 25 micrometers thick) intended to withstand atmospheric corrosion. It is seldom used as an undercoating for other metals, and its resistance to corrosion by most chemicals is low.
Caesium-137 (Cs-137) – It is a radioactive isotope of caesium which is formed as a fission product by nuclear fission. In small amounts it can be used to calibrate radiation-detection equipment. Caesium shares similar chemical properties to other Group 1 elements including sodium and potassium. If ingested, Cs-137 is distributed fairly uniformly throughout the body’s soft tissue, resulting in exposure of those tissues which can be treated with Prussian Blue (Ferric Hexacyanoferrate). The magnitude of the health risk depends on exposure conditions. These include factors such as strength of source, length of exposure, distance from the source, and whether there was shielding between the tissue and the source (such as metal plating).
Cage – It is a part of the valve trim which surrounds the closure member and can provide flow characterization and / or a seating surface. It also provides stability, guiding, balance, and alignment, and facilitates assembly of other parts of the valve trim. The walls of the cage contain openings which normally determine the flow characteristic of the valve. In a bearing, it is a device which partly surrounds the rolling elements and travels with them, the main purpose of which is to space the rolling elements in proper relation to each other.
Cake – It is a copper or copper alloy casting, rectangular in cross section, used for rolling into sheet or strip. It is also a coalesced mass of unpressed metal powder.
Calcareous coating or deposit – It is a layer consisting of a mixture of calcium carbonate and magnesium hydroxide deposited on surfaces being cathodically protected against corrosion, because of the increased pH adjacent to the protected surface.
Calcination – It consists of heating ores, concentrates, precipitates, or residues to decompose carbonates, hydrates, or other compounds. The calcination process needs heating a material to a high temperature with the intent of chemical dissociation (chemical separation). The process is used for the calcination of limestone, dolomite, and magnesite.
Calcium – It is a metallic chemical element of the alkaline-earth group having atomic number 20 and atomic weight 40.08. Calcium additions are made during steel making for refining, deoxidation, desulphurization and for the control of shape, size and distribution of oxide and sulphide inclusions. Calcium is not used as alloying element since its solubility in steel is very low.
Calcium carbide – It is also known as calcium acetylide, is a chemical compound with the chemical formula of CaC2. Its main use is in the production of acetylene. In steel industry, it is used for desulphurization and de-oxidation.
Calcium di-silicide (CaSi2) – It is an inorganic compound, a silicide of calcium. It is a whitish or dark grey to black solid matter with melting point 1033 deg C. It is insoluble in water, but can decompose when subjected to moisture, evolving hydrogen and producing calcium hydroxide. It is used both in the form of powder and lumps in iron and steel industry as a powerful deoxidizer and desulphurizer, owing to the high affinity of calcium, for oxygen, sulphur and other elements.
Calcium fluoride (CaF2) – Calcium fluoride is the inorganic compound of the elements calcium and fluorine with the formula CaF2. It is a white solid that is practically insoluble in water. It occurs as the mineral fluorite (also called fluorspar), which is often deeply coloured owing to impurities. Metallurgical grade fluorites with 60 % to 85 % CaF2 content are used to reduce slag surface pressure in steel production, to reduce melting temperature and slag viscosity.
Calcium fluoride coating – This type of electrode coating provides shielding gas to protect the arc, adjusts the basicity of the slag, and provides fluidity and solubility of the metal oxides.
Calcium silicon – It is also called calcium silicide. It is an alloy of calcium, silicon, and iron containing 28 % to 35% calcium, 60 % to 65 % silicon, and 6 % maximum Fe (iron). It is used as a deoxidizer and degasser for steel and cast iron.
Calender – It is the passing of plastic sheet material between sets of pressure rollers to produce a smooth finish and a desired thickness.
Calibrated iron ore – It is the sized iron ore normally in the size range of 10 mm to 30 mm.
Calibration – The process of comparison against a ‘standard’ and making the necessary adjustments is normally called calibration. Detailed records are maintained for each item which is calibrated to ensure ‘traceability’, and that the item meets clearly identified specifications for both accuracy and precision in all its operating parameters. Calibration refers to the process of setting the magnitude of the output (or response) of a measuring instrument to the magnitude of the input property or attribute within specified accuracy and precision.
California bearing ratio – It is a measure of the strength of the subgrade of a road or other paved area, and of the materials used in its construction. The ratio is measured using a standardized penetration test.
Calomel electrode (Calomel half-cell) – Calomel electrode is half-cell containing a mercury electrode in contact with a solution of potassium chloride of specified concentration that is saturated with mercurous chloride (calomel). This electrode is widely used as a reference electrode of known potential in electrometric measurement of acidity and alkalinity, corrosion studies, voltammetry, and measurement of the potentials of other electrodes. It is also a secondary reference electrode of the composition: Pt/Hg-Hg2Cl2/KCl solution. For 1 N KCl solution, its potential against a hydrogen electrode at 25 deg C and 0.1 MPa is +0.281 V (volts).
Calorie – It is a unit for measuring a quantity of heat and is the quantity of heat needed to increase the temperature of a gram of water by one deg C. The mean calorie is 1/100 of the heat needed to raise the temperature of 1 gram of water from 0 deg C to 100 deg C at a constant atmospheric pressure. A calorie is 4.184 joules.
Calorific value – It refers to the energy content of a fuel, representing the net heat released by a unit quantity of fuel during combustion in the presence of oxygen. It is a crucial factor impacting the furnace performance and efficiency, with gross and net calorific values being the two main types used to measure this energy content.
Calorimeter – It is the apparatus for determining the calorific value of a fuel.
Calorizing – It consists of imparting resistance to oxidation to an iron or steel surface by heating in aluminum powder at 800 deg C to 1,000 deg C.
Cam – It is a rotating or sliding piece in a mechanical linkage used especially in transforming rotary motion into linear motion. It is frequently a part of a rotating wheel (e.g. an eccentric wheel) or shaft (e.g. a cylinder with an irregular shape) that strikes a lever at one or more points on its circular path.
Camber – It is deviation from edge straightness, normally referring to the highest deviation of side edge from a straight line. It is also the tendency of material being sheared from sheet to bend away from the sheet in the same plane. Sometimes the term is used to denote crown in rolls where the centre diameter has been increased to compensate for deflection caused by the rolling pressure. It also denotes the planar deflection of a flat cable or flexible laminate from a straight line of specified length. A flat cable or flexible laminate with camber is similar to the curve of an unbanked race track. In rolled metal, camber is a curve across the plane of the sheet, whether down the middle or along one or both edges. Camber is measured by putting a straight edge next to the sheet. The greatest distance between the straight line and the sheet’s curve is the camber. A cambered sheet might be slightly thinner in the middle than on the edges (concave), thicker in the middle (convex), or thinner on one side (triangular).
Cam press – It is a mechanical forming press in which one or more of the slides are operated by cams. It is normally a double-action press in which the blank holder slide is operated by cams through which the dwell is obtained.
Can – It is a sheathing of soft metal that encloses a sintered metal billet for the purpose of hot working (hot isostatic pressing, hot extrusion) without undue oxidation.
Canning – It is a dished distortion in a flat or nearly flat sheet metal surface, sometimes referred to as oil canning. It also means enclosing a highly reactive metal within a relatively inert material for the purpose of hot working without undue oxidation of the active metal.
Cantilever roll stands – Cantilever roll stands are compact stands which are used in a wide range of sizes for a variety of applications. These applications include (i) single strand mills in horizontal and vertical arrangement, (ii) in split intermediate trains of two or more strands mills, and as pre-finisher stands in wire rod delivery sections. The advantages of these stands include (i) smaller foundations, (ii) cassettes of the same stand type are interchangeable even between horizontal and vertical stands, (iii) high load bearing strength even with small diameters hence ideally suited for high-speed wire rod blocks, (iv) optimum accessibility, and (v) fast roll and stand changing.
Cantilever spring – This is a type of spring which is fixed only at one end.
Cap or plug – It is a type of pipe fitting which is liquid or gas tight, and is used to cover the end of a pipe. A cap has a similar function to a plug. For screwed systems the cap is having female threads where a plug is having male threads.
Capacitor discharge stud welding – Capacitor discharge stud welding is a stud arc welding process in which the tip of the stud melts almost instantly when energy stored in capacitors is discharged through it. The three basic modes of capacitor discharge stud welding are initial-gap welding, initial-contact welding, and drawn-arc welding.
Capacity – It is the quantity of flow through a valve, under stated conditions.
Capacity factor – It is the ratio of the average load carried to the maximum design capacity.
Capacity number – It is the product of the Sommerfeld number and the square of the length-to-diameter ratio of a journal bearing
Capillary action – It is the phenomenon of intrusion of a liquid into interconnected small voids, pores, and channels in a solid, resulting from surface tension. It is the force by which liquid, in contact with a solid, is distributed between closely fitted faying surfaces of the joint to be brazed or soldered.
Capillary attraction – It is the combined force of adhesion and cohesion which causes liquids, including molten metals, to flow between very closely spaced and solid surfaces, even against gravity. In powder metallurgy, it is the driving force for the infiltration of the pores of a sintered compact by a liquid.
Capital repairs – Capital repairs of are those repairs which are taken up after the end of a campaign of the blast furnace. During the capital repairs, the main jobs which are normally taken up are (i) relining of the furnace, (iii) repairs of the damaged portion of the shell, (iii) major revisioning of all the equipment with replacement of the worn out components, (iv) replacement of those equipments, instruments, and automation items which have become obsolete or completed their useful life, and (v) modification work the need of which was felt during the running of the blast furnace in the campaign which has just ended.
Capital spares – These are critical spares and are usually replaced during the capital repair of the equipment. Hence the procurement action and receipt of these spares are to be planned at the time of taking up of the equipment for the capital repair.
Capped steel – It is a type of steel similar to rimmed steel, normally cast in a bottle-top ingot mould, in which the application of a mechanical or a chemical cap renders the rimming action incomplete by causing the top metal to solidify. The surface condition of capped steel is much like that of rimmed steel, but certain other characteristics are intermediate between those of rimmed steel and those of semi-killed steel. The rimming action can be arrested mechanically by putting a heavy steel plate on the top of the surface of the ingot (mechanical capping) or can be stopped by killing by the addition of deoxidizers on the ingot top (chemical capping). The rimming action can also be stopped by spraying water on the top of the ingot.
Capping – It means partial or complete separation of a powder metallurgy compact into two or more portions by cracks which originate near the edges of the punch faces and that proceed diagonally into the compact. In case of abrasive particles, capping is a mechanism of deterioration of abrasive points in which the points become covered by caps of adherent abrasion debris.
Capture efficiency – In friction lubrication, it is the cross-sectional area of undisturbed fluid containing particles which ultimately impinges on a given solid surface, divided by the projected area of the solid surface.
Carbide – It is a compound of carbon with one or more metallic elements.
Carbide tools – It is the cutting or forming tools, normally made from tungsten, titanium, tantalum, or niobium carbides, or a combination of them, in a matrix of cobalt, nickel, or other metals. Carbide tools are characterized by high hardnesses and compressive strengths and can be coated to improve wear resistance.
Carbolic oil – It is also known as light oil and is a complex combination of hydrocarbons obtained by distillation of coal tar. It consists of aromatic and other hydrocarbons, phenolic compounds and aromatic nitrogen compounds and distills at the approximate temperature range of 150 deg C to 210 deg C.
Carbon – It is a non-metallic chemical substance. Carbon has a major effect on steel properties. It is the primary hardening element in steel. Hardness and tensile strength increase as the carbon content increases up to around 0.85 %. Ductility and weldability decrease with increase of the carbon content. Carbon is essential in steels which have to be hardened by quenching.
Carbonaceous – It is a material which contains carbon in any or all of its several allotropic forms.
Carbon arc brazing – It is a brazing process which produces coalescence of metals by heating them with an electric arc between two carbon electrodes. The filler metal is distributed in the joint by capillary action.
Carbon arc cutting -It is an arc cutting process in which metals are severed by melting them with the heat of an arc between a carbon electrode and the base metal.
Carbon arc welding – It is an arc welding process which produces coalescence of metals by heating them with an arc between a carbon or a graphite electrode and the work. No shielding is used. Pressure and filler metal can or cannot be used. This electrode erodes fairly quickly and generates carbon mono-oxide gas which partially replaces the air around the arc, thereby providing the molten weld with some protection.
Carbon blocks – These are refractories made of carbon and are used for lining of hearth bottom and hearth walls.
Carbon bonded dolomite bricks – Dolomite bricks are also made in carbon-bonded compositions. The carbon-bonded varieties include both pitch and resin-bonded alternatives. Some of the carbon-bonded bricks contain flake graphite and are somewhat analogous to magnesite-carbon brick.
Carbon capture and storage – It is also called sequestration. It involves the capture, transport, injection and containment of carbon di-oxide in geological structures such as depleted oil and gas reservoirs, onshore and offshore saline aquifers located deep in the earth’s crust, salt caverns or unmineable coal beds. It is both an approach to enhance production from existing oil and gas operations as well as a means for reducing green-house gas emissions. Carbon capture and storage provides an additional alternative in the utilization of fossil-fuel based energy, while providing additional transition time for energy systems to move towards carbon reduced or zero carbon fuels, such as renewables.
Carbon di-oxide – Carbon di-oxide is a chemical compound. It is made up of molecules that each have one carbon atom covalently double bonded to two oxygen atoms. It does not burn, and in standard temperature and pressure conditions it is stable, inert, and non-toxic. It is a green-house gas.
Carbon di-oxide process – It is a process for hardening moulds or cores in which carbon di-oxide gas is blown through dry clay-free silica sand for precipitating silica in the form of a gel from the sodium silicate binder.
Carbon di-oxide welding – It is a non-standard term for gas metal arc welding which is an arc welding process that produces coalescence of metals by heating them with an arc between a continuous filler metal electrode and the work-pieces. Shielding is done entirely from an externally supplied gas.
Carbon edges – These are carbonaceous deposits in a wavy pattern along the edges of a steel sheet or strip. It is also known as snaky edges.
Carbon electrode – It is a non-filler material electrode used in arc welding or cutting, consisting of a carbon or graphite rod, which can be coated with copper or other coatings. The carbon electrodes are of three grades namely (i) plain, (ii) uncoated, and (iii) copper coated. Applications include carbon arc welding, twin carbon arc welding, carbon cutting, and air carbon arc cutting and gouging.
Carbon equivalent (CE) – For cast iron, it is an empirical relationship of the total carbon, silicon, and phosphorus contents expressed by the formula given be equation CE = %C + 0.3(%Si) + 0.33(%P) – 0.027(%Mn) + 0.4(%S). For determination of weldability. Carbon equivalent is expressed by equation CE = C + Mn/6 + Ni/i5 + Cu/15 + Cr/5 + Mo/5 + V/5.
Carbon flotation – It is the free graphite which has separated from the molten iron in a cast iron. This imperfection tends to occur at the upper surfaces of the cope of castings.
Carbo-nitriding – It is a case-hardening process in which a suitable ferrous material is heated above the lower transformation temperature in a gaseous atmosphere of such composition as to cause simultaneous absorption of carbon and nitrogen by the surface and, by diffusion, create a concentration gradient. The heat-treating process is completed by cooling at a rate which produces the desired properties in the work-piece. Carbo-nitriding is used mainly to impart a hard, wear-resistant case, normally from 0.075 mm to 0.75 mm deep. A carbonitrided case has better hardenability than a carburized case (nitrogen increases the hardenability of steel, it is also an austenite stabilizer, and high nitrogen levels can result in retained austenite, particularly in alloy steels). Consequently, by carbo-nitriding and quenching, a hardened case can be produced at less expense within the case-depth range indicated, using either carbon or low-alloy steel. Full hardness with less distortion can be achieved with oil quenching, or, in some cases, even gas quenching, using a protective atmosphere as the quenching medium.
Carbonization – It is the high-temperature conversion of an organic substance into elemental carbon. In coke making, carbonization is a process in which coal is heated in the absence of oxygen. After combustion, carbonization of coal is the most important use of coal to produce coke.
Carbonizing flame -It is the reducing flame.
Carbonization of coal – It is also known as coking of coal. The process consists of thermal decomposition of coals either in the absence of air or in controlled atmosphere to produce a carbonaceous residue known as coke.
Carbon manganese steels – These steels refer to a family of medium to high strength steels which through a combination of correct selection of chemical composition and hot rolling mill processing parameters produce products with enhanced formability and toughness. The Mn content in these steels is increased for the purpose of increasing depth of hardening and improving strength and toughness. C steels containing higher than 1.2 % and up to around 1.8 % Mn are referred to as carbon manganese steels.
Carbon mono-oxide – Carbon mono oxide is a poisonous, flammable gas which is colourless, odourless, tasteless, and slightly less dense than air. Carbon mono-oxide consists of one carbon atom and one oxygen atom connected by a triple bond. It is the simplest carbon oxide. It is predominantly produced by incomplete combustion of carbon-containing materials.
Carbon potential – It is a measure of the ability of an environment containing active carbon to alter or maintain, under prescribed conditions, the carbon level of a steel. In any particular environment, the carbon level attained depends on such factors as temperature, time, and steel composition.
Carbon refractories – These refractories mainly consist of carbon. These refractories are frequently used in highly reducing environments, and their properties of high refractoriness allow them excellent thermal stability and resistance to slags. These are widely used in blast furnace hearth lining.
Carbon restoration – It consists of replacing the carbon lost in the surface layer from previous processing by carburizing this layer substantially to the original carbon level. It is sometimes called recarburizing.
Carbon steel – It is the steel having no specified minimum quantity for any alloying element, other than the normally accepted quantities of manganese (1.65 %), silicon (0.6 %), and copper (0.6 %), and containing only an incidental quantity of any element other than carbon, silicon, manganese, copper, sulphur, and phosphorus. Low-carbon steels contain up to 0.3 % C, medium-carbon steels contain from 0.3 % C to 0.6 % C, and high-carbon steels contain from 0.6 % C to 1 % C.
Carbonyl powder -It is the metal powders prepared by the thermal decomposition of a metal carbonyl compound such as nickel tetracarbonyl Ni(CO)4 or iron pentacarbonyl Fe(CO)5.
Carburizing – It is the absorption and diffusion of carbon into solid ferrous alloys by heating, to a temperature normally above Ac3 transformation temperature, in contact with a suitable carbonaceous material. A form of case hardening which produces a carbon gradient extending inward from the surface, enabling the surface layer to be hardened either by quenching directly from the carburizing temperature or by cooling to room temperature, then re-austenitizing and quenching.
Carburizing flame – It is a gas flame which introduces carbon into some heated metals, as during a gas welding operation. A carburizing flame is a reducing flame, but a reducing flame is not necessarily a carburizing flame.
Carburizing steel – Carburizing steels normally have base carbon contents of around 0.2 %, with the carbon content of the carburized layer normally being controlled in the range of 0.8 % to 1 %. However, surface carbon is frequently limited to 0.9 % because too high a carbon content can result in retained austenite and brittle martensite, Carburized steel consists of a composite material, where the carburized surface is hard but the unaffected core is softer and ductile. Compressive residual stresses are formed in the surface layer upon quenching from the carburizing temperature. The combination of high hardness and compressive stresses results in high fatigue strength, wear resistance and toughness.
Carcass – The reinforcement found on the inside of a conveyor belt is normally referred to as the carcass or carcase. In a sense, the carcass is the heart of the conveyor belt since it (i) provides the tensile strength necessary to move the loaded belt, (ii) absorbs the impact of the impinging material being loaded onto the conveyor belt, (iii) provides the bulk and lateral stiffness needed for the load support, and (iv) provides adequate strength for proper bolt holding and / or fastener holding.
Car furnace – It is a batch-type furnace using a car on rails to enter and leave the furnace area. Car furnaces are used for lower stress relieving ranges.
Car hearth furnaces – These furnaces have a movable hearth with steel wheels on rails. The load is placed on the car hearth, moved into and heated in the furnace and removed from the furnace on the car hearth. The car hearth is then unloaded. Cooling is done on the car hearth either in the furnace or outside before unloading. This type of furnace is used mainly for heating heavy or bulky loads, or short runs of assorted sizes and shapes. The furnace door can be affixed to the car.
Carrier – In emission spectrochemical analysis, a material added to a sample to facilitate its controlled vaporization into the analytical gap. See also analytical gap.
Carrier chain conveyor – Carrier chain conveyor consists of one or more number of endless chains to which can be attached one of the many different attachments for the purpose of carrying unit materials or objects. In several cases, the materials are conveyed while being directly in contact with the chain / chains. These conveyors have a broad application in practically all the fabricating and the processing industries. Different designs of attachments are used for different types of materials. Carrier chain conveyors are normally classified into two basic types namely (i) rolling type, and (ii) sliding type.
Carrier gas – In thermal spraying, the gas used to carry the powdered materials from the powder feeder or hopper to the gun.
Carry-over – It is the chemical solids and liquid entrained with the steam from a boiler.
Car-type conveyor – This type of conveyor consists of a series of small platform cars, propelled by an endless chain, running on a closed track. Car-type conveyors can have vertical run-arounds over sprockets having horizontal axis. However, more frequently they are designed with horizontal run-arounds (carousels) over sprockets (or sheaves for rope drive) with vertical axis. This type of conveyor is also called a carousel conveyor or a pallet-type conveyor.
Cascading bed motion – The cascading bed motion in a rotary kiln occurs because of the clustering of several particles in the upper zone under the action of the increased rotation speed. When a condition in which the height of the leading edge (shear wedge) of the material rises above the bed surface is reached then the particles cascade or shower down on the free surface. This motion is associated with the high particle-to-heat transfer fluid exposure.
Case – In heat treating, it is that portion of a ferrous alloy, extending inward from the surface, whose composition has been altered during case hardening. Typically, it is considered to be the portion of an alloy (i) whose composition has been measurably altered from the original composition, (ii) which appears light when etched, or (iii) which has a higher hardness value than the core.
Case crushing – It is a term used for denoting longitudinal gouges arising from fracture in case-hardened gears.
Case hardening – It is a generic term covering several processes applicable to steel which change the chemical composition of the surface layer by absorption of carbon, nitrogen, or a mixture of the two and, by diffusion, create a concentration gradient. The processes normally used are carburizing and quench hardening, cyaniding, nitriding, and carbonitriding.
Casing – It is a covering of sheets of metal or other material such as fire-resistant composition board used to enclose all or a portion of a steam generating unit.
CAS-OB process – It is a ladle treatment process in secondary metallurgy which is used for the heating of steel through chemical means. The abbreviation CAS-OB stands for ‘Composition Adjustment by Sealed Argon Bubbling – Oxygen Blowing’. During the CAS-OB process, the most important functions are the adjustment of the temperature to an optimum level and the accurate addition of alloying elements. The purpose of the heating is to ensure sufficient temperature of the liquid steel when it is sent to the continuous casting machine. The CAS-OB process belongs among the processes which operate at the atmospheric pressure. The CAS-OB process is designed for homogenization and control of the composition and temperature of steel. It is a ladle treatment process which is designed for heating and alloying of liquid steel.
CASS test – CASS test is abbreviation for copper-accelerated salt-spray test.
Castable – In casting, it is a combination of refractory grain and suitable bonding agent which, after the addition of a proper liquid, is normally poured into place to form a refractory shape or structure which becomes rigid because of chemical action.
Castable refractories – These are monolithic refractories which consist of a group of products which with the addition of water, are cast into place. Castable refractories are supplied dry, mixed onsite and installed behind shuttering or cast in a mould to form the required shape.
Castability – It is a complex combination of liquid-metal properties and solidification characteristics which promotes accurate and sound final castings. It is also the relative ease with which a molten metal flows through a mould or casting die.
Cast film – It is a film made by depositing a layer of liquid plastic onto a surface and stabilizing this form by the evaporation of solvent, by fusing after deposition, or by allowing a melt to cool. Cast films are usually made from solutions or dispersions.
Cast house – This is the area around the blast furnace at the tap hole level. It contains equipment for opening and closing of tap-hole and trough and runners for flow of hot metal and liquid slag.
Casting – It is the metal object cast to the required shape by pouring or injecting liquid metal into a mould, as distinct from one shaped by a mechanical process. It is also pouring molten metal into a mould for producing an object of desired shape.
Casting defect – It is an imperfection in a casting which does not satisfy one or more of the needed design or quality specifications. This term is frequently used in a limited sense for those flaws formed by improper casting solidification.
Casting section thickness – It is the wall thickness of the casting. Since the casting cannot have a uniform thickness, the section thickness can be specified at a specific place on the casting. Also, it is sometimes useful to use the average, minimum, or typical wall thickness to describe a casting.
Casting shrinkage – It is the quantity of dimensional change per unit length of the casting as it solidifies in the mould or die and cools to room temperature after removal from the mould or die. There are three distinct types of casting shrinkage. Liquid shrinkage refers to the reduction in volume of liquid metal as it cools to the liquidus temperature. Solidification shrinkage is the reduction in volume of metal from the beginning to the end of solidification. Solid shrinkage involves the reduction in volume of metal from the solidus temperature to room temperature.
Casting strains – These are the strains in a casting caused by casting stresses which develop as the casting cools.
Casting stresses – These are stresses set up in a casting because of geometry and casting shrinkage. These are the residual stresses set up when the shape of a casting impedes contraction of the solidified casting during cooling.
Casting volume – It is the total cubic units (cubic millimeters) of cast metal in the casting.
Casting yield – It is the weight of a casting(s) divided by the total weight of metal poured into the mould, expressed as a percentage.
Cast iron – It is a generic term for a large family of cast ferrous alloys in which the carbon content exceeds the solubility of carbon in austenite at the eutectic temperature. Majority of the cast irons contain at least 2 % carbon, plus silicon and sulphur, and can or cannot contain other alloying elements.
Cast replica – In metallography, it is a reproduction of a surface in plastic made by the evaporation of the solvent from a solution of the plastic or by polymerization of a monomer on the surface.
Cast steel – It is steel in the form of a casting.
Cast structure – It is the metallographic structure of a casting evidenced by shape and orientation of grains and by segregation of impurities.
Catalyst – It is a substance capable of changing the rate of a reaction without itself undergoing any net change. It differs from a curing agent in that the catalyst is not itself chemically consumed in the reaction, while a curing agent is. Technically, catalysts which increase reaction rates are called accelerators, and those which decrease reaction rates are called inhibitors or retarders.
Cataracting motion – The cataracting motion in a rotary kiln is typical with the beginning of a particles throwing away from the bed in the freeboard of the cylinder. With the increase of the rotation speed, the quantity of the ejected particles and the length of their trajectory grow, while a fully covering of the cylinder wall with the treated material is turned out.
Catastrophic failure – It is sudden failure of a component or assembly which frequently results in extensive secondary damage to adjacent components or assemblies.
Catastrophic wear – It is the sudden surface damage, deterioration, or change of shape caused by wear to such an extent that the life of the part is appreciably shortened or action is impaired.
Category – Category is the primary basis for classification using each of the three fundamental criteria of environmental-socio-economic viability (related categories being E1, E2, and E3), technical feasibility (related categories being F1, F2, F3 and F4), and degree of confidence (related categories being G1, G2, G3 and G4) as per UNFC (United Nations Framework Classification for Resources) classification.
Cathode – It is the negative electrode of an electrolytic cell at which reduction is the principal reaction. Electrons flow toward the cathode in the external circuit. Typical cathodic processes are cations taking up electrons and being discharged, oxygen being reduced, and the reduction of an element or group of elements from a higher valence state to a lower valence state. In electro-galvanizing process positive current flows from the anode (zinc) through the electrolyte to the cathode (steel).
Cathode copper – It is the copper deposited at the cathode in electrolytic refining.
Cathode efficiency – It is the current efficiency at the cathode.
Cathode film – It is the portion of solution in immediate contact with the cathode during electrolysis.
Cathode-ray tube (CRT) – A cathode-ray tube is a specialized vacuum tube in which images are produced when an electron beam strikes a phosphorescent surface. It is an electronic tube which permits the visual display of electronic signals.
Cathodic – It is the exhibiting properties of a cathode. Steel is cathodic in relation to zinc.
Cathodic cleaning – It is the electrolytic cleaning in which the work is the cathode.
Cathodic corrosion – It is the corrosion resulting from a cathodic condition of a structure normally caused by the reaction of an amphoteric metal with the alkaline products of electrolysis.
Cathodic disbondment – It is the destruction of adhesion between a coating and its substrate by products of a cathodic reaction.
Cathodic etching – It is done for cleaning of the surfaces of metal samples prior to oxygen determinations. The sample becomes the cathode in a low-pressure argon-ion discharge. The argon ions bombard the surface of the sample and remove the oxide film by an etching process.
Cathodic inhibitor – It is a chemical substance or mixture which prevents or reduces the rate of the cathodic or reduction reaction.
Cathodic pickling – It is the electrolytic pickling in which the work is the cathode.
Cathodic polarization – It is the change of the electrode potential in the active (negative) direction because of the current flow.
Cathodic protection – It is the reduction of corrosion rate by shifting the corrosion potential of the electrode toward a less oxidizing potential by applying an external electromotive force. It is also partial or complete protection of a metal from corrosion by making it a cathode, using either a galvanic or an impressed current. Zinc is higher in the electro-chemical series than iron, and corrodes sacrificially to prevent the corrosion of adjacent exposed steel. Pre-galvanized products (sheet, tube and wire) rely on this feature of the galvanized coating to protect the cut edges of products processed from these sections.
Cathodic reaction – It is the electrode reaction equivalent to a transfer of negative charge from the electronic to the ionic conductor. A cathodic reaction is a reduction process. An example common in corrosion is M(aq)2+ + 2e– M(s).
Cathodoluminescence – It is a radiative transition wherein low-energy light photons are released during electron irradiation.
Catholyte – It is the electrolyte adjacent to the cathode of an electrolytic cell.
Cation – It is a positively charged ion which migrates through the electrolyte toward the cathode under the influence of a potential gradient.
Cation exchange resins (R.H+) – These resins are mainly styrene-divinyl benzene copolymers, which on sulphonation or carboxylation, become capable to exchange their hydrogen ions with the cations in their water. The cations exchange sulphonic acid-formaldehyde resin exchange their H+ ions with the cations present in the water i.e., Ca2+ and Mg2+.
Cationic detergent – It is a detergent which produces aggregates of positively charged ions with colloidal properties.
Caul – In adhesive bonding, it is a sheet of material used singly or in pairs in the hot or cold pressing of assemblies being bonded. A caul is used to protect either the faces of the assembly or the press platens, or both, against marring and staining in order to prevent sticking, facilitate press loading, impart a desired surface texture or finish, and provide uniform pressure distribution. A caul can be made of any suitable material such as aluminum, stainless steel, hardboard, fiberboard, or plastic, the length and width dimensions normally being the same as those of the plates of the press where it is used.
Caulk weld -It is a nonstandard term for seal weld which is a weld designed mainly to provide a specific degree of tightness against leakage.
Cause and effect analysis diagrams – These are casual diagrams which show the causes of a specific event. Common uses of these diagrams are (i) product design and quality defect prevention, and (ii) to identify potential factors causing an overall effect. Each cause or reason for imperfection is a source of variation.
Caustic – It means burning or corrosive. It is also a hydroxide of a light metal, such as sodium hydroxide or potassium hydroxide.
Caustic cracking – It is a form of stress-corrosion cracking very frequently encountered in carbon steels or iron-chromium-nickel alloys which are exposed to concentrated hydroxide solutions at temperatures of 200 deg C to 250 deg C. It is also known as caustic embrittlement.
Caustic degreasing – All steel products are degreased in a hot caustic solution as the first stage of the pretreatment process for galvanizing. The acid pickling is not effective unless all organic contamination, grease, and oil are removed from the steel’s surface. In the hot dip galvanizing process, organic residues are removed by immersing steel in a tank of caustic solution.
Caustic dip – It is a strongly alkaline solution into which metal is immersed for etching, for neutralizing acid, or for removing organic materials such as greases or paints.
Caustic embrittlement – It is an obsolete historical term denoting a form of stress-corrosion cracking most frequently encountered in carbon steels or iron-chromium-nickel alloys which are exposed to concentrated hydroxide solutions at temperatures of 200 deg to 250 deg C. In boilers, it is the phenomenon during which the boiler material becomes brittle because of the accumulation of caustic substances. This type of boiler corrosion is caused by the use of highly alkaline water in the high-pressure boiler.
Caustic quenching – It is the quenching with aqueous solutions of 5 % to 10 % sodium hydroxide (NaOH).
Cavitation – It is the formation and collapse, within a liquid, of cavities or bubbles which contain vapour or gas or both. In general, cavitation originates from a decrease in the static pressure in the liquid. It is distinguished in this way from boiling, which originates from an increase in the liquid temperature. There are certain situations where it can be difficult to make a clear distinction between cavitation and boiling, and the more general definition which is given here is hence to be preferred. In order to erode a solid surface by cavitation, it is necessary for the cavitation bubbles to collapse on or close to that surface.
Cavitation corrosion – It is a process involving conjoint corrosion and cavitation.
Cavitation damage – It is the degradation of a solid body resulting from its exposure to cavitation. This can include loss of material, surface deformation, or changes in properties or appearance.
Cavitation erosion – It is the progressive loss of original material from a solid surface because of continuing exposure to cavitation.
Cavity – It is the mould impression or die impression which gives a casting its external shape.
CCT diagram – It is the continuous cooling transformation diagram. It is the set of curves drawn using logarithmic time and linear temperature as coordinates, which define, for each cooling curve of an alloy, the beginning and end of the transformation of the initial phase.
Cell – In electrochemistry, It is the electrochemical system consisting of an anode and a cathode immersed in an electrolyte. The anode and cathode can be separate metals or dissimilar areas on the same metal. The cell includes the external circuit, which permits the flow of electrons from the anode toward the cathode.
Cellulose coating – This type of electrode coting provides a gaseous shield with a reducing agent in which the gas shield surrounding the arc is produced by the disintegration of cellulose.
Cement – Any substance which bonds materials is normally considered as cement. There are several types of cements. In construction, the term cement normally refers to bonding agents which are mixed with water or other liquid, or both, to produce a cementing paste.
Cementation – It is the introduction of one or more elements into the outer portion of a metal object by means of diffusion at high temperature.
Cement copper – It is the impure copper recovered by chemical deposition when iron (very frequently shredded steel scrap) is brought into prolonged contact with a dilute copper sulphate solution.
Cemented carbide – It is a solid and coherent mass made by pressing and sintering a mixture of powders of one or more metallic carbides, such as tungsten carbide, and a much smaller quantity of a metal, such as cobalt, to serve as a binder.
Cementite – It is a hard (800 Vickers hardness, HV), brittle compound of iron and carbon, known chemically as iron carbide and having the approximate chemical formula Fe3C. It is characterized by an orthorhombic crystal structure. When it occurs as a phase in steel, the chemical composition is to be altered by the presence of manganese and other carbide-forming elements. The highest cementite contents are observed in white cast irons, which are used in applications where high wear resistance is needed.
Central computer system (CCS) -It is the top level of the control system and has databases of the whole plant, which is obtained by collecting and stocking information of the subordinate computers. It uses the databases in the elaboration of the planning of material purchasing and production, as well as in the production report and technical analysis of the production data.
Central processing unit (CPU) – It is also called a central processor, main processor, or just processor. It is the most important processor in a computer. Its electronic circuitry executes instructions of a computer program, such as arithmetic, logic, controlling, and input / output (I/O) operations. Principal components of a CPU include the arithmetic–logic unit (ALU) which performs arithmetic and logic operations, processor registers which supply operands to the ALU and store the results of ALU operations, and a control unit that orchestrates the fetching (from memory), decoding and execution (of instructions) by directing the coordinated operations of the ALU, registers, and other components. Majority of the modern CPUs are implemented on integrated circuit (IC) microprocessors, with one or more CPUs on a single IC chip. Microprocessor chips with multiple CPUs are called multi-core processors.
Central tendency of data – In statistics this is described by the central limit theorem. This theorem states the fact that if one draws samples of size ‘n’ from the population and calculates the mean of these samples, the means forms a distribution which tends toward normality regardless of the form of the original sample distribution.
Centre – It is the difference in thickness between the middle and edges (average) of a sheet.
Centre buckle – It is bulging of a large, flat face of a casting. In investment casting, it is caused by dip coat peeling from the pattern. It is an indentation in a casting, resulting from expansion of the sand, and can be termed the start of an expansion defect. It is also a local waviness in metal bar or sheet, normally transverse to the direction of rolling.
Centre drilling – It consists of drilling a short, conical hole in the end of a work-piece. It is a hole to be used to centre the work-piece for turning on a lathe.
Centre-less grinding – It consist of grinding the outside or inside diameter of a cylindrical piece which is supported on a work support blade instead of being held between centres and which is rotated by a so-called regulating or feed wheel.
Centre-line shrinkage – It is the porosity because of the incomplete fill after partial solidification of a casting (ingots or continuous-cast slabs or billets) or which occurs along the central plane or axis of a cast metal section.
Centrifugally cast rolls – The composition of centrifugally cast rolls is more or less similar to that of double poured rolls. First, metal which gives high hardness and better wearing properties is poured in the mould, which is then revolved at high speed. After sometime, molten metal of different composition is poured in for the core of the roll to make the core tougher. These rolls are superior to double poured rolls as the shell portion is denser giving better properties. The centrifugally cast rolls are also known as duplex rolls.
Centrifugal casting – It is the process of filling moulds by (i) pouring metal into a sand or permanent mould which is revolving about either its horizontal or its vertical axis, or (ii) pouring metal into a mould which is subsequently revolved before solidification of the metal is complete. Horizontal centrifugal casting is used to produce rotationally symmetric parts, such as pipes, tubes, bushings, and other parts. Vertical centrifugal casting can be used to produce both symmetrical as well as non-symmetrical parts. However, since only a reasonable quantity of imbalance can be tolerated for a non-symmetrical part, the most common shapes produced are cylinders and rotationally symmetric flanged parts. Centrifugal casting of metal produces a finer grain structure and thinner ribs and webs than can be achieved in ordinary static mould casting.
Centrifugal classifier – It utilizes centrifugal forces in a similar way to cyclones to induce fine particle separation. The classifier is capable of separations in the range of 100 micrometers to 15 micrometers. The classifier has widespread acceptance in industrial minerals, cement and fly ash applications. It has high degree of separation accuracy and exceptionally low maintenance requirements. The classifier is used in conjunction with a dust collector and system fan.
Centrifugal discharge elevators – In this elevator, the buckets are spaced at a regular pitch to avoid interference in loading and discharging. The charging of buckets is by scooping action and the discharge is by centrifugal action. These elevators are normally used in vertical configuration and used for practically all types of free flowing, small lump materials like grain, coal, sand, clay, sugar, dry chemicals etc. Both belt and chain can be used and the speed of these elevators range between 1.1 metres per minute to 2 metres per minute.
Centrifugal fans – These fans increase the speed of an air / gas stream with a rotating impeller. The speed increases as the air / gas reaches the ends of the blades and is then converted to pressure. These fans are capable of generating high pressures, which makes them suitable for harsh operating conditions, such as systems with high temperatures, dirty air / gas streams (high moisture and particulate content), and material handling. The centrifugal design uses the centrifugal force generated by a rotating disk, with blades mounted at right angles to the disk, to impart movement to the air or gas and increase its pressure. The assembly of the hub, disk, and blades is known as the fan wheel, and frequently includes other components with aerodynamic or structural functions.
Centrifugal pumps – These pumps operate by applying a centrifugal force to fluids. These pumps use the centrifugal force imparted to the fluid by one or more rotating elements (impellers) to increase the kinetic and pressure energy of the fluid. These pumps produce a head and a flow by increasing the velocity of the liquid through the machine with the help of a rotating vane impeller. Centrifugal pumps comprise radial, semi-axial and axial pumps, but also side channel, peripheral and liquid-ring pumps whose working principles are fundamentally different from that of the first group.
Centrifuge casting – It is a casting technique in which mould cavities are spaced symmetrically about a vertical axial common down-gate. The entire assembly is rotated about that axis during pouring and solidification.
Centrifuge work – It is the process of removing excess zinc from small hot dip galvanized parts by placing them in a perforated, rapidly spinning cylindrical container. Small parts which cannot be efficiently handled individually are centrifuged or spun to remove excess zinc and allow them to be processed in bulk in baskets. Nails, washers, bolts, and chains are typical centrifuge products.
Centrifuging bed motion – It occurs at critical and high speeds of rotation in a rotary kiln. This is an extreme condition in which all the bed material rotates with the drum wall.
Ceramic – Ceramics are a class of inorganic, non-metallic products which are subject to a high temperature during manufacture or use. Typically, but not exclusively, a ceramic is a metallic oxide, boride, carbide, or a mixture or compound of such materials, i.e., ceramics include anions which play important roles in atomic structures and properties. A ceramic is any of the various hard, brittle, heat-resistant, and corrosion-resistant materials made by shaping and then firing an inorganic, nonmetallic material, such as fireclay, at a high temperature. Refractories are ceramic materials.
Ceramic coatings – These coatings include glasses, with or without additions of refractory compounds; high-temperature coatings based on oxides, carbides, silicides, borides, or nitrides, cermets, and other inorganic materials. Ceramic coatings are applied to metals to protect them against oxidation and corrosion at room temperature and at high temperatures. Special coatings have been developed for specific uses, including wear resistance, chemical resistance, high reflectivity, electrical resistance, and prevention of hydrogen diffusion. Ceramic-coated metals are used for furnace components, heat treating equipment, chemical processing equipment, heat exchangers, rocket motor nozzles, exhaust manifolds, jet engine parts, and nuclear power plant components.
Ceramic-metal coating – It is a mixture of one or more ceramic materials in combination with a metallic phase applied to a metallic substrate which van or cannot need heat treatment prior to service. This term can also be used for coatings applied to non-metallic substrates, for example, graphite.
Ceramic mould casting – Ceramic mould casting techniques are based on proprietary processes which use permanent patterns and fine-grain zircon (ZrSiO4) and calcined, high-alumina (Al2O3) mullite slurries for moulding. Except for distribution of grain size, the zircon slurries are comparable in composition to those used in ceramic shell investment moulding.
Ceramic moulding – It is a precision casting process which uses permanent patterns and fine-grain slurry for making moulds. Unlike monolithic investment moulds, which are similar in composition, ceramic moulds consist of a cope and a drag or, if the casting shape permits, a drag only.
Ceramic process – It is the production of articles or coatings from essentially inorganic, non-metallic materials, the article or coating being made permanent and suitable for utilitarian and decorative purposes by the action of heat at temperatures sufficient to cause sintering, solid-state reactions, bonding, or conversion partially or wholly to the glassy state.
Ceramic tools – These are cutting tools made from sintered, hot-pressed, or hot isostatically pressed alumina-base or silicon nitride-base ceramic materials.
Ceramic welding – Ceramic welding is a method of repairing coke oven refractories. It is the welding of silica brick inside the coke oven. This is accomplished by conveying a powder mixture, rich in silica, through a small pipe lance via an oxygen enriched compressed air stream. The powdered silica mixture is jetted out of the end of the lance and ignites, almost explodes, against the hot wall of the coke oven. The heat of the reaction penetrates the silica brick creating a plastic zone of silica. The reaction also turns the powder silica mixture into a molten mass, which bonds to the aforementioned plastic zone on the silica brick. The appearance is similar to that of a welding joint. Also, the effects are similar, as new, equally strong material is deposited onto existing worn and cracked silica brick.
Cerium – It is a rare earth metal which in many respects resembles the alkali metals. The hot working properties of high alloy corrosion resistant and heat-resistant steels can be improved by the addition of cerium. Cerium in cast iron, acts as a deoxidizer and desulphurizer but when the sulphur content has been reduced to a value of around 0·015 %, cerium enters into solution in the cast iron and functions as a powerful carbide stabilizer. In quantities above 0·02 %, cerium is the operative factor in the production of nodular graphite structures in cast iron. Cerium is used in the improving the steel cleanliness, modifying the morphology of inclusions, and micro-alloying of steels. Cerium when added in small amounts to certain heat-resistant steels increases the resistance to oxidation and high temperature corrosion.
Cermet – Cermet is an acronym to designate ‘a heterogeneous combination of metal(s) or alloy(s) with one or more ceramic phases in which the latter constitutes approximately 15 % to 85 % by volume and in which there is relatively little solubility between metallic and ceramic phases at the preparation temperature’. It is a powder metallurgy product consisting of ceramic particles bonded with a metal.
C-frame press – It is also known as gap-frame press which is a general classification of press in which the uprights or housings are made in the form of a letter C, hence making three sides of the die space accessible.
CG iron – It is the compacted graphite cast iron which is the cast iron having a graphite shape intermediate between the flake form typical of gray cast iron and the spherical form of fully spherulitic ductile cast iron.
Chafing – It is the repeated rubbing between two solid bodies which can result in surface damage and / or wear.
Chafing fatigue – It is the fatigue initiated in a surface damaged by rubbing against another body.
Chain – A chain is a series of connected links which are typically made of metal. A chain can consist of two or more links. Chains can be classified in several different ways. From a theoretical viewpoint, a chain is a continuous flexible rack engaging the teeth on a pair of gears. From a viewpoint based on its history and development, chain is a mechanical belt running over sprockets which can be used to transmit power or convey materials. Chains have the four basic functions namely (i) to transmit power, (ii) to convey objects or materials, (iii) to convert rotary motion to linear motion, or linear motion to rotary motion, and (iv) to synchronize or to time motion.
Chain and sprocket drive – The chain and sprocket arrangement operate similar to a bicycle. There is a large sprocket wrapping around the rotary drum with a chain on it which goes to the reducer and motor. The spinning motor turns a gear box, which spins a small sprocket which is attached by the chain to the large sprocket wrapping around the rotary drum. Chain and sprocket drive set ups are reserved for small rotary kilns, running up to 55 kilowatts power. This type of arrangement is not suitable for larger kilns running above 55 kilowatts power.
Chain conveyors – The term chain conveyor means a group of different types of conveyors used in diverse applications, characterized by one or multiple strands of endless chains which travel entire conveyor path, driven by one or a set of sprockets at one end and supported by one or a set of sprockets on the other end. Materials to be conveyed are carried directly on the links of the chain or on specially designed elements attached to the chain. The load carrying chain is normally supported on the idle sprockets or the guide ways. The endless chains are kept tight by suitable chain tensioning device at the non-driven end.
Chain driven belt conveyor – It is a special type of conveyor in which the specially designed belt is driven by a moving chain, where belt only serves as load carrier, and motion is by a chain conveyor.
Chain intermittent weld – It is an intermittent weld on both sides of a joint in which the weld increments on one side are approximately opposite those on the other side.
Chain reaction – It is a reaction which initiates its own repetition. In a fission chain reaction, for example, neutrons released in fission produce an additional fission in at least one further nucleus. These, in turn, can be absorbed by other fissionable nuclei, releasing still more neutrons. Where the number of neutrons released in a given time equals or exceeds the number of neutrons lost by absorption the fission chain reaction is self-sustaining.
Chain slings – These slings are made from steel chains. Chains are normally used because of their strength and ability to adapt to the shape of the load. However, care is required to be taken, while using alloy steel chain slings since these slings are subject to damage by sudden shocks. Misuse of steel chain slings can damage the sling, resulting in sling failure and possible accident.
Chain work – Large or complex steel fabrications which need to be handled individually are suspended on chains for galvanizing. These products include large pipes, box and boat trailers, and heavy items.
Chalcopyrite – It is a sulphide mineral of copper and iron. It is the most important ore mineral of copper.
Chalking – It is the development of loose removable powder at the surface of an organic coating normally caused by weathering.
Chamfer – It is a beveled surface to eliminate an otherwise sharp corner. It is also a relieved angular cutting edge at a tooth corner.
Chamfer angle – It is the angle between a reference surface and the bevel. On a milling contour, it is the angle between a beveled surface and the axis of the cutter.
Chamfering – It is the making of a sloping surface on the edge of a member. It is also called beveling.
Channel induction furnace – It consists of a refractory lined steel shell which contains the molten metal. Attached to the steel shell and connected by a throat is an induction unit which forms the melting component of the furnace. The induction unit consists of an iron core in the form of a ring around which a primary induction coil is wound. This assembly forms a simple transformer in which the molten metal loops comprise the secondary component. The heat generated within the loop causes the metal to circulate into the main well of the furnace. The circulation of the molten metal causes a useful stirring action in the melt. The channel IF is normally used for melting low melting point alloys, or as a holding and superheating unit for higher melting point alloys such as cast iron.
Channeling – The phenomenon of channeling happens when the ascending gases in the furnace does not properly get uniformly distributed both radially and circumferentially in the furnace and find a passage of least resistance.
Channeling pattern – It is a pattern of lines observed in a scanning electron image of a single-crystal surface caused by preferential penetration, or channeling, of the incident beam between rows of atoms at certain orientations. The pattern provides information on the structure and orientation of the crystal.
Channels – Channels are C-shaped hot-rolled carbon steel sections featuring a vertical web and rounded corners on the top and bottom flanges. They include a wide web and two flanges, which can be either parallel or tapered.
Chaplet – It is the metal support which holds a core in place within a casting mould. Molten metal solidifies around a chaplet and fuses it into the finished casting.
Characteristic electron energy loss phenomena – It consists of the inelastic scattering of electrons in solids that produces a discrete energy loss determined by the characteristics of the material. The most probable form is because of the excitation of valence electrons.
Characteristic radiation – It consists of electro-magnetic radiation of a particular set of wave-lengths, produced by and characteristic of a particular element whenever its excitation potential is exceeded. Electro-magnetic radiation is emitted as a result of electron transitions between the different energy levels (electron shells) of atoms. The spectrum consists of lines whose wavelengths depend only on the element concerned and the energy levels involved.
Characterization – It is the process of classifying nuclear material.
Charge – It is the materials fed into a furnace. It is the weights of different liquid and solid materials put into a furnace during one feeding cycle.
Charge conveyor – It is the conveyor with steel cord rubber belt for taking charge materials to the furnace top from the stock house. Conveyor charging is alternate to skip charging.
Charge coupled device – It is a highly sensitive photon detector. It is divided up into a large number of light-sensitive small areas known as pixels, which can be used to assemble an image of the area of interest. A charge coupled device is a silicon-based multi-channel array detector of ultra-violet, visible and near-infra light.
Charging – For a lap, it is impregnating the surface with fine abrasive. It is also placing materials into a furnace.
Charging equipment – It is the equipment used for charging of materials at the top of the blast furnace without allowing escape of blast furnace gas to the atmosphere.
Charpy test – It is an impact test in which a V-notched, keyhole-notched, or U-notched sample, supported at both ends, is struck behind the notch by a striker mounted at the lower end of a bar which can swing as a pendulum. The energy which is absorbed in fracture is calculated from the height to which the striker would have risen had there been no sample and the height to which it actually rises after fracture of the sample.
Chase (machining) – It is to make a series of cuts each, except for the first, following in the path of the cut preceding it, as in chasing a thread.
Chatter – In machining or grinding, (i) it is a vibration of the tool, wheel, or work-piece producing a wavy surface on the work, and (ii) the finish produced by such vibration. tribology, it is the elastic vibrations resulting from frictional or other instability.
Chatter marks – These are surface imperfections on the work being ground, normally caused by vibrations transferred from the wheel-work interface during grinding.
Check – It is the intermediate section of a flask which is used between the cope and the drag when moulding a shape that requires more than one parting plane. It is also a crack in a die impression corner, normally because of the forging strains or pressure, localized at some relatively sharp corner. Die too hard for the depth of the die impression have a tendency to check or develop cracks in impression corners. Check is also one of a series of small cracks resulting from thermal fatigue of hot forging dies.
Checked edges – These are sawtooth edges seen after hot rolling and / or cold rolling.
Checker refractories – A checker Brick is a kind of heat carrier with features of good volume stability, excellent high temperature load creep property, high density and low apparent porosity for such applications as in hot blast stove of blast furnace and flame furnace.
Checkers – In a chamber associated with a metallurgical furnace, it is the bricks stacked openly so that heat can be absorbed from the combustion products and later transferred to incoming air when the direction of flow is reversed.
Checking – It is the development of slight breaks in a coating which do not penetrate to the underlying surface.
Checks – These are several, very fine cracks in a coating or at the surface of a metal part. Checks can appear during processing or during service and are most frequently associated with thermal treatment or thermal cycling. It is also called check marks, or heat checks. Checks are also minute cracks in the surface of a casting caused by unequal expansion or contraction during cooling. Checks are also cracks in a die impression corner, normally because of the forging strains or pressure, localized at some relatively sharp corner. Die blocks too hard for the depth of the die impression have a tendency to check or develop cracks in impression corners. Checks are also a series of small cracks resulting from thermal fatigue of hot forging dies.
Check sheets – These are simple data gathering devices. They are used to collect data effectively and efficiently. They prepare data for further analysis. A check sheet is in the form of a designed format used to collect data in a systematic manner and in real time at the location where the data is generated. The data it captures can be either quantitative or qualitative. When the information is quantitative, the check sheet is sometimes called a tally sheet. The defining characteristic of a check sheet is that data are recorded by making marks (checks) on it.
Check valve – It is a one-directional valve which is opened by the fluid flow in one direction and which closes automatically when the flow stops or reverses direction.
Chelate – It is a coordination compound in which a heterocyclic ring is formed by a metal bound to two atoms of the associated ligand.
Chelating agent – It is an organic compound in which atoms form more than one coordinate bond with metals in solution. It is also a substance used in metal finishing for controlling or eliminating certain metallic ions present in undesirable quantities.
Chelation – It is a chemical process involving formation of a heterocyclic ring compound which contains at least one metal cation or hydrogen ion in the ring.
Chemical absorption process – It involves one or more reversible chemical reactions between carbon di-oxide and an aqueous solution of an absorbent, such as mono-ethanol-amine based solvent, and high-performance amines (activated methyl diethanolamine) etc. Upon heating the product, the bond between the absorbent and carbon di-oxide can be broken, yielding a stream enriched in carbon di-oxide. The chemical absorption process for separating carbon di-oxide from flue gas is borrowed from the gas processing industry. Amine based processes are being used commercially for the removal of acid gas impurities (carbon di-oxide and hydrogen sulphide) from process gas streams.
Chemical adsorption– It is same as chemisorption which is the binding of an adsorbate to the surface of a solid by forces whose energy levels approximate those of a chemical bond.
Chemical analysis – It is the determination of the principal chemical constituents.
Chemical bonding – It is the joining together of atoms to form molecules.
Chemical cleaning – It is the process of immersing steel in chemical solvents to remove (dissolve) residues which otherwise prevents the galvanized coating from forming.
Chemical conversion coating – It is a protective or decorative non-metallic coating produced in situ by chemical reaction of a metal with a chosen environment. It is frequently used to prepare the surface prior to the application of an organic coating.
Chemical deposition – It is the precipitation or plating-out of a metal from solutions of its salts through the introduction of another metal or reagent to the solution.
Chemical equation – It is a symbolic representation of a chemical reaction in the form of symbols and formulas, where the reactant entities are given on the left-hand side and the product entities on the right-hand side.
Chemical etching – It is the dissolution of the material of a surface by subjecting it to the corrosive action of an acid or an alkali.
Chemical feed pipe – It is a pipe inside a boiler drum through which chemicals for treating the boiler water are introduced.
Chemical film binder – A chemical film binder coats the particles of a material with a thin film and causes a brief chemical reaction which bonds the particles together. when a chemical film binder is used, the resulting briquette is frequently water-proof. Examples of chemical film binders are sodium silicate and dilute acid, or sodium silicate and lime.
Chemical flux cutting – It is an oxygen-cutting process in which metals are severed using a chemical flux to facilitate cutting.
Chemically precipitated powder – It is a metal powder which is produced as a fine precipitate by chemical displacement.
Chemical machining – It consists of removing the metal stock by controlled selective chemical dissolution.
Chemical matrix binders – A chemical matrix binder uses a chemical reaction between two binder components for binding the material particles together. Examples of chemical matrix binders are quick lime (CaO) and water, molasses and slaked lime, and water and plaster of Paris.
Chemical metallurgy – It is the science and technology of winning metals from their ores and purifying metals. Its two chief branches are extractive metallurgy and refining.
Chemical milling – It is the machining process in which metal is formed into intricate shapes by masking certain portions and then etching away the unwanted material.
Chemical polishing – It is a process which produces a polished surface by the action of a chemical etching solution. The etching solution is compounded so that peaks in the topography of the surface are dissolved preferentially.
Chemical potential – In a thermodynamic system of several constituents, it is the rate of change of the Gibbs function of the system with respect to the change in the number of moles of a particular constituent.
Chemical reaction – It is a process which leads to the chemical transformation of one set of chemical substances to another. When chemical reactions occur, the atoms are rearranged and the reaction is accompanied by an energy change as new products are generated.
Chemical reaction binders – A chemical reaction binder uses a chemical reaction to form a strong bond between the material particles to be briquetted and the binder. Examples of the chemical reaction are electric arc furnace dust mix with a water and quick lime binder, and power plant fly ash (which contains lime) mixed with water. A reagent such as dilute sulphuric acid or phosphoric acid is sometimes added to cure the strength of the briquette.
Chemical stress – It is the stress in the material because of chemical attack. In refractories, the property related to chemical stress is important for having resistance against chemical attack by slags, liquid materials, gases, and flue dust which the refractories come in contact during service. The important refractory properties for meeting the chemical stresses are chemical composition, mineralogical composition and crystal formation, pore size distribution and types of pores, gas permeability and resistance to slag, glass melts, gases and vapours.
Chemical vapour deposition (CVD) – The chemical vapour deposition process can be defined as the deposition of a solid on a heated surface through a chemical reaction from the vapour or gas phase. It belongs to the class of vapour-transport processes which are atomistic in nature, i.e., the deposition species are atoms or molecules, or a combination thereof. This process is a coating process, similar to gas carburizing and carbonitriding, whereby a reactant atmosphere gas is fed into a processing chamber where it decomposes at the surface of the work-piece, liberating one material for either absorption by, or accumulation on, the work-piece. A second material is liberated in gas form and is removed from the processing chamber, along with excess atmosphere gas.
Chemical wear – It is the corrosive wear. It is the wear in which chemical or electro-chemical reaction with the environment is significant.
Chemisorption – It consists of the binding of an adsorbate to the surface of a solid by forces whose energy levels approximate those of a chemical bond.
Chevron conveyor belt – This belt is are highly effective for transporting sand, coal powder, grain, or other powder or granular materials or materials packed in bags or boxes on incline though they can transport coal or mineral ore just like ordinary conveyor belts. They can transport powder or granular materials on 17 degrees to around 28 degrees inclines and materials packed in bags or boxes on 30 degrees to around 35 degrees inclines.
Chevron method – In the chevron method, the material is deposited by the stacker moving to and fro over the centre line of the pile. The chevron stacking method causes segregation of the material with fine particles in the central part of the pile and coarse particles on the surface and at the bottom of the pile. For ensuring proper blending, a chevron pile is hence to be reclaimed from the face of the pile, working across the entire cross section.
Chevron pattern – It is a fractographic pattern of radial marks (shear ledges) which look like nested letters ‘V’. Sometimes it is called a herringbone pattern. Chevron patterns are typically found on brittle fracture surfaces in parts whose widths are considerably higher than their thicknesses. The points of the chevrons can be traced back to the fracture origin.
Chill – It is a metal or graphite insert embedded in the surface of a casting sand mould or core or placed in a mould cavity for increasing the cooling rate at that point. It is also white iron occurring on a gray or ductile iron casting, such as the chill in the wedge test.
Chill coating – It consists of applying a coating to a chill which forms part of the mould cavity so that the metal does not adhere to it, or applying a special coating to the sand surface of the mould which causes the iron to undercool.
Chilled iron – It is the cast iron which is poured into a metal mould or against a mould insert so as to cause the rapid solidification which frequently tends to produce a white iron structure in the casting.
Chilling – The chilling of a blast furnace hearth occurs when the temperature of the hot metal which is tapped from the furnace is very low. The chilling of a blast furnace is a very serious phenomenon which happens due to the abnormal operation of the blast furnace. The revival of a chilled blast furnace is a big and herculean task and it takes a very long time and needs a lot of patience to bring back a chilled blast furnace to normal working condition
Chill ring – It is a non-standard term for backing ring which is the backing in the form of a ring, normally used in the welding of pipe.
Chimney valve – It is intended to separate the blast furnace stove from the chimney. In the plenum chamber of the stove below the grid which supports the checkers are openings to the chimney and to the cold blast main.
Chinese-script eutectic – It is a configuration of eutectic constituents, found particularly in some cast alloys of aluminum containing iron and silicon and in magnesium alloys containing silicon, which resembles the characters in Chinese script.
Chip breaker – It is a notch or groove in the face of a tool parallel to the cutting edge, designed to break the continuity of the chip. It is also a step formed by an adjustable component clamped to the face of the cutting tool.
Chip mark – It is the repeating depression caused by a particle adhering to a rotating roll over which the metal has passed.
Chipping – It is removing seams and other surface imperfections in metals manually with a chisel or gouge, or by a continuous machine, before further processing. Similarly, it is also removing excessive metal.
Chips – These are pieces of material removed from a work-piece by cutting tools or by an abrasive medium.
Chlorinated lubricant – It is a lubricant containing a chlorine compound which reacts with a rubbing surface at high temperatures to protect it from sliding damage.
Chlorinated solvent – It is a liquid organic compound of carbon, hydrogen, and chlorine such as methylene chloride, perchloroethylene, 1,1,1-trichloroethane, and trichloroethylene. These solvents are very effective for degreasing with a minimum fire hazard, but their use is heavily regulated because of their classification as ozone-depleting chemicals.
Chlorination – It is roasting ore in contact with chlorine or a chloride salt for producing e chlorides. It is also removing dissolved gases and entrapped oxides by passing chlorine gas through molten metal such as aluminum and magnesium.
Chlorine – It is a halogen element which is isolated as a heavy greenish-yellow diatomic gas of pungent odour. It is used as a bleach, strong oxidizing agent, and disinfectant in water purification. It is an extremely reactive element and has the highest electron affinity.
Chlorine extraction – It is the removal of phases by formation of a volatile chloride.
Choke – It is an inductor used to block higher-frequency alternating currents while passing direct current and lower-frequency alternating currents in a circuit. A choke normally consists of a coil of insulated wire often wound on a magnetic core, although some consist of a doughnut-shaped ferrite bead strung on a wire. The choke’s impedance increases with frequency.
Choke valve – It is a type of flow control valve which is used for regulating the flow of fluids, such as gases or liquids, in a pipeline.
Chop – It is the metal sheared from a vertical surface of a die forging, which is spread by the die over an adjoining horizontal surface
Chord modulus – It is the slope of the chord drawn between any two specific points on a stress-strain curve. It is a term normally used in the polymer field to specify how a single value for the modulus of elasticity is determined from a non-linear load elongation graph from a tensile test.
C-hook – It is a device which enables the lifting of a coil through the insertion of the hook into the coil’s inner diameter. A motorized hook rotator powers the rotation of the hook attached to the bottom block of a hoist for additional load control.
Chord modulus – It is the slope of the chord drawn between any two specific points on a stress-strain curve.
Chromadizing – It is improving paint adhesion on aluminum or aluminum alloys, mainly aircraft skins, by treatment with a solution of chromic acid. It is also called chromidizing or chromatizing. It is not to be confused with chromating or chromizing.
Chromate quenching – It is treating metal in a tank of containing a solution of chromium compounds to produce a conversion coating consisting of trivalent and hexavalent chromium compounds. After galvanizing, the steel item is cooled by quenching in a water bath containing a low concentration of sodium dichromate. The sodium dichromate solution creates a passivation film on the galvanized surface. Chromate passivation sometimes is used on galvanized reinforcement bars to control reactions between zinc and concrete while the concrete cures, particularly the hydrogen evolution which adversely affects bonding. Chromate quenching of galvanized articles prevents the formation of wet storage stain.
Chromate treatment – It is a treatment of metal in a solution of a hexavalent chromium compound to produce a conversion coating consisting of trivalent and hexavalent chromium compounds.
Chromatic aberration – It is a defect in a lens or lens system which results in different focal lengths of the lens for radiation of diverse wavelengths. The dispersive power of a simple positive lens focuses light from the blue end of the spectrum at a shorter distance than light from the red end. An image produced by such a lens shows colour fringes around the border of the image. The difference in the position along the axis for the focal points of light is called longitudinal chromatic aberration. The difference in the magnification because of the variations in position of the principal points for light of different wave-lengths, also a difference in focal length, is known as lateral chromatic aberration.
Chromating – It is performing of a chromate treatment. It is also the chromate quenching of a galvanized article.
Chromatogram – It is the visual display of the progress of a separation achieved by chromatography. A chromatogram shows the response of a chromatographic detector as a function of time.
Chromatography – It is a separation method based on the distribution of sample compounds between the stationary phase and a mobile phase.
Chrome-magnesite refractories – These refractories normally contain 15 % to 35 % Cr2O3 and 42 % to 50 % MgO. They are produced from sintered magnesia and chrome ore.
Chrome pickle – It consists of producing a chromate conversion coating on magnesium for temporary protection or for a paint base. It is also the solution which produces the conversion coating.
Chromite – It is the main ore mineral of chromium.
Chromium – Chromium is a chemical element. It is a steely-grey, lustrous, hard, and brittle transition metal. It is valued for its high corrosion resistance and hardness. Chromium is normally added to steel to increase corrosion resistance, wear resistance, and oxidation resistance, to increase hardenability, or to improve high temperature strength.
Chromium buffing compound – It is a buffing compound consisting of fine unfused alumina. Originally, it has been developed to colour buff chromium-plated parts which had been stained or frosted in the electroplating process.
Chromium-molybdenum steels – These steels are heat resistant steels. They contain 0.5 % chromium to 9 % chromium and 0.5 % molybdenum to 1 % molybdenum. The carbon content is normally below 0.2 %. Chromium provides improved oxidation and corrosion resistance while the molybdenum increases strength at high temperatures. These steels are normally produced in the normalized and tempered, quenched and tempered or annealed conditions. These steels are extensively used in the oil and gas industries and in fossil fuel and nuclear power plants.
Chromium plating – It is the electro-deposition of chromium on a substrate.
Chromizing – It is a surface treatment at high temperature, normally carried out in pack, vapour, or salt baths, in which an alloy is formed by the inward diffusion of chromium into the base metal.
Chronic problem – It is a problem because of the inherent variation in a process being more than permitted by the specifications.
Chuck – It is a device for holding work or tools on a machine so that the part can be held or rotated during machining or grinding.
Chucking lug – It is a lug or boss added to a forging so that on-centre machining and forming can be performed with one setup or checking. This lug is finally machined or cut away.
Chute – It an opening, normally constructed of steel and equipped with a gate, through which material is drawn from a storage bin. It is also a part of the bell less charging equipment for charging charge material in the blast furnace. The chute is normally rotated while charging and its angle to the vertical can be changed.
Cinching – Cinching is scratch which is for rolled products, it is a sharp indentation in the surface normally caused by a machine or during handling, while for extrusions, it is a synonym for handling mark.
Cinder notch – It is also known as slag notch. All the blast furnaces do not have this notch. The cinder notch is used for tapping of slag from the furnace.
Cinnabar – It is a vermilion-coloured ore mineral of mercury.
CIP – It is the acronym for cold isostatic pressing, which is a forming technique in which high fluid pressure is applied to a powder (metal or ceramic) part at ambient temperature. Water or oil is used as the pressure medium.
Circle – It is a circular blank fabricated from plate, sheet, or foil.
Circle grid – It is a regular pattern of circles, frequently 2.5 mm in diameter, marked on a sheet metal blank.
Circle-grid analysis – It is the analysis of deformed circles for determining the severity with which a sheet metal blank has been deformed.
Circle grinding – It is either cylindrical grinding or internal grinding which are the preferred terms.
Circle shear – It is a shearing machine with two rotary disk cutters mounted on parallel shafts driven in unison and equipped with an attachment for cutting circles where the desired piece of material is inside the circle. It cannot be used to cut circles where the desired material is outside the circle.
Circofer process – The Circofer process is similar to the Circored process. It reduces fine ores with coal in a circulating fluidized bed, in which the reducing gas used is produced by gasification of coal. Circofer process utilizes a combination of circulating and stationary fluidized beds. The fine ores are preheated in a two-stage integrated preheating unit before being admitted to the first reduction stage. The first reduction stage is a circulating fluidized bed reactor, with an integrated heat generator in which the necessary energy is supplied to the system by partial oxidation of coal with oxygen. This partial coal combustion integrated with the circulating fluidized bed system not only produces the heat needed for the process but, specifically, supplies the char required as reducing carbon and anti-sticking agent. With this arrangement it is possible to conduct the circulating fluidized bed pre-reduction at high temperatures of a 950 deg C without prompting a sticking of the fine ores. Iron ore fines and recycled char, from the magnetic separation of the product prior to briquetting, are pre-heated to around 800 deg C in a two-stage circulating fluidized bed system utilizing the off-gas sensible heat from the process. The pre-heated materials are charged into the circulating fluidized bed reactor through a gasifier. Coal is charged directly into the gasifier which operates at a temperature of around 1,000 deg C, where it is oxidized partially with the help of injected oxygen to generate the heat required for the process. The solids and gases enter the circulating fluidized bed, where the iron oxide is reduced at a temperature of around 950 deg C to a metallization degree of around 70 %. Solids from the circulating fluidized bed are transferred to the fluidized bed reactor for the final reduction step to a metallization of around 93 %. The metallized product, ash and excess char are discharged from the fluidized bed reactor, cooled to around 730 deg C and subjected to magnetic separation. The metallized product is hot briquetted at around 680 deg C. The non-magnetic char is recycled back to the process.
Circored process – The process is a natural gas-based process for the production of direct reduced iron from iron ore fines. It is a two-stage fluidized bed process. The first reduction stage is a circulating fluidized bed, the second reduction stage a bubbling fluidized bed reactor. For the heating up of the fine grained direct reduced iron product to briquetting temperature, a flash heater is used. The hydrogen-based Circored process produces highly metalized direct reduced iron or hot briquetted iron for direct feed into electric arc furnace for the steelmaking. The process reduces energy consumption and emissions and offers a sustainable solution for the steelmaking. The special features of the process are (i) direct use of iron ore fines without prior agglomeration, such as pelletizing or sintering, and (ii) operation with pure hydrogen as reducing gas enables reduction with very low carbon di-oxide emission values, and allows the application of low reduction temperatures minimizing sticking tendencies. Hydrogen is produced by means of natural gas reforming, but hydrogen from sources other than a steam reformer, e.g. from water electrolysis, can also be used.
Circular field – It is the magnetic field which (i) surrounds a non-magnetic conductor of electricity, (ii) is completely contained within a magnetic conductor of electricity, or (iii) both exists within and surrounds a magnetic conductor. It is normally applied to the magnetic field within any magnetic conductor resulting from a current being passed through the part or through a section of the part.
Circulating fluidized beds – These beds are popular for large-scale combustion operations, and they are also gaining attention for gasification of carbonaceous feedstocks. Circulating fluidized beds utilize the entire height of tall vessels for gas–solids contacting, with no distinct interface between bed and freeboard. The corresponding flow regime is usually fast fluidization for combustion and gasification of solid fuels. Operating conditions, riser geometry, hydrodynamics, heat transfer, solids feed and particle recirculation all have considerable influence on the operation and effectiveness of the system.
Circulating load – It is the over-sized chunks of ore returned to the head of a closed grinding circuit before going on to the next stage of treatment.
Circulation – It is the movement of water and steam within a steam generating unit.
Circulation ratio – It is the ratio of water entering a circuit to the steam generated by the water which passes that circuit in a unit of time.
Circulator – It is a pipe or tube to pass steam or water between upper boiler drums normally located where the heat absorption is low. It is also used to apply to tubes connecting headers of horizontal water tube boilers with drums.
Civil drawing – It is used for specifying the shape and position of the civil foundation. It typically includes the information such as (i) setting out dimensions for the concrete structure on site, (ii) plans, sections and elevations showing layout, dimensions and levels of all concrete members, (iii) location of all holes, chases, pockets, fixings and other items affecting the concreting work, (iv) notes on specifications, finishes and all cross-references affecting the construction. The drawing provides the detailer with the layout and sectional information required to specify the length, shape and number of each type of reinforcing bar. Reinforcement drawing is part of civil drawing. It fully describes and locates all reinforcements in relation to the finished surface of the concrete and to any holes or fixings. The civil drawing is also a type of technical drawing which shows information about grading, landscaping, or other site details.
Civil engineering – Civil engineering is a professional engineering discipline that deals with the design, construction, and maintenance of the physical and naturally built environment, including public works such as roads, bridges, canals, dams, airports, sewage systems, pipelines, structural components of buildings, and railways.
Clad brazing sheet – It is a metal sheet on which one or both sides are clad with brazing filler metal.
Cladding – It is a layer of material, usually metallic, that is mechanically or metallurgically bonded to a substrate. Cladding can be bonded to the substrate by any of several processes, such as roll-cladding and explosive forming. Cladding also means a relatively thick layer (1 mm) of material applied by surfacing for the purpose of improved corrosion resistance or other properties.
Clad metal – It is a composite metal containing two or more layers which have been bonded together. The bonding can have been accomplished by co-rolling, co-extrusion, welding, diffusion bonding, casting, heavy chemical deposition, or heavy electroplating.
Clad sheet – It is a metal sheet on which one or both sides are clad.
Clamp – It is a fastening device used to hold or secure objects tightly together to prevent movement or separation through the application of inward pressure.
Clamp coupling – A typical clamp coupling essentially consists of two half cylinders which are placed over the ends of the shafts to be coupled and are held together by through bolt.
Clamshell marks – These are macroscopic progression marks on a fatigue fracture or stress-corrosion cracking surface which indicate successive positions of the advancing crack front. The classic appearance is of irregular elliptical or semielliptical rings, radiating outward from one or more origins. These marks (also known as beach marks or arrest marks) are typically found on service fractures where the part s loaded randomly, intermittently, or with periodic variations in mean stress or alternating stress.
Class – As per UNFC (United Nations Framework Classification for Resources) classification, a Class is the primary level of resource classification resulting from the combination of a category from each of the three criteria (axes). A Class is uniquely defined by selecting from each of the three criteria a particular combination of a Category or a Sub-category (or groups of Categories/Sub-categories). Since the codes are always quoted in the same sequence (i.e., E, F, G), the letters can be dropped and just the numbers retained. The numerical code defining a Class is then identical in all languages using Hindu-Arabic numerals.
Classification – Classification is defined as a method of separating mixtures of mineral particles into two or more products according to their settling velocities in water, in air or in other fluids. Classification is performed on the basis of the velocity with which the material particles fall through a fluid medium generally water or air. Classification of minerals follows Stokes’ law of sedimentation. It is also separation of a metal powder into fractions as per particle size.
Classifiers – In classifiers, use is made of the different rates of movement of particles of different sizes and densities suspended in a fluid and differentially affected by imposed forces such as gravity and centrifugal fields, by making suitable arrangements to collect the different fractions as they move to different regions. Based on their separation principles, classifiers are classified into two major types. They are (i) wet classifiers, and (ii) dry classifiers. Wet classification with hydro-cyclones using separation by centrifugal force typically covers the size range of 10 micrometers to 100 micrometers while wet classification with spiral classifiers using separation by gravity typically covers the size range of 100 micrometers to 1000 micrometers. Dry classification using separation by centrifugal force typically covers the range of 5 micrometers to 150 micrometers.
Clay – It is a natural, earthy, fine-grain material which develops plasticity when mixed with a limited quantity of water. Foundry clays, which consist essentially of hydrous silicates of alumina, are used in moulds and cores.
Clays and gums for coating – These materials for electrode coating are to provide elasticity for extruding the plastic coating material and to help provide strength to the coating.
Cleaning – It is the process of chemically or mechanically removing unwanted residue or contaminants (mill scale, rust, dirt, and oil) from the surface of a steel article prior to galvanizing.
Cleaning-emulsifiable solvent – It is a two-stage cleaning system wherein a concentrate containing organic solvents and surface-active agents is applied to a surface, subsequently emulsified, and removed along with the soil, by water rinsing.
Cleaning solutions – These are liquids used to remove unwanted residue or contaminants (mill scale, rust, dirt, and oil) from the surface of steel prior to galvanizing. Cleaning solution can be typically an alkali, caustic solution, hydrochloric acid or sulphuric acid, and zinc ammonium chloride flux solution.
Clean-out door – It is a door placed so that accumulated refuse can be removed from the room in a boiler setting.
Clean steels – These are steels which are obtained after secondary steelmaking and satisfy stringent requirements of surface, internal and micro-cleanliness quality and of mechanical properties. these steels contain limited number of inclusions in terms of size, shape, composition, distribution, and frequency.
Clean surface – It is a surface which is free of foreign material, both visible and invisible.
Clearance – It is the gap or space between two mating parts. It is also the space provided between the relief of a cutting tool and the surface which has been cut. Where galvanized components have to fit together (e.g. hinged items, galvanized bolts), sufficient clearance is to be allowed to accommodate the galvanized coating on each surface. In case of cranes, clearance is the vertical distance between the grade level and the bottom of the crane girder.
Clearance flow – It is the flow which occurs below the minimum controllable flow with the closure member not fully seated.
Clear chill roll – It has a surface layer of white iron produced by inducing rapid cooling at the surface (by means of a chill in the mould) which restricts the formation of free graphite. The core is of grey iron because of the slower rate of cooling and the intermediate zone is a mixture of white iron and grey iron. The necks and wobblers or spade ends are not to be chilled and hence retain greater toughness. The chilled layer is hard and wear resistant but it is brittle. The thickness of the chill varies. It can be even up to 25 mm thick depending upon its application. Beneath the chill zone, there is a transition zone known as ‘Mottle’ zone where carbon is gradually flaking from a few specks to the full flake. The core portion is grey iron. Hardness drops down if the chill is worn out. The chilled layer thickness can be increased where shallow grooves are needed.
Clear solution – It refers to a liquid mixture where the solute is completely dissolved in the solvent, creating a transparent and homogeneous mixture. This type of solution is characterized by its lack of visible particles or sediment.
Clear span – It is the distance between columns across the width of the building. Building width is defined as the distance from outside of the eave strut of one sidewall to outside of the eave strut of the opposite sidewall. Crane span is the horizontal centre distance between the rails of the runway on which the crane is to travel. Typical distance is around 500 mm less than the width of the building. The requirement of the span of the crane depends on the crane coverage width dictated by the application.
Cleavage – It is the fracture of a crystal by crack propagation across a crystallographic plane of low index. It is also the tendency to cleave or split along definite crystallographic planes.
Cleavage crack – It is a crack which extends along a plane of easy cleavage in a crystalline material.
Cleavage fracture – It is a fracture, normally of a polycrystalline metal, in which majority of the grains have failed by cleavage, resulting in bright reflecting facets. It is one type of crystalline fracture and is associated with low-energy brittle fracture.
Cleavage plane – It is a characteristic crystallographic plane or set of planes in a crystal on which cleavage fracture occurs easily.
Cliff edge effect – It is a significant consequence which is disproportionate to the change that caused it.
Climb cutting – It is analogous to climb milling.
Climb milling – It is milling in which the cutter moves in the direction of feed at the point of contact.
Close annealing – It is annealing a metal or alloy in a sealed container under conditions which minimize oxidation. In box annealing a ferrous alloy, the charge is normally heated slowly to a temperature below the transformation range, but sometimes above or within it, and is then cooled slowly. This process is also called box annealing or pot annealing.
Closed die forging – It is performed by squeezing the raw material called billet inside the cavity formed between a pair of shaped dies. Forged products achieve the shape of the die cavity. Valve parts, pump parts, small gears, and connecting rods, spanners etc. are produced by closed die forging.
Closed belt conveyor – In a closed belt conveyor, the specially fabricated belt, after being loaded with the material, can be wrapped completely around the load. It essentially forms a closed tube moving along with the material. The advantages of a closed belt conveyor are (i) it can handle fragile materials safely and without breaking by reducing inter-particle collision, (ii) it can handle fine bulk materials without being swept by air though, it is not really air tight at loading and unloading points, (iii) it has ability to handle corrosive and reactive materials without contamination, and (iv) the tubed belt can travel around bends in more than one plane and hence versatile in layout. The lengths of these conveyors are normally limited.
Closed-die forging – It is the shaping of hot metal completely within the walls or cavities of two dies which come together to enclose the work-piece on all sides. The impression for the forging can be entirely either die or divided between the top and bottom dies. Impression-die forging, frequently used interchangeably with the term closed-die forging, refers to a closed-die operation in which the dies contain a provision for controlling the flow of excess material, or flash, that is generated. By contrast, in the flash-less forging, the material is deformed in a cavity which allows little or no escape of excess material.
Closed dies – These are forging or forming impression dies designed to restrict the flow of metal to the cavity within the die set, as opposed to open dies, in which there is little or no restriction to lateral flow.
Closed-loop control – Closed-loop control of a system offers the possibility to dynamically adjust its inputs in order to follow a reference set point, and to reduce the effect of the perturbations from the system’s environment. Closed-loop control is achieved by adding more complexity to the system, and this makes it more vulnerable. Digital controllers have to be added and tuned, so are sensors, which are needed to close the loop. But the benefits in terms of robustness and improved performance, e.g., efficiency, always justify the cost, provided that a clear and systematic methodology can be adopted to design the control.
Closed pass – It is a pass of metal through rolls where the bottom roll has a groove deeper than the bar being rolled and the top roll has a collar fitting into the groove, hence producing the desired shape free from flash or fin.
Closed system – It is a thermodynamic system which undergoes no interchange of mass (materials) with its surroundings. A closed system, however, can interchange energy with its surroundings.
Close-packed – It is a geometric arrangement in which a collection of equally sized spheres (atoms) can be packed together in a minimum total volume.
Close tolerance – Close tolerance refers to the application of precise geometrical requirements on engineering drawings, especially for surfaces which interact with other parts, when tight tolerances are necessary to ensure proper functionality and repeatability.
Close-tolerance forging– It is a forging held to unusually close dimensional tolerances so that little or no machining is needed after forging.
Closure member – It is the movable part of the valve which is positioned in the flow path to modulate the rate of flow through the valve.
Closure member guide – It is that portion of a closure member which aligns its movement in either a cage, seat ring (port guiding), bonnet, bottom flange, stem, or any two of these.
CLU process – CLU process is similar to the AOD (argon oxygen decarburization) process for making stainless steels. CLU refers to the Creusot-Loire Uddeholm process for stainless steel production. It also uses liquid steel from an electric arc furnace or any other similar primary steel making furnace. The major impetus for the development of the CLU process was the idea to use superheated steam as the diluting gas instead of argon gas which is used in the AOD process. It is carried out either in a bottom blown converter or a side blown converter.
Cluster analysis – This method is used to classify objects or individuals. For this purpose, mutual groups are constructed to maximize both the homogeneity and heterogeneity between clusters. Factor analysis groups variables as factors, while the cluster method groups objects or people together by considering different criteria.
Cluster mill – It is a rolling mill in which each of the two working rolls of small diameter is supported by two or more larger diameter back-up rolls.
Cluster mill roll configuration – In this type of roll configuration, there are six, seven, twelve, or twenty horizontally mounted rolls. In all the mills having this configuration, there are only two rolls which are work rolls while all the other rolls are back-up rolls. Normally work rolls are driven and back-up rolls are friction driven. The multi-roll mill configuration is used for cold rolling of very thin sheets, strips and foils.
Clutch – It is a mechanical device which allows an output shaft to be disconnected from a rotating input shaft. The clutch’s input shaft is typically attached to a motor, while the clutch’s output shaft is connected to the mechanism that does the work.
Clutch and brake shears – These are of an older design, but can benefit from new automation, though accuracy and repeatability are limited by clutch and brake system performance. The main advantage of this type of the shear is the possibility of fine-tuning clutch and brake timing to optimize accuracy and friction material life.
CO2 process – It is the process by which moulds and cores, made with sand containing sodium
Silicate, are hardened by permeating the sand with carbon di-oxide gas.
Coal – It is a combustible compact black or brownish black sedimentary rock normally occurring in rock strata in layers or veins called coal beds or coal seams. It is a complex combination of organic matter and inorganic ash formed over eons from successive layers of fallen vegetation. It is composed primarily of carbon along with varying amounts of other elements mainly hydrogen, oxygen, nitrogen and sulphur. It is normally classified for convenience into four categories. These categories are (i) lignite or brown coal, (ii) sub bituminous coal, (iii) bituminous coal, and (iv) anthracite.
Coal ash – It is the mineral matter present in the coal. It is a waste which is left after coal is combusted (burned). It is the particulate material which remains after coal is burned. It includes fly ash (fine powdery particles which are carried up the smoke stack and captured by pollution control devices) as well as coarser materials which fall to the bottom of the furnace. It has different physical and chemical properties depending on the geochemical properties of the coal being used and how that coal is burned.
Coal chemicals -These are the chemicals which are produced as by-products in the process of the ‘destructive distillation’ of various blends of bituminous coal.
Coalescence – It is the union of particles of a dispersed phase into larger units, normally effected at temperatures below the fusion point. It is also the growing together or growth into one body of the materials being welded. It also means growth of grains at the expense of the remainder by absorption or the growth of a phase or particle at the expense of the remainder by absorption or reprecipitation.
Coal explosibility – Explosibility of coals is determined by measuring the length of flame when the dry pulverized coal of one gram with size under 0. 074 mm is injected to a fire source at 1050 deg C. If there is no flame near the fire source then the coal has no explosibility. If the length of flashback in glass tube is less than 400 mm, then the coal is combustible and explosive, otherwise the coal has strong explosibility.
Coal gasification process – It is based on the fundamental principle of partial combustion of coal. The gas which comes out after partial combustion is called raw syngas which is purified further in processing units before it is used. Coal gasification is carried out with limited quantity of oxygen which is around one-fifth to one-third of the theoretically oxygen needed for complete combustion. Only a fraction of carbon is burned for generation of heat. Hydrogen and carbon mono-oxide are the main products of gasification. Methane and carbon di-oxide are other two major products and their content goes up with increasing pressure with hydrogen and carbon mono-oxide content going down. In coal gasifiers two physico-chemical processes take place. They are (i) pyrolysis or devolatilization process, and (ii) gasification process. In the pyrolysis process, as the coal enters into the gasifier, it is first dried by the hot gases present in the gasifier. A series of complex physical and chemical process start slowly at temperature less than 350 deg C and accelerate as temperature exceeds 700 deg C. The composition of the released products of pyrolysis is dependent on the temperature, pressure and gas composition during pyrolysis. The pyrolysis process can be represented by the reaction Coal –> Heat –> Char –> Gases –> Vapours or liquid. The three products which are produced by pyrolysis are (i) light gases such as hydrogen, carbon mono-oxide, methane, carbon di-oxide, water vapour, (ii) tar which is a corrosive and viscous liquid composed of heavy inorganic and organic molecules, and (iii) char which is a solid residue mainly contains carbon. The gasification process involves a series of endothermic reactions which are supported by the heat produced from the combustion reactions occurring inside the gasifier. These reactions are represented by the equations (i) C + O2 = CO2 with delta H = -94.05 kcal/mol, and (ii) H2 + 0.5 O2 = H2O with delta H = – 68.3 kcal/mol. The major gasification reactions which take place are (i) water gas shift reaction, (ii) Boudouard reaction, (iii) shift conversion, and (iv) methanation.
Coalification – It is the metamorphic processes of forming coal.
Coal moisture analyzer – A number of moisture measurement systems are available. However, the reliable method to measure the coal moisture on-line is to use ‘microwave with area weight compensation’. Microwaves are a highly accurate way to measure moisture due to the fact that microwaves are highly selective to water. They penetrate the material to be measured. Water molecules are naturally polar which causes the microwaves to weaken and slow down significantly.
Coal rank – Coals are classified by rank according to their progressive alteration in the natural metamorphosis from lignite to sub bituminous coal to bituminous coal and to anthracite. Ranking is determined by the degree of transformation of the original plant material to carbon. Coal rank depends on the volatile matter, fixed carbon, inherent moisture, and oxygen, although no one parameter defines rank. Typically coal rank increases as the amount of fixed carbon increases and the amount of volatile matter decreases.
Coal tar – It is a by-product generated during the high temperature carbonizing of coking coal for the production of the metallurgical coke in the by-product coke ovens. It is a black, viscous, sometimes semi-solid, fluid of peculiar smell, which is condensed together with aqueous ‘gas-liquor’ (ammoniacal liquor), when the volatile products of the carbonization of coking coal are cooled down. Composition is variable, but normally consists of 0 % to 2 % of light oils (chiefly benzene, toluene, and xylene), 16 % to 18 % of middle oils (chiefly phenols, cresols, and naphthalene), 8 % to 10 % heavy oils (naphthalene and derivatives), 16 % to 20 % anthracene oils, and around 50 % pitch. It is composed primarily of a complex mixture of condensed-ring aromatic hydrocarbons. It can contain phenolic compounds, aromatic nitrogen bases and their alkyl derivatives, and paraffinic and olefinic hydrocarbons.
Coal tar distillation process – Fractional distillation process is used for the distillation of coal tar. Fractional distillation of tar refers to the process by which components in a chemical mixture are separated by taking advantage of the difference in their boiling points. Distillation of coal tar is carried out mainly to produce benzole, naphtha, creosotes, naphthalene, anthracene, carbolic and cresylic acids, pyridine and pitch. The purpose of tar distillation is to (i) dehydrate the tar in the dehydration column, (ii) remove the pitch from dehydrated tar in pitch column and (iii) separate tar oils in fractionating column. Since the quality of the coal tar is dependent on the coal carbonizing process and since there are large numbers of chemical compounds available in coal tar, the design and composition of the tar distillation plant varies with the type of tar and the compounds which are required to be distilled. Hence, it is very rare that the two tar distillation plants are exactly similar.
Coal tar pitch – It is a dark-brown-black, shiny, amorphous residue produced during the distillation of coal tars. It is composed of many different compounds which interact to form eutectic mixtures and thus it does not show a distinct melting or crystallization point. Rather, it is characterized by a softening point (the temperature at which a given viscosity is reached). Depending upon the extent of distillation, pitches of different softening point can be obtained. Examples are medium soft pitch or very hard pitch. It is the preferred material for use as a binder in the manufacture of carbon and graphite electrodes.
Coarse grains – These are grains larger than normal for the particular wrought metal or alloy or of a size which produces a surface roughening known as orange peel or alligator skin.
Coarsening – It is an increase in grain size, normally, but not necessarily, by grain growth.
Coated abrasive – It an abrasive product (sand-paper, for example) in which a layer of abrasive particles is firmly attached to a paper, cloth, or fibre backing by means of glue or synthetic-resin adhesive.
Coated abrasive product – It is a two-body abrasion device in which a backing paper or cloth is coated with a layer of abrasive grits, which are cemented to the backing.
Coated cold rolled flat products – These are the flat products with a permanent coating. The permanent coatings can be either on both sides or only on one side. In case of coating on both the sides, it can be either equal thickness coating on each side or of different thickness of coating on each side known as differential coating.
Coated electrode – A composite filler metal electrode consisting of a core of a bare electrode or metal cored electrode to which a covering sufficient to provide a slag layer on the weld metal has been applied. The covering can contain materials providing such functions as shielding from the atmosphere, deoxidation, and arc stabilization and can serve as a source of metallic additions to the weld. The preferred terms for coated electrode are covered electrode and lightly coated electrode.
Coating – It is a relatively thin layer (less than 1 mm) of material applied by surfacing for the purpose of corrosion prevention, resistance to high-temperature scaling, wear resistance, lubrication, or other purposes.
Coating blister – it is a raised area, frequently dome shaped, resulting from loss of adhesion between a coating or deposit and the substrate.
Coating, conversion – It is an inorganic pretreatment sometimes applied to a metal surface to improve coating adhesion and to retard corrosion.
Coating density – It is a non-standard term for spray deposit density ratio which is the ratio of the density of the spray deposit to the theoretical density of a surfacing material, normally expressed as a percent of theoretical density.
Coating drip – It is a nonuniform extraneous deposit of coating on the coated sheet.
Coating, high or low – It means failure of the coating to meet the agreed-upon thickness limits measured in weight per unit area.
Coating mass – Galvanized coatings are generally specified in terms of coating mass, in grams per square metre, on the surface of the steel. For ease of measurement, the thickness of a galvanized coating is measured in micrometers using non-destructive techniques. One micrometer in thickness is around 7 grams per square metre in coating mass.
Coating strength – It is a measure of the cohesive bond within a coating, as opposed to coating-to-coating substrate bond. It is the tensile strength of a coating.
Coating stress – It is the stresses in a coating resulting, e.g., from rapid cooling of molten or semi-molten
particles as they impact the substrate or from differential thermal expansion.
Coating thickness – It is the thickness of the zinc coating, measured in micrometers. The hot dip galvanized coating thickness is determined by galvanizing bath chemistry, steel chemistry, steel surface condition, and steel section thickness. National standards normally define minimum acceptable coating thickness for a range of steel sections.
Coaxial valve – It works by utilizing an internal, axially movable hollow tube, which can either control or divert the flow of media passing through the valve. Coaxial valves are valves known for fast switching times combined with high working pressures and are used to control the flow of liquids or gases. The valves are ideal for high viscosity media.
Coaxial solenoid valve– It is a direct-acting solenoid valve with an unobstructed flow route for very viscous media or high-pressure applications.
Coaxing – It is improvement of the fatigue strength of a sample by the application of a gradually increasing stress amplitude, normally starting below the fatigue limit factors’, rather than identifying ‘the cause’.
Cobalt – Cobalt (atomic number 27 and atomic weight 58.94) has density of 8.85 grams per cubic centimeter. Its melting point is 1493 deg C and boiling point is 3100 deg C. It increases strength and hardness, and permits quenching at higher temperatures. In some steels used for nuclear engineering, cobalt is an undesirable impurity, even in quantities as low as 0·02 %. Unlike most other alloying elements, cobalt reduces hardenability. It raises the red hardness of the steel and this is the reason 5 % to 10 % of cobalt is added to certain types of high speed steels, developed for the specific purpose of cutting exceptionally hard materials. Heat resisting alloys with high cobalt contents have been developed for use in gas turbines. Cobalt is added to the extent of up to 40 % to magnet steels requiring high coercive force and it is used in electrical- resistance alloys. In the sintered hard metals cobalt acts as the binding metal.
Cobble – It happens because of misroll. Misroll is a phenomenon in rolling mills in which the running material, for some reason, misses the proceeding pass and rolls down at the same place, causing the material to become waste. It causes jamming of the mill by the product while being rolled. It is also a piece of product, which for any reason has become so bent or twisted that it is to be withdrawn from the rolling operation and scrapped.
Cock valve – It is a type of valve which is used to control the flow and supply of fluids such as water, oil, or gas. It consists of a cylindrical chamber which contains a movable plug known as ‘cock’, which serves as an inlet and outlet for controlling fluid flow. The cock can be opened or closed to regulate the rate at which fluid passes through it. Cock valves are highly reliable and easy to install and maintain, making them ideal for many industrial applications.
Cocoa – In fretting wear, it is a powdery form of debris, normally consisting of iron oxides, which is expelled from a ferrous metal joint near the location where fretting wear is occurring.
Code of practice – It is a body of rules for practical guidance only and not having the force of law although failure to comply can be used in evidence in legal proceedings.
Coefficient of compressibility – It signifies decrease in void ratio per unit increase in effective stress. It is slope of void ratio against effective stress curve. It represents magnitude of volume change or settlement.
Coefficient of friction – It is the dimensionless ratio of the friction force (F) between two bodies to the normal force (N) pressing these bodies together.
Coefficient of thermal expansion – It is the change in unit of length (or volume) accompanying a unit change of temperature, at a specified temperature. It is also the linear or volume expansion of a given material per degree rise of temperature, expressed at an arbitrary base temperature or as a more complicated equation applicable to a wide range.
Coercive force – It is the magnetizing force which is to be applied in the direction opposite to that of the previous magnetizing force in order to reduce magnetic flux density to zero, hence, a measure of the magnetic retentivity of magnetic materials.
Coextrusion welding – It is a solid-state welding process which produces coalescence of the faying surfaces by heating and forcing base metals through an extrusion die.
Cogging – It is the reducing operation in working an ingot into a bloom or slab in a cogging mill or into a billet with a forging hammer or a forging press.
Cogging mill – It is a blooming mill or a slabbing mill.
Coherent precipitate – It is a crystalline precipitate which forms from solid solution with an orientation which maintains continuity between the crystal lattice of the precipitate and the lattice of the matrix, normally accompanied by some strain in both lattices. Since the lattices fit at the interface between precipitate and matrix, there is no discernible phase boundary.
Coherent scattering – It is a type of x-ray or electron scattering in which the phase of the scattered beam has a definite (not random) relationship to the phase of the incident beam.
Cohesion – It is the state in which the particles of a single substance are held together by primary or secondary valence forces. As used in the adhesive field, the state in which the particles of the adhesive (or adherend) are held together. It also means force of attraction between the molecules (or atoms) within a single phase.
Cohesive strength – It is the hypothetical stress causing tensile fracture without plastic deformation. It is also the stress corresponding to the forces between atoms.
Cohesive zone – Cohesive zone is the region lower down the blast furnace. Here, slag starts to form at around 1,100 deg C. Initially it is relatively viscous, and surrounds the iron oxide particles, preventing further reduction. As the temperature increases to level of around 1,400 deg C to 1,450 deg C, it melts and reduction continues. This region is critical in terms of burden permeability.
Coil – It is an assembly consisting of one or more magnet wire windings. It is also the form in which rolled metal sheet, strip or wire rod is produced.
Coiler – It is sometimes called recoiler. It is an auxiliary equipment in the hot strip mill and cold rolling mill used for coiling hot-rolled or cold-rolled steel strip into a roll shape. It is arranged behind the last finishing stand on the hot strip mill (hot strip mill), cold rolling mill.
Coil breaks – These are creases or ridges in sheet or strip which appear as parallel lines across the direction of rolling and which normally extend the full width of the sheet or strip.
Coil curvature – It is the longitudinal bow in an unwound coil in the same direction as curvature of the wound coil. It is also known as coil set.
Coiling machines – Coiling machines are used to wound long rolled products into coils. Making coils of the rolled products facilitates handling and improves the yield.
Coil orientation, clockwise coil – It means that with the coil core vertical (eye to the sky) and viewed from above, a trace of the metal edge from the inside diameter to the outside diameter involves clockwise movement.
Coil orientation, counterclockwise (anticlockwise) coil – It means that with the coil core vertical (eye to the sky) and viewed from above, a trace of the metal edge from the inside diameter to the outside diameter involves counter-clockwise (anti-clockwise) movement.
Coil reforming chamber – For ensuring the optimum coil package, the coil is to be formed in an orderly manner and also completely formed inside the upper portion of the coil reforming chamber. The ordering of the rings coming off the exit section is achieved with a ring distributor, which is a proven design of rotating blade within the upper portion of the chamber which directs how the rings fall onto the forming coil. The reform ring distributor collects rings high in the reforming chamber using a rotating blade for optimal placement. This system shortens the coil package, easing shipping, and storage space concerns, which in turn reduces costs. Improved collection also results in better-shaped coils for fewer tangles and snags at pay-off.
Coil set – It is the longitudinal bow in an unwound coil in the same direction as curvature of the wound coil. It is also known as coil curvature.
Coil set differential – It is the difference in coil set from edge to edge of a coiled sheet sample. It is measured with the sample on a flat table, concave side up, and is the difference in elevation of the comers on one end.
Coil set, reversed – It is the longitudinal bow in an unwound coil in the direction opposite the curvature of the wound coil.
Coil spring – It is also known as helical spring. It is made by winding a wire around a cylinder or a cone. In case wire is wound on a cone then the spring is called a conical spring. Coil springs are usually of two types. The first type consists of a compression spring which is designed to become shorter when loaded. Their turns (loops) are not touching in the unloaded position, and they need no attachment points. A volute spring is also a compression spring in the form of a cone, designed so that under compression the coils are not forced against each other, thus permitting longer travel. The second type consists of tension or extension springs which are designed to become longer under load. Their turns (loops) are normally touching in the unloaded position, and they have a hook, eye or some other means of attachment at each end.
Coiled sheet – It is the sheet in coils with slit edges.
Coiling of spring wire – it can be done either by cold winding or hot winding. In case of cold winding the steel wire (normally up to 18 mm diameter) is coiled at room temperature using one of two basic techniques. One consists of winding the wire around a shaft called an arbour or mandrel. In the second technique, the wire can be coiled without a mandrel. This is normally done with a CNC machine. In case of hot winding, thicker wire or round bar can be coiled into springs by heating the steel to make it flexible. Standard industrial coiling machines can handle steel bar up to 75 mm in diameter, and custom springs have reportedly been made from bars as much as 150 mm thick. The steel is coiled around a mandrel while red hot.
Coining – Coining is the process of applying compressive stress on surface of the raw material in order to impart special shapes on to the surface from the embossing punch, e.g., coins, and medallions. It is a closed-die squeezing operation, normally performed cold, in which, all the surfaces of the work are confined or restrained, resulting in a well-defined imprint of the die upon the work. It is also a restriking operation used to sharpen or change an existing radius or profile. It also means the final pressing of a sintered powder metallurgy compact to get a definite surface configuration.
Coining dies – These are the dies in which the coining or sizing operation is performed.
Coin silver – It is an alloy containing 90 % silver, with copper being the normal alloying element.
Coin straightening – It is a combination coining and straightening operation performed in special cavity dies designed to impart a specific amount of working in specified areas of a forging to relieve the stresses developed during heat treatment.
Coke – It is a hard porous carbon material produced in the process of the ‘destructive distillation’ of various blends of bituminous coal, petroleum, or coal tar pitch which drives off most of the volatile matter. It has a multiple role. It is a reducing agent, source of reducing carbon mono-oxide gas, a source of heat, a filter of dust and soot, and a carburizer of hot metal, besides supporting the burden and providing gas permeability. It has several uses.
Coke ash – Coke ash is the mineral matter present in the coke. Metallurgical coke typically contains around 8 % to 12 % of mineral phases. The proportion of individual minerals present in coke can vary from coke to coke depending on the mineralogy of the original coals as well as the process conditions employed for carbonization.
Coke bed – It is the first layer of coke placed in the cupola. Also, it is the coke used as the foundation in constructing a large mould in a flask or pit.
Coke breeze – It is the fines (-10 millimeters) from coke screenings. It is use in sintering of ores, in blacking mixes after grinding, and is also briquetted for cupola use.
Coke furnace – It is a type of pot or crucible furnace which uses coke as the fuel.
Coke micro-texture – The micro-texture of coke is the organization of the material at the intermediate scale from the nano-metric (nm) to the micro-metric (micron) scale. Micro-texture is the result of the mutual orientation in space of poly-aromatic ‘basic structural units’ (BSU) with size about 1 nm (nano metre), formed by poly-aromatic layers (4 to 10 rings) stacked by 2 or 3. Coke is composed of differently sized ‘molecular orientation domain’ (MOD) as coals are generally chemically heterogeneous. Coke micro-texture can be characterized by the distribution of MOD sizes varying from 5 nm to a few micrometers (microns).
Coke reactivity – Coke reactivity is one of the most important factors which control the bed permeability in the blast furnace The lower the coke reactivity the higher is the permeability of the burden in the BF. The coke reactivity is influenced by its three major properties of coke namely (i) micro-texture which determine the number of active sites, (ii) micro-structure which controls diffusion and chemical rates, and (iii) constituent minerals which can have a catalytic effect.
Coke oven gas – It is a by-product gas produced during the production of metallurgical coke in a by-product coke oven battery, where metallurgical coal is carbonized by heating it in absence of air. It is a colourless gas with an odour characteristics of hydrogen sulphide and hydrocarbons. Its major constituents are hydrogen, methane, and carbon mono-oxide. It has a calorific value ranging between 17 mega-joules to 19 mega-joules per normal cubic meter. It has a theoretical flame temperature of 1982 deg C. It has a rate of flame propagation which allows its actual flame temperature to be close to its theoretical flame temperature.
Coke oven machines – These machines are an integral part of any coke oven battery. These machines charge the ovens with the coal feedstock, push the coke from the ovens after coking, and feed it to the coke quenching process. The different types of coke oven machines are (i) coal charging car, (ii) coke pusher machine for the top charged ovens, (iii) coal stamping cum coke pusher machine for stamped charge ovens, (iv) coke guide and transfer car, (v) coke quenching car or coke bucket car with electric locomotive, and (vi) door service car.
Coke rate – Coke rate is the parameter for the consumption of blast furnace coke. It is measured in kilograms of blast furnace coke consumed per ton of hot metal produced.
Coking coal – It is a type of bituminous coal. The term ‘coking coal’ is used to designate certain types of bituminous coals which, when heated at high temperatures (over 1,000 deg C) in the absence of air (carbonization), soften, liquefy, and then re-solidify into a hard but porous mass known as coke. Coking coal is also referred as ‘metallurgical (met) coal’. The mean maximum reflectance (MMR) values for the coking coals in case of low volatile coals are normally in the range of 1.42 % to 1.75 %, in case of medium volatile coals normally in the range of 1.05 % to 1.4 %, and in case of high volatile coals normally in the range of 0.70 % to 1.02 %.
Cold blast valve – Cold blast valve is intended for the complete separation of the blast furnace stove from the cold blast main. It is installed on the horizontal cold blast main near the stove. These valves are normally not lined since the temperature of the cold blast is normally in the range of 150 deg C to 250 deg C, which is the temperature resulting from the heat of compression at the blower.
Cold bond briquetting – It is an important process which is used to recycle and utilize the plant waste by-products of fine particle size. The briquetting process converts the fine particles into cold bonded briquettes. In this process, different waste by-products are agglomerated using very small quantity of the binder. The briquetting process avoids heating up, softening, and melting the fine particles, which saves a lot of fossil energy and decreases the environmental pollution.
Cold box process – In foundry practice, it is a series casting sand core production process based on a reaction between sand and resins at room temperature, accelerated by a catalyst. This process utilizes a two-part binder system, typically consisting of phenolic urethane (a resin) and a catalyst (such as an amine gas). The sand mixture is blown into the core box, and the catalyst is introduced to the resin-coated sand, leading to rapid curing and hardening of the core.
Cold briquetted iron (CBI) – It is direct reduced iron which has been briquetted when it is cooed after its discharge from the furnace.
Cold chamber machine – It is a die casting machine with an injection system which is charged with liquid metal from a separate furnace.
Cold coined forging – It is a forging which has been restruck cold in order to hold closer face distance tolerances, sharpen corners or outlines, reduce section thickness, flatten some particular surface, or, in the non-heat-treatable alloys, increase hardness.
Cold compacting – This is the standard compaction method under which the metal powder mix is compacted without sintering to a green body at room temperature.
Cold crack – It is a crack which develops after solidification is complete.
Cold cracking – It consists of forming cracks in cold or nearly cold cast metal because of the excessive internal stress caused by contraction. It is frequently brought about when the mould is too hard or the casting is of unsuitable design. In welding, it is a type of weld cracking which normally occurs below 205 deg C. Cracking can occur during or after cooling to room temperature, sometimes with a considerable time delay. Three factors combine to produce cold cracks namely stress (for example, from thermal expansion and contraction), hydrogen (from hydrogen-containing welding consumables), and a susceptible microstructure (plate martensite is most susceptible to cracking, ferritic and bainitic structures are least susceptible).
Cold crushing strength – It is a measure of the mechanical strength of the refractory brick. In furnaces, cold crushing strength is of importance, because of bricks with high crushing strength is more resistant to impact from rods or during removal of slag than a brick with a low cold crushing strength. It is a useful indicator to the adequacy of firing and abrasion resistance in consonance with other properties such as bulk density – and porosity.
Cold die quenching – It is a quenching which utilizes cold, flat, or shaped dies to extract heat from a part. Cold die quenching is slow, expensive, and is limited to smaller parts with large surface areas.
Cold direct reduced iron (CDRI) – It is the direct reduced iron which is discharged from the furnace in cold condition (temperature around 50 deg C).
Cold etching – It is the etching to reveal micro-structure which is conducted at room temperature and below.
Cold extrusion – Cold extrusion of metals involves forcing the material through a die at room temperature for creating a continuous product of consistent cross-section. Cold extrusion is so called since the billet / slug or preform enters the extrusion die at room temperature. During the process, however, the deforming material undergoes deformation heating (conversion of deformation work to heat) to several hundred degrees. Typically, a punch is used to apply pressure to the billet enclosed, partially or completely, in a stationary die. Cold extrusion is a forging operation which has the typical advantages of material savings, work-hardening (strengthening), and grain flow or directional strengthening. Cold extrusion involves backward (indirect), forward (direct), or combined backward and forward (indirect-direct) displacement of metal by plastic flow under steady, though not uniform, pressure.
Cold finger – It is a liquid-nitrogen-cooled cold trap used to reduce contamination levels in vacuum chambers.
Cold forming – It is a metal working process in which metal is shaped below its recrystallization temperature, normally at the ambient temperature. Cold forming techniques are normally classified into four major groups namely squeezing, bending, drawing, and shearing. They normally have the advantage of being simpler to carry out than hot working techniques.
Cold galvanizing – It is the process used to touch up and / or repair hot dipped galvanized surfaces and providing barrier protection as well as some cathodic protection.
Cold heading – It consists of working metal at room temperature such that the cross-sectional area of a portion or all of the stock is increased.
Cold heading quality steels – These are quality of steels used for making of fasteners by cold heading process. The steel is to be very clean and without any internal or external defects.
Cold inspection – It is a visual (normally final) inspection of forgings for visible imperfections, dimensions, weight, and surface condition at room temperature. The term can also be used to describe certain nondestructive tests such as magnetic-particle, dye-penetrant, and sonic inspection.
Cold isostatic pressing (CIP) – It is a forming technique in which high fluid pressure is applied to a powder (metal or ceramic) part at ambient temperature. Water or oil is used as the pressure medium.
Cold lap – It consists of wrinkled markings on the surface of an ingot or casting from incipient freezing of the surface and too low a casting temperature. It is also a flaw which results when a work-piece fails to fill the die cavity during the first forging. A seam is formed as subsequent dies force metal over this gap to leave a seam on the work-piece surface.
Cold pressing – It consists of forming a powder metallurgy compact at a temperature low enough to avoid sintering, normally room temperature.
Cold rolled steels – These are sheet steels which have been pickled and run through a cold rolling mill. A cold rolled strip has a final product width of around 300 mm, while sheet can be more than 2000 mm wide. Cold-rolled sheet is considerably thinner and stronger than hot-rolled sheet.
Cold-rolled sheets – It is a metal mill product produced from a hot-rolled pickled coil which has been given substantial cold reduction at room temperature. The resulting product normally needs further processing to make it suitable for the majority of the common applications. The normal end product is characterized by improved surface, higher uniformity in thickness, and improved mechanical properties compared with hot rolled sheet.
Cold rolled strip – Cold rolled strip is the flat product which, immediately after the final rolling pass is wound into a coil. Cold rolled strip as rolled has slightly convex edges, but it can also be with sheared edges or slit from wider strip.
Cold rolling mill – It is a mill for cold rolling of sheet or strip.
Cold-setting process – In foundry practice, it consists of any of several systems for bonding mould or core aggregates by means of organic binders, relying on the use of catalysts rather than heat for polymerization (setting).
Cold shears – These shears are for cutting of cooling bed lengths into saleable lengths. They are installed downstream of the cooling bed exit roller table after the straightener. Cold shears can also be flying shears.
Cold shortness – It is brittleness which exists in some metals at temperatures below the recrystallization temperature.
Cold shot – It is a portion of the surface of an ingot or casting showing premature solidification. It is caused by splashing of molten metal onto a cold mould wall during pouring. It is also small globule of metal embedded in, but not entirely fused with, the casting.
Cold shut – It is a linear discontinuity which appears on the surface of cast metal as a result of two streams of liquid meeting and failing to merge prior to solidification. It is also a lap on the surface of a forging or billet which has been closed without fusion during deformation. It is freezing of the top surface of an ingot before the mould is full. It is a forging defect developed by metal flowing into a section from two directions, resulting in a discontinuity at the junction.
Cold soldered joint – It is a joint with incomplete coalescence caused by insufficient application of heat to the base metal during soldering.
Cold-stream process – In powder metallurgy, it is a method of producing cleavage fractures in hard particles through particle impingements in a high-velocity cold gas stream. It is also referred to as impact crushing.
Cold treatment – Cold treatment of steel consists of exposing the ferrous material to sub-zero (- 85 deg C) temperatures to either impart or improve specific conditions or properties of the material. Increased strength, greater dimensional or microstructural stability, improved wear resistance, and relief of residual stress are among the benefits of the cold treatment of steel. Normally, 1 hour of cold treatment for every 25 mm of cross section is adequate to achieve the desired results. When the treatment involves the transformation of retained austenite, it is normally followed by tempering.
Cold trimming – It is the removal of flash or excess metal from a forging at room temperature in a trimming press.
Cold welding – It is a solid-state welding process in which pressure is used at room temperature to produce coalescence of metals with substantial deformation at the weld.
Cold work – It is permanent strain in a metal accompanied by strain hardening.
Cold-worked structure – It is a micro-structure resulting from plastic deformation of a metal or alloy below its recrystallization temperature.
Cold working – It is deforming metal plastically under conditions of temperature and strain rate which induce strain hardening. Normally, but not necessarily, it is conducted at room temperature. Cold working induces stresses which can be released during the galvanizing process.
Cold work tool steels – These tool steels have high strength, hardenability, impact toughness, and wear resistance. These steels can be oil hardening type, air hardening medium alloy type, or high carbon high chromium type. These steels are used in those working conditions where operating temperatures are typically less than 200 deg C. These tool steels are used on larger parts or those parts which need minimal distortion during hardening. The use of oil quenching and air hardening helps reduce distortion as opposed to higher stress caused by quicker water quenching. More alloying elements are used in these steels, as compared to water-hardening grades. The alloys in these steels increase the steel’s hardenability, and hence need a less severe quenching process. These steels are also less likely to crack. Typical applications include cold working operations such as stamping dies, draw dies, burnishing tools, coining tools, and shear blades.
Coldry technology – It is a process which changes the naturally porous form of low rank coals to produce a dry and dense pellets by a process which is called as ‘brown coal densification’(BCD). The Coldry process combines two unique aspects namely (i) brown coal densification, and (ii) waste heat utilization. The drying process is based on the release of moisture in the coal, by initiating an exothermic reaction, because of the abrasion of the carbon particles together. The result is a concentrated product in the form of densified pellets which are durable, easy to store and transport, and which have similar energy value normally associated with several of the black coals, whilst significantly reducing carbon di-oxide emissions compared to its original brown coal form. The process consists of six steps namely (i) screening and feed control, (ii) attritioning and extruding, (iii) conditioning, (iv) pack bed drying, (v) water recovery, (vi) production of Coldry pellets. The process stimulates a natural chemical reaction within the coal. This reaction polymerizes active sites in the coal compounds and expels chemically bound water. The polymerization of the active sites collapses the coal pore structure and expels the physically trapped water. The ejected water migrates to the surface of the coal pellets. The surface water is evaporated by the utilization of waste heat.
Collapse – It is the out-of-round condition of coil frequently because of the inappropriate tension during rewinding operations.
Collapsibility – It is the tendency of a sand mixture to break down under the pressures and temperatures developed during casting.
Collars – These are ring-shaped metal devices which clamp around a shaft. The purpose of the collar is normally to hold motor components, gear assemblies, sprockets, bearings, and other parts in place and sometimes facilitate their proper movement.
Collector – It is a device used for removing gas borne solids from flue gas.
Collective effective dose – It is the quantity obtained by multiplying the average effective dose by the number of people exposed to a given source of ionizing radiation. Its unit is man-sievert.
Collet – It is a split sleeve used to hold work or tools during machining or grinding.
Collimate – It is to make parallel to a certain line or direction.
Collimation – It is the operation of controlling a beam of radiation so that its rays are as nearly parallel as possible.
Collision efficiency – It is the cross-sectional area of undisturbed fluid containing particles which ultimately impinges on a given solid surface, divided by the projected area of the solid surface.
Collodion replica – In metallography, it is a replica of a surface cast in nitro-cellulose.
Colloid – It is a finely divided organic substance which tends to inhibit the formation of dense scale and results in the deposition of sludge, or causes it to remain in suspension, so that it can be blown from the boiler.
Colloidal particle – It is an electrically charged particle, normally smaller in size than 200 micrometers, dispersed in a second continuous phase.
Colonial finish – It is a surface finish achieved by selectively buffing an oxidized surface, hence producing lustrous highlights against the oxidized background.
Colonies – These are regions within prior-beta grains with alpha platelets having nearly identical orientations. In commercially pure titanium, colonies frequently have serrated boundaries. Colonies arise as transformation products during cooling from beta field at cooling rates which induce platelet
nucleation and growth.
Colour anodizing – In anodizing of aluminum, it is formation of a coloured coating on aluminum where the coloured compound, pigment, or dye is incorporated after the coating has been formed and prior to sealing.
Colour buffing – It consists of producing a final high lustre by buffing.
Colour centre – It is a point lattice defect which produces optical absorption bands in an otherwise transparent crystal.
Coloured cement – It is prepared by adding special types of pigments to the portland cement. The pigments added to the white cement (2 % to 10 % of the cement) when needed to get light colors, while it is added to ordinary portland cement when needed to get dark colors. The cement and the pigment are grinded together.
Colour etching – It consists of immersing metallographic samples in specially formulated chemical etchants in order to produce a stable film on the sample surface. When viewed under an optical microscope, these surface films produce colours which correspond to the different phases in the alloy.
Colour filter – It is a device which transmits principally a predetermined range of wave-lengths. .
Colouring – It consists of producing desired colours on metal surfaces by appropriate chemical or electro-chemical reaction. It is the finishing process, or combination of processes, which alters the appearance of a surface through coating, chemical, and / or mechanical operations.
Colour oxide – It is a material used to impart colour to a porcelain enamel.
Colour temperature – It is the temperature in degrees Kelvin at which a black-body is to be operated for providing a colour equivalent to that of the source in question.
Column – Column is defined as vertical load-bearing member supporting axial compressive loads chiefly. This structural member is used to transmit the load of the structure to the foundation. In reinforced concrete buildings beams, floors, and columns are cast monolithically.
Column flotation – It is a milling process, carried out in a tall cylindrical column, whereby valuable minerals are separated from gangue minerals based on their wettability properties.
Column layout – Column layout reinforces the design and pattern of the columns of the whole structure. This plan is divided floor-wise and demarcates the exact size and distance between every column of the building. Column layout drawings further make it easier for the site engineers to make sense of the whole building layout.
Columnar structure – It is a coarse structure of parallel elongated grains formed by unidirectional growth, very frequently observed in castings, but sometimes seen in structures resulting from diffusional growth accompanied by a solid-state transformation.
Coma – It is a lens aberration occurring in the part of the image field which is some distance from the principal axis of the system. It results from different magnification in the different lens zones. Extra-axial object points appear as short, comet-like images, with the brighter small head toward the centre of the field (positive coma) or away from the centre (negative coma).
Combination dies – These are die-casting dies having two or more different cavities for different castings. The combination die can also be for forming.
Combination mill – It is an arrangement of a continuous mill for roughing and a guide mill or looping mill for shaping.
Combined blowing process – In the combined steel making process, oxygen needed to refine the steel is blown through the top mounted lance while the inert gas (nitrogen or argon) needed for the bottom stirring process is introduced into the melt through bottom stirring bricks for improving the process conditions by optimized mixing. The flow rate and type of stirring gas depends on the process phase and steel grade. A faster and better approaching of the metal slag equilibrium is achieved because of the bottom stirring. Equilibrium and mixing time depend on type, number, location of stirrers, and flow rate.
Combined carbon – It is the carbon in iron or steel which is combined chemically with other elements. It is not in the free state as graphite or temper carbon. It is the difference between the total carbon and the graphite carbon analyses.
Combined cyanide – It is the cyanide of a metal-cyanide complex ion.
Combined cycle gas turbine – In combined cycle gas turbine plant, a gas turbine generator generates electricity and the waste heat is used to make steam to generate additional electricity through a steam turbine. This last step improves the efficiency of electricity generation.
Combined patterns type wire rope construction – It has strand which is formed in a single operation using two or more of the above constructions. As an example, the wire rope can have a Seale construction in its first two layers and a Warrington construction in the third layer, and a Seale construction in the outer layer. The combined pattern type of wire rope construction is very superior in its fatigue resistance nature. It also has high flexibility and is superior in its wear resistance and hence has a wide range of uses.
Combined stacker and reclaimer – Combined stacker and reclaimer also known as stacker cum reclaimer can stack the material to form the stockpile or reclaim the stockpiled material and feed onto the main line conveyor. The stacker is mounted on the centre column, which allows rotation in both directions simultaneously with the vertical movement of the boom. Its height above the crest of the pile is kept at a minimum to reduce dust emission. Reclaiming takes place at the natural angle of slide. A raking harrow is mounted on the bridge reclaimer.
Combined stresses – These are those state of stresses which cannot be represented by a single component of stress, i.e., one that is these are more complicated than simple tension, compression, or shear.
Combustible loss – It is the loss representing the unliberated thermal energy occasioned by failure to oxidize completely some of the combustible matter in the fuel.
Combustibles – It is the heat producing constituents of a fuel.
Combustion – It is a high-temperature exothermic redox chemical reaction between a fuel and an oxidant, normally atmospheric oxygen, which produces oxidized, frequently gaseous products, in a mixture termed as smoke.
Combustion air – It is the air used in the combustion process. Air contains oxygen which is needed to combust fuel.
Combustion analysis – It is an analytical technique for determining the concentration of carbon and sulphur in samples. The sample is burned in a graphite crucible in the presence of oxygen, which causes carbon and sulphur to leave the sample as carbon dioxide and sulphur dioxide. These gases are then detected by infrared or thermal conductive means.
Combustion chamber – A combustion chamber is the area within where the fuel / air mix is ignited.
Combustion efficiency – It is the effectiveness of the burner to completely burn the fuel. A well-designed burner operates with as little as 10 % to 20 % excess air, while converting all combustibles in the fuel to useful energy.
Combustion gases – Combustion gases are the hot gaseous products from the fire. These are also called ‘flue gases’ or ‘exhaust-gases’.
Combustion gas pass – One pass is the travel of the combustion gases once along the length of the boiler. If the gases are reversed and passed through another source of the boiler, this is a second pass.
Combustion head – It is the part of the burner which mixes the combustion supporting air with the fuel and stabilizes the flame which is generated. The components of the combustion head essentially are (i) the fuel metering device consisting of nozzles for liquid fuels and orifices and distributors for gaseous Fuels, (ii) the turbulator diffuser disk, which mixes the fuel and the combustion air, and stabilizes the flame to avoid it blowing back into the burner, (iii) the flame ignition system which uses electric arcs produced by high-voltage powered electrodes directly igniting the flame or coupled with a pilot burner, (iv) a flame sensor for motoring the flame, and (v) the flame tube made of profiled metal cylinder which defines the output speed range.
Combustion rate – It is the burning rate of the fuel, which measures how fast the fuel burns in terms of mass per hour/minute. Coals with higher volatile matter has improved combustion rate.
Comet tails – These are a group of comparatively deep unidirectional scratches which form adjacent to a micro-structural discontinuity during mechanical polishing. They have the general shape of a comet tail. Comet tails form only when a unidirectional motion is maintained between the surface being polished and the polishing cloth.
Comminution – It is the breaking up or grinding an ore into small fragments. It also consists of reducing metal to powder by mechanical means. It is also the act of process of reduction of powder particle size, normally but not necessarily by grinding or milling.
Commissioning – It is the process of bringing new plant into operation.
Common cause of failure (CCF) – It is a dependent failure (quod vide, q.v.) of two or more (redundant) system elements due to a single cause, for example a fire or a flood.
Common causes – These are the causes which are normally present in a process giving rise to variations within limits.
Common mode of failure (CMF) – It is a dependent failure (q.v.) where two or more system elements fail in the same manner, for example by having the same incorrect maintenance action performed on all the elements.
Communication – It is the process of sharing ideas, information, and messages with others in a particular time and place. It includes writing and talking, as well as non-verbal communication (such as facial expressions, body language, or gestures), visual communication (the use of images or pictures, such as painting, photography, video or film), and electronic communication (telephone calls, electronic mail, cable television, or satellite broadcasts).
Compact – It is the object produced by the compression of metal powder, normally while confined in a die. It is also the operation or process of producing a compact, which is sometimes called pressing.
Compacted graphite iron – It is the cast iron having a graphite shape intermediate between the flake form typical of gray cast iron and the spherical form of fully spherulitic ductile cast iron. An acceptable compacted graphite iron structure is one which contains no flake graphite, less than 20 % spheroidal graphite, and 80 % compacted graphite It is also known as CG iron or vermicular iron. Compacted graphite cast iron is produced in a manner similar to that for ductile cast iron, but using a technique which inhibits the formation of fully spherulitic graphite nodules.
Compacting pressure – In powder metallurgy, it is the specific compacting force related to the area of contact with the press punch expressed in mega-pascals, or mega-newtons per square meter.
Compaction – It is the act of forcing particulate or granular material together (consolidation) under pressure or impact to yield a relatively dense mass or formed object. In powder metallurgy, It is the preparation of a compact or object produced by the compression of a powder, normally while confined in a die, with or without the inclusion of lubricants, binders, and so forth. Compaction can be done with or without the concurrent applications of heat.
Comparison standard – It is a standard micrograph or a series of micrographs, normally taken at 75x to 100× magnifications. It is used to determine grain size by direct comparison with the image.
Compatibility standards – These are used to ensure that different parts or products fit together e.g. a plug fitting into a socket, nuts and bolts matching the thread etc. These are typically standards specifying requirements for size and design.
Compatibility – It is the ability of entities to be used together under specific conditions to fulfill relevant requirements.
Compatibility (frictional) – In tribology, the materials which show good sliding behaviour, including resistance to adhesive wear, are termed frictionally compatible. However, it is to be noted that under some conditions materials which are not normally considered compatible in the metallurgical sense (e.g., silver and iron) can be very compatible in the frictional sense.
Compatibility (lubricant) – In tribology, it is a measure of the degree to which lubricants or lubricant components can be mixed without harmful effects such as formation of deposits.
Compatibility (metallurgical) – It is a measure of the extent to which materials are mutually soluble in the solid state.
Compensating eye-piece – It is an eye-piece designed for use with apochromatic objectives. They are also used to advantage with high-power (oil-immersion) achromatic objectives. Since apochromatic objectives are under-corrected chromatically, these eye-pieces are over-corrected. Hese eye-pieces are designed for use with objectives such as apochromats to correct chromatic aberration.
Compensation – In a hydrostatic bearing, it is the use of flow resistances between the supply and the entry to the bearing.
Complete combustion – It is the complete oxidation of all the combustible constituents of a fuel.
Complete fusion – It is the fusion which has occurred over the entire base material surfaces intended for welding and between all layers and weld beads.
Complete joint penetration – It is also known as complete penetration. It is a penetration by weld metal for the full thickness of the base metal in a joint with a groove weld.
Completion drawing – This drawing is also known as record drawing or as-built drawing. There are bound to be certain variations, additions, or alterations as project progresses, because of unseen site conditions and advancement in technology. Howsoever small the variations, additions, or alterations can be, these are to be recorded on the completion drawings. Completion drawings are to be prepared simultaneously as the work proceeds.
Complexation – It is the formation of complex chemical species by the coordination of groups of atoms termed ligands to a central ion, commonly a metal ion. Generally, the ligand coordinates by providing a pair of electrons that forms an ionic or covalent bond to the central ion.
Complexing agent – It is a substance which is an electron donor and which combines with a metal ion to form a soluble complex ion.
Complex ion – It is an ion composed of two or more ions or radicals, both of which are capable or independent existence, for example, cupro-cyanide (Cu(CN)3)2-.
Complex ore – It is an ore containing a number of minerals of economic value. The term frequently implies that there are metallurgical difficulties in liberating and separating the valuable metals.
Complex phase steels – Complex phase (CP) steels typify the transition to steel with very high ultimate tensile strengths. The microstructure of complex phase steels contains small amounts of martensite, retained austenite and pearlite within the ferrite / bainite matrix. An extreme grain refinement is created by retarded recrystallization or precipitation of micro alloying elements like titanium or niobium. In comparison with dual phase (DP) steels, complex phase steels show significantly higher yield strengths at equal tensile strengths of 800 MPa and higher. Complex phase steels are characterized by high energy absorption and high residual deformation capacity.
Complex silicate inclusions – It is a general term describing silicate inclusions containing visible constituents in addition to the silicate matrix. An example is corundum or spinel crystals occurring in a silicate matrix in steel.
Component – It is one of the elements or compounds used to define a chemical (or alloy) system, including all phases, in terms of the fewest substances possible. It is also one of the individual parts of a vector as referred to a system of coordinates. Also, it is an individual functional element in a physically independent body which cannot be further reduced or divided without destroying its stated function, for example, a resistor, capacitor, diode, or transistor.
Component drawing – A component drawing is mostly referred to as the drawing supplied by the manufacturer of the equipment. This kind of the drawing is complete with all the details of the component hence providing a detailed insight into its markings and different sub-parts. The component drawing provides detailed information about the nature and manufacture of a specific item incorporated on an assembly / layout drawing. It is a detailed drawing of a component for facilitating its production. All the principles of orthographic projection and the technique of graphic representation are followed to communicate the details in this drawing.
Composite – It is a sample composed of two or more increments.
Composite bearing material – It is a solid material composed of a continuous or particulate solid lubricant dispersed throughout a load-bearing matrix to provide continuous replenishment of solid lubricant films as wear occurs, and effective heat transfer from the friction surface. However, it is to be noted that composite bearing materials need not only be self-lubricating, but can also be used for low wear, good frictional heat dissipation, or controlled frictional response (e.g., brake materials). Examples of composite materials are metal-matrix composites, laminated composites, filament-wound composites, and fiber-mineral-metal-filled composites.
Composite coating – It is a coating on a metal or non-metal which consists of two or more components, one of which is frequently particulate in form. Example is a cermet composite coating on a cemented carbide cutting tool. It is also known as multilayer coating.
Composite electrode – It is a welding electrode made from two or more distinct components, at least one of which is filler metal. A composite electrode can exist in any of different physical forms, such as stranded wires, filled tubes, or covered wire.
Composite joint – It is a joint in which welding is used in conjunction with mechanical joining.
Composite material – It is a combination of two or more materials (reinforcing elements, fillers, and composite matrix binder), differing in form or composition on a macroscale. The constituents retain their identities, that is, they do not dissolve or merge completely into one another although they act in concert. Normally, the components can be physically identified and show an interface between one another. Examples are cermets and metal-matrix composites.
Composite plate – It is an electrodeposit consisting of layers of at least two different compositions.
Composite powder – It is a powder in which each particle consists of two or more different materials.
Composite products – These products consist of (i) plate, sheet and strip clad with steels or alloys in order to resist wear, chemical corrosion or heat distortion with bonding which is normally achieved by rolling, and sometimes by spraying, welding or explosion, (ii) sandwich steel sheet formed from two sheets bonded together by means of a synthetic sound-insulating plastic layer, and (iii) sandwich panels fabricated from two ribbed sheets bonded by an insulating layer.
Composites – These are engineered or naturally occurring materials made from two or more constituent materials with significantly different physical or chemical properties that remain separate and distinct at the macroscopic scale within the finished structure.
Composite structure – It is a structural member (such as a panel, plate, pipe, or other shape) which is built up by bonding together two or more distinct components, each of which can be made of a metal, alloy, non-metal, or composite material. Examples of composite structures include honeycomb panels, clad plate, electrical contacts, sleeve bearings, carbide-tipped drills or lathe tools, and weldments constructed of two or more different alloys.
Composition – It specifies the identity, arrangement, and ratio of the chemical elements making up a compound by way of chemical and atomic bonds. Chemical formulas can be used to describe the relative quantities of elements present in a compound.
Compositional depth profile – It is the atomic concentration measured as a function of the perpendicular distance from the surface.
Compound compact – It is a powder metallurgy compact consisting of mixed metals, the particles of which are joined by pressing or sintering, or both, with each metal particle retaining substantially its original composition.
Compound die – It is a die which is designed to perform more than one operation on a part with one stroke of the press, such as blanking and piercing, in which all functions are performed simultaneously within the confines of the blank size being worked.
Compound zone – It is the surface layer of diffusion-treated steels, which is made up of inter-metallic compounds such as nitrides or carbides.
Compressed air – It is the air which is kept under a pressure having a value greater than the atmospheric pressure (1.03 kg/sq cm). It is a medium that carries potential energy. It is a widely used utility in a steel plant. It is an important source of instrument air. Other than instrumentation air which is completely dry and free from contaminants, there are the three main uses of compressed air in a steel plant namely (i) blast air for blast furnace, (ii) for the production of oxygen, nitrogen and argon in an air separation plant, and (iii) a utility gas with several uses. Major among these is the operation of pneumatic devices.
Compressibility – Compressibility is the measure of how much a given volume changes instantaneously when placed under pressure. In better words, it is defined as a measure of the relative volume change of a fluid or solid as a response to a pressure change. Hence, if the pressure is increased then the volume decreases considerably. In powder metallurgy, it is the ability of a powder to be formed into a compact having well-defined contours and structural stability at a given temperature and pressure. It is a measure of the plasticity of powder particles. It is also a density ratio determined under definite testing conditions. It is also referred to as compactibility.
Compressibility number – It is a dimensionless group used in gas bearing calculations. It is to be noted that for thrust bearings, the compressibility number relates viscosity, velocity, pressure, and clearance. · For journal bearings, the compressibility number relates to viscosity, rotational speed, pressure, radius, and clearance.
Compression – It is the application of balanced inward (pushing) forces to different points on a material or structure, that is, forces with no net sum or torque directed so as to reduce its size in one or more directions.
Compression modulus – The compression modulus measures the stiffness of the material or the ability of the material to withstand changes in length when subjected to compressive loads. The higher the compression modulus, the stiffer the material.
Compression ratio – In powder metallurgy, it is the ratio of the volume of the loose powder to the volume of the compact made from it.
Compression set – In seals, it is the difference between the thickness of a gasket of static seal before the seal is compressed and after it is released from compression. Compression set is normally expressed as a percentage of the total compression.
Compression springs – These springs are designed to operate with a compression load and hence the spring becomes shorter as the load is applied to it.
Compression test – It is a method for assessing the ability of a material to withstand compressive loads.
Compressive – It is pertaining to forces on a body or part of a body which tend to crush, or compress, the body.
Compressive burr – It is the burr produced in blanking or piercing operations in which the slug separates from the stock in a compressive stress field. Burrs produced in this manner initially begin as tensile burrs and are typically identified as tensile-plus-compressive burrs.
Compressive modulus – It is the ratio of compressive stress to compressive strain below the proportional limit. Theoretically it is equal to Young’s modulus determined from tensile experiments.
Compressive strength – It is the maximum compressive stress which a material is capable of developing, based on original area of cross section. If a material fails in compression by a shattering fracture, the compressive strength has a very definite value. If a material does not fail in compression by a shattering fracture, the value got for compressive strength is an arbitrary value depending on the degree of distortion which is regarded as indicating complete failure of the material.
Compressive stress – It is a stress which causes an elastic body to deform (shorten) in the direction of the applied load.
Compressometer – It is an Instrument for measuring change in length over a given gauge length caused by application or removal of a force. It is normally used in compression testing of metal specimens.
Computer – It is a machine which can be programmed to automatically carry out sequences of arithmetic or logical operations. Modern digital electronic computers can perform generic sets of operations known as programs. These programs enable computers to perform a wide range of tasks.
Computer aided design – Computer-aided design (CAD) is a way to digitally create 2-D drawings and 3-D models of real-world products before they are manufactured. With 3-D computer aided design, a person can share, review, simulate, and modify designs easily, opening doors to innovative and differentiated products.
Computer-aided engineering – Computer-aided engineering (CAE) is the use of computer software across industries to simulate product performance to improve designs or assist in the resolution of engineering problems. This includes simulation, validation and optimization of products, processes and manufacturing tools.
Computer aided manufacturing – Computer-aided manufacturing (CAM) is also known as computer-aided modeling or computer-aided machining. It is the use of software to control machine tools in the manufacturing of the work-pieces, and to automate the manufacturing process. It is the software which tells a machine how to make a product by generating toolpaths.
Computerized maintenance management system (CMMS) – It provides such support. It is also called computer managed maintenance system, or computerized asset management systems (CAMS). It is computer software programmes designed to assist in the planning, management, and administrative control needed for effective maintenance. The output of these programmes can involve writing, planning, and recording work accomplished, collecting a history of work accomplished, recording shipping and receiving transactions, and generating reports.
Computer monitor – It is an output device that displays information in pictorial or textual form. A discrete monitor comprises a visual display, support electronics, power supply, housing, electrical connectors, and external user controls.
Computer numerical control (CNC) – It is the automated control of the machine tools by means of a computer. It is used to operate machine tools such as drills, lathes, mills, grinders, and roll turning and roll grinding machines. Computer numerical control machine tools transform a piece of material into a specified shape by following coded programmed instructions and without a manual operator directly controlling the machining operation.
Computer program drawing – It describes the design details, establishes item identification, and provides for control of the software it represents. Three types of drawings are generally used. These are (i) computer program listing drawing, (ii) computer program assembly drawing, and (iii) computer program set drawing. Computer program listing drawing is prepared to document operational computer programs / software. It provides design details and establishes item identification for the computer program. It identifies the master source code, object code, or both, for the computer program in human readable form. The drawing specifies the media materials, marking requirements, and the applicable specifications. The type of software tools (computer, assembler, and compiler etc.) required to produce the object code from the source code is also specified. The computer program assembly drawing contains computer generated load maps of computer programs with multiple components / subprograms. It lists each subprogram and specifies the media materials, type of equipment required to produce the computer program, marking requirements, and applicable specifications. It establishes item identification for the assembly process. The computer program set drawing groups two or more individual computer programs into a set for handling convenience. It consists of a parts list which identifies the computer programs and applicable notes. It establishes item identification for the set.
Compton scattering – It is the elastic scattering of photons by electrons.
CONARC process – The basic concept of CONARC process is to carry out decarburization in one furnace shell and electric melting in another furnace. The process starts with the oxygen-blowing stage, which is followed by the electric arcing stage. The whole process operates in sequences inter-changeable in both furnace shells, starting with hot metal charging, then the oxygen lance is put into operation and start of the blowing. At the end of the blowing stage, solid charge materials like scrap and / or direct reduced iron are charged into the furnace shell, the electrodes are swung in the operating position and arcing starts. At the end of arcing, deslagging takes place. Finally, the liquid steel is tapped into the ladle.
Concave grating – It is a diffraction grating on a concave mirror surface.
Concavity – It is curved as the inner surface of a sphere. It is the maximum distance from the face of a concave fillet weld perpendicular to a line joining the weld toes.
Concentrate – It is a fine, powdery product of the milling process containing a high percentage of valuable metal. Concentrates are the product of ore dressing operations whereby valuable metals recovered through mining operations are separated from waste rock.
Concentration – It is the mass of a substance contained in a unit volume of sample, for example, grams per litre. It is also a process for enrichment of an ore in valuable mineral content by separation and removal of waste material, or gangue. In boiler, it is the weight of solids contained in a unit weight of boiler or feed water. It is also the number of times which the dissolved solids have increased from the original quantity in the feed-water to that in the boiler water because of evaporation in generating steam.
Concentration cell It is an electrolytic cell, the electromotive force of which is caused by a difference in concentration of some component in the electrolyte. This difference leads to the formation of discrete cathode and anode regions.
Concentration polarization – It is that portion of the polarization of a cell produced by concentration changes resulting from passage of current through the electrolyte.
Concentrator – It is a milling plant which produces a concentrate of the valuable minerals or metals. Further treatment is needed to recover the pure metal.
Concentricity – It is conformance to a common centre as, for example, the inner and outer walls of round tube.
Concept drawing or sketch – Concept drawing or sketch is a drawing, frequently freehand, which is used as a quick and simple way of exploring initial ideas for designs. This drawing /sketch is not intended to be accurate or definitive, merely a way of investigating and communicating design principles and aesthetic concepts. Concept drawings are more like the first draft of a construction project which is made in the first instance. They are not very detailed or distinguished. These drawings are like rough sketches. They are more prominently used to describe an overview of the object.
Concrete – It is a composite building material made from a mixture of sand, gravel, crushed rock, or other aggregates (coarse and fine) held together in a stone like mass with a binder such as cement and water. The stone like mass is formed due to the hydration of cement and eventually due to its hardening. Sometimes one or more admixtures (plasticizers, super plasticizers, accelerators, retarders, Pozzolanic materials, air entertaining agents, fibers, polymers and silica furies) are added to change certain characteristics of the concrete such as its workability, durability, and time of hardening. Hardened concrete has a high compressive strength and a very low tensile strength.
Concurrent heating – It is the application of supplemental heat to a structure during a welding or cutting operation.
Condensate – It is the liquid phase produced by the condensation of steam. It is the condensed water resulting from the removal of latent heat from steam.
Condensation – It is defined as the change in the physical state of water vapour to liquid water. It is reverse of vapourization.
Condensation stain – It is the superficial oxidation of the surface with a water film, in the absence of circulating air, held between closely adjacent metal surfaces.
Condenser – It is an equipment which used to cool exhaust steam from a turbine below the boiling point so that it can be returned to the heat source as water. It is also a system of lenses or mirrors designed to collect, control, and concentrate light.
Condenser aperture – In electron microscopy, it is an opening in the condenser lens controlling the number of electrons entering the lens and the angular aperture of the illuminating beam.
Condenser lens – It is a device which is used to focus radiation in or near the plane of the object.
Condenser tube – The term ‘heat-exchanger tube’ is preferred, unless specific reference to a condenser application is intended.
Condition based maintenance – It is a set of maintenance actions based on the real-time or near real-time assessment of equipment conditions, which is achieved from embedded sensors and / or external tests and measurements, taken by portable equipment and / or subjective condition monitoring.
Conditioning – It is the removal of surface defects (seams, laps, pits, etc.) from steel. It is normally done when the steel is in semifinished condition (bloom, billet, slab). It can be accomplished after an inspection by chipping, scarfing, grinding, or machining.
Conditioning facility – It is a facility which exists for the purpose of changing the chemical or physical form of a material to make it suitable for a specific purpose. It is also applied in waste management to a facility for processing waste to condition it for storage, transport and disposal.
Conditioning heat treatment – It is a preliminary heat treatment used to prepare a material for a desired reaction to a subsequent heat treatment. For the term to be meaningful, the exact heat treatment is to be specified.
Conditions for acceptance (CFA) – These are the requirements of a receiving body in relation to the parameters with which the material is to comply in order for the material to be accepted into the receiving body’s facility.
Conductance – It is the capacity of a medium, normally expressed in mhos, for transmitting electric current. It is the reciprocal of resistance.
Conducting salt – It is a salt added to the solution in order to increase its conductivity.
Conduction – It is the transmission of heat through and by means of matter unaccompanied by any obvious motion of the matter. The transfer of heat through matter (i.e., solids, liquids, or gases) is without bulk motion of the matter. In another ward, conduction is the transfer of energy from the more energetic to less energetic particles of a substance due to interaction between the particles.
Conductivity – It is the property of a water sample to transmit electric current under a set of standard conditions. It is normally expressed as micro-ohms conductance. It is a measure of the ability of water to pass an electrical current. Since dissolved salts and other inorganic chemicals conduct electrical current, conductivity increases as salinity increases. Conductivity is a material property relating heat flux (heat transferred per unit area per unit time) to a temperature difference.
Conduit – A conduit is a small tunnel, pipe, or channel through which water or electrical wires go. Conduit is used for protecting and routing electrical wiring in a building or structure.
Conduit, rigid – It is the conduit having dimensions of nominal size 40 pipe in standardized length with threaded ends.
Conduit pipe – It is welded or seamless pipe intended especially for fabrication into rigid conduit, a product used for the protection of electrical wiring systems. Conduit pipe is not subjected to hydrostatic testing unless so specified. It can be black or galvanized, as specified. It is furnished in standard weight pipe sizes from 6 mm to 150 mm in lengths of around 3 m to 6 m, with plain ends or threaded ends, as specified.
Cone – It is the conical part of an oxy-fuel gas flame next to the orifice of the tip.
Cone angle – It is the angle which the cutter axis makes with the direction along which the blades are moved for adjustment, as in adjustable-blade reamers where the base of the blade slides on a conical surface.
Cone classifier – It is simply a cone / conical vessel installed point down. It consists of a discharge launder around the top. The feed is introduced in the form of a suspension through a feed inlet provided at the centre at the top. The coarse particles get collected at the point of the cone while the fine fraction along with the liquid is removed from launder as overflow. Cone classifiers are normally used in ore dressing plants.
Cone crusher – Cone crusher is consisting of a crushing chamber, a crushing cone and an operating mechanism. The cone is built in to a vertical shaft, which is supported from the top with a bowl-shaped bearing and from the other end to an eccentric operating mechanism.
Coned-out coil – It is lateral stacking, mainly in one direction, of wraps in a coil so that the edges of the coil are conical rather than flat. Improper alignment of rolls over which the metal passes before rewinding is a typical cause.
Cone resistance value – It is a measure of the yield stress of a grease, obtained by static indentation with a cone. It is to be noted that the equilibrium depth of penetration is measured, not the penetration in a given time, which is the penetration value.
Cone shell method – It is the simplest of the stacking methods. In the cone shell method, the pile is formed by depositing material in a single cone from a fixed position. When this conical pile is full, the stacker moves to a new position and a new cone is formed against the shell of the first one. This process continues in the longitudinal direction of the storage pile until the stockpile is complete.
Confidence interval – It is that range of values, calculated from estimates of the mean and standard deviation, which is expected to include the population mean with a stated level of confidence. Confidence intervals in the same context also can be calculated for standard deviations, lines, slopes, and points.
Confined space – It is an area which is not designed for continuous human occupancy and has limited opening for entry, exit, and ventilation.
Confinement – It is the process of preventing the release of radioactive substances to the environment during operation or following an accident.
Conformability – In tribology, it is that quality of a plain bearing material which allows it to adjust itself to shaft deflections and minor misalignments by deformation or by wearing away of bearing material
without producing operating difficulties.
Conformal coating – It is a coating which covers and exactly fits the shape of the coated object.
Conformal surfaces – These are the surfaces whose centres of curvature are on the same side of the interface. In wear testing, it refers to the case where the curvature of both samples matches such that the nominal contact area during the testing remains approximately constant.
Conformity – It is the fulfillment of specified requirements.
Conglomerate – It is a sedimentary rock consisting of rounded, water-worn pebbles or boulders cemented into a solid mass.
Congruent melting – It is an isothermal or isobaric melting in which both the solid and liquid phases have the same composition throughout the transformation.
Congruent point – The congruent point on a phase diagram is where different phases of same composition are in equilibrium.
Congruent transformation – It is an isothermal or isobaric phase change in metals in which both of the phases concerned have the same composition throughout the process.
Conjugate phases – In microstructural analysis, these are those states of matter of unique composition which coexist at equilibrium at a single point in temperature and pressure. For example, the two coexisting phases of a two-phase equilibrium.
Conjugate planes – These are the two planes of an optical system such that one is the image of the other.
Connection diagram – It is also known as wiring diagram. It depicts the general physical arrangement of electrical connections and wires between circuit elements in an installation or assembly. It shows internal connections, but may include external connections which have one termination inside and one outside the assembly. It contains the details necessary to make or trace connections involved. It is prepared to show the connection of wires and circuit elements at any level of assembly or installation. It includes (i) physical relationship of circuit elements and their connections, (ii) items identified by reference designations, (iii) clearly identified terminal arrangements, (iv) wires numbered for reference, and (v) wire and termination descriptions.
Conservator system – A conservator is connected by piping to the main transformer tank which is completely filled with oil. The conservator also is filled with oil and contains an expandable bladder or diaphragm between the oil and air to prevent air from contacting the oil. Air enters and exits the space above the bladder / diaphragm as the oil level in the main tank goes up and down with temperature. Air typically enters and exits through a desiccant-type air dryer which is to have the desiccant replaced periodically. The main parts of the system are the expansion tank, bladder or diaphragm, breather, vent valves, liquid-level gauge and alarm switch. Vent valves are used to vent air from the system when filling the unit with the oil. A liquid-level gauge indicates the need for adding or removing transformer oil to maintain the proper oil level and permit flexing of the diaphragm.
Consignee – It is a person, or organization which receives a consignment.
Consignor – It is a person, or organization which prepares a consignment for transport.
Consistency – it is an imprecise measure of the degree to which a grease resists deformation under the application of a force.
Constant life fatigue diagram – In failure analysis, it is a graph (normally on rectangular coordinates) of a family of curves, each of which is for a single fatigue life (number of cycles), relating alternating stress, maximum stress, minimum stress, and mean stress. The constant life fatigue diagram is normally derived from a family of S-N curves, each of which represents a different stress ratio for a 50 % probability of survival.
Constant spring – In this type of spring, the supported load remains the same throughout deflection cycle.
Consteel electric arc furnace process – In the electric arc furnace with the Consteel process, the adopted plant solution is the continuous feeding of electric arc furnace by the scrap, pre-heated and conveyed through a conveyor moving in a pre-heating tunnel, in which the exhaust gas from electric arc furnace, flowing counter current of metallic charge is combusted by injected air. The continuous feeding and preheating of scrap offer some potential advantages compared to the conventional electric arc furnace batch feeding.
Constituent It is one of the ingredients which make up a chemical system. It is also a phase or a combination of phases which occurs in a characteristic configuration in an alloy micro-structure.
Constitution diagram – It is also known as phase diagram. It is a graphical representation of the temperature and composition limits of phase fields in an alloy or ceramic system as they actually exist under the specific conditions of heating or cooling. A constitution diagram can be an equilibrium diagram, an approximation to an equilibrium diagram, or a representation of metastable conditions or phases.
Constraint – It is a restriction which limits the transverse contraction normally associated with a longitudinal tension and that hence causes a secondary tension in the transverse direction. It is normally used in connection with welding.
Constricted arc (plasma arc welding and cutting) – It is a plasma arc column which is shaped by a constricting nozzle orifice.
Constriction resistance – In electrical contact theory, it is the resistance which arises from the constriction of current flow lines in order to pass through small areas of contact (a-spots) at the interface of two contacting bodies.
Construction drawing – This drawing is also known as the working drawing. It provides dimensioned, graphical information which can be used at the construction site for the construction work, or by suppliers to fabricate components of the works or to assemble or install components. Along with specifications and bills of quantities or schedules of work, it forms a part of the ‘production information’, which is prepared by designers and passed to the construction team to enable a project to be constructed. Construction drawing provides an insight into the development of a construction site. These drawings are made in different stages. Some plans are necessary to be made before the construction begins while others are made while the construction is under progress. Construction drawing provides an outlet for the engineers to convey their ideas and concepts regarding a project. It is a means of showing in a graphical form the shape, size and position of a building or equipment on a site, together with the composition of the materials used and the way the building or equipment is to be constructed or put together.
Consumables – These are materials which participate in or are needed for a manufacturing process, but do not form part of the end product. Items which are substantially or totally consumed during a manufacturing process are deemed to be consumables.
Consumable electrode – It is a general term for any arc welding electrode made chiefly of filler metal. Use of specific names such as covered electrode, bare electrode, flux cored electrode, and lightly coated electrode is preferred.
Consumable electrode remelting – It is a process for refining metals in which an electric current pass between an electrode made of the metal to be refined and an ingot of the refined metal, which is contained in a water-cooled mould. As a result of the passage of electric current, droplets of molten metal form on the electrode and fall to the ingot. The refining action occurs from contact with the atmosphere, vacuum, or slag through which the drop falls.
Consumable insert – it is pre-placed filler metal which is completely fused into the joint root and becomes part of the weld.
Consumable spares – These are regularly used items such as fasteners, seals, gaskets, and fuse etc. These are normally low value items.
Contact angle – In lubrication, it is the angle at which the surface of a liquid drop meets the surface of a solid on which it is placed. In a bearing it is the angle between a diametral plane perpendicular to a ball-bearing axis and a line drawn between points of tangency of the balls to the inner and outer rings.
Contact bearings – These bearings have mechanical contact between elements, and they include sliding, rolling, and flexural bearings. Mechanical contact means that stiffness normal to the direction of motion can be very high, but wear or fatigue can limit their life. Contact bearings are classified under two main categories namely (i) plain or sliding bearing and (ii) rolling bearing.
Contact corrosion – It is a term primarily used in Europe to describe galvanic corrosion between dissimilar metals.
Contact fatigue – It is the cracking and subsequent pitting of a surface subjected to alternating Hertzian stresses such as those produced under rolling contact or combined rolling and sliding. The phenomenon of contact fatigue is encountered very frequently in rolling-element bearings or in gears, where the surface stresses are high because of the concentrated loads and are repeated several times during normal operation.
Contacting ring seal – It is a type of circumferential seal which utilizes a ring spring-loaded radially against a shaft. The ring is either gapped or segmented, in order to have radial flexibility. The seal has overlapping joints for blocking leakage at the gaps. An axial spring load seats the ring against the wall of its containing cartridge.
Contact lubrication – It is a little-used term relating to the conditions of lubrication obtained with solid lubricant powders rubbed into a surface. This term is normally not to be used.
Contact plating – It is a metal plating process wherein the plating current is provided by galvanic action between the work metal and a second metal, without the use of an external source of current.
Contact potential – In corrosion technology, it is the potential difference at the junction of two dissimilar substances.
Contact resistance – In resistance welding, it is the resistance to the flow of electric current between two work-pieces or an electrode and a work-piece. It is also the electrical resistance between two contacting bodies, which is the sum of the constriction resistance and the film resistance.
Contact stress – It is the stress which results near the surfaces of two contacting solid bodies when they are placed against one another under a non-zero normal force. This term is not sufficiently precise since it does not indicate the type of stress, although common usage normally implies elastic or Hertz stress. Contact (Hertzian) stress is the pressure at a contact between two solid bodies calculated as per the Hertz’s equations for elastic deformation. The theoretical area of contact between two non-conforming surfaces is frequently quite small. The interaction between these surfaces is frequently described as either point or line contact. Common examples of point contact are mating helical gears, cams and crowned followers, ball bearings and their races, and train wheels and rails. If the mating parts can be considered semi-infinite and if material behaviour is linearly elastic, then the local stress state can be described by Hertzian theory, as long as the contacting surfaces can be modeled as quadratic functions of those spatial coordinates defining the surfaces. Even in the absence of friction, the resulting three-dimensional stress state is quite complex, and although the local stress state is compressive, that is, the principal stresses beneath the load are negative, large subsurface shear stresses, which can serve as crack initiation sites, exist beneath the load.
Contact tube – It is a device which transfers current to a continuous electrode.
Contact type instruments – In contact type instruments, the sensing element of the instrument contacts the control medium for the measurements. Example is mercury in the glass thermometer.
Container – It is the chamber into which an ingot or billet is inserted prior to extrusion. The container for backward extrusion of cups or cans is sometimes called a die.
Containment – It is the act, process, or means to keep the parameters within the prescribed limits.
Containment area – During the construction of a facility designed to house radioactive materials, a series of containment barriers is put up between the materials inside and the environment outside the facility during construction. This creates separate areas called ‘containment areas’.
Contaminant – It is an impurity or foreign substance present in a material or environment which affects one or more properties of the material.
Contaminated water – It is the water which gets contaminated with dissolved minerals and suspended solid particles after its use.
Contamination – Contamination is the presence of a constituent, impurity, or some other undesirable element that renders something unsuitable, unfit or harmful for physical body, natural environment, and workplace etc. In case of nucleal facility, it is the radioactive material which is deposited on the surface of or inside structures, areas, objects, or people.
Contingency planning – Contingency planning provides protection against the unforeseen threats. It covers failures of critical systems, equipment, automated processes, energy, communications, suppliers, personnel, and natural calamities. It consists of the actions taken by the organization to prepare the organization for an impending emergency.
Continuity bond – It is a metallic connection which provides electrical continuity between metals structures.
Continuity of coating – It is the degree to which a porcelain enamel or ceramic coating is free of defects, such as bare spots, boiling, blisters, or copper-heads, which can reduce its protective properties.
Continuous annealing – Continuous annealing of sheet involves the rapid passage of uncoiled sheet through heating and cooling equipment. During continuous annealing, uncoiled steel sheet is passed through a two-stage furnace for times on the order of a few minutes. The first stage heats the steel and accomplishes recrystallization, while the second stage heats at a lower temperature to overage the steel and remove carbon from the solution effectively. Without this step, the thin sheet cools very rapidly and retain carbon in solution. This carbon eventually causes strain or quench aging and reduces sheet formability. The rapid cooling and in-line over-aging also enables the production of sheet steels for very demanding automotive and appliance applications. The metallurgical advantages of continuous annealing over conventional batch annealing include improved product uniformity, surface cleanliness and shape, and the versatility to produce a wide range of steel grades.
Continuous blow-down – It is the uninterrupted removal of concentrated boiler water from a boiler to control total solids concentration in the remaining water.
Continuous casting – It is a casting technique in which a cast shape is continuously withdrawn through the bottom of the mould as it solidifies, so that its length is not determined by mould dimensions. It is used mainly to produce semi-finished products such as billets, blooms, ingots, slabs, and strip.
Continuous casting machine – It is the machine in which continuous casting process is carried out. It links steelmaking with hot rolling of steel. In this machine, the liquid steel is solidified into a semi-finished steel product for subsequent rolling in the hot rolling mill. The basic operation of the machine is to convert liquid steel of a given composition into a strand of desired shape and size through a group of operations. Continuous casting machines are identified by the shape of the product they cast. Accordingly, these machines can be a billet casting machine, a bloom casting machine, a near net shape, beam blank, or dog bone casting machine, a round casting machine, a slab casting machine, a thin slab casting machine, or a strip casting machine.
Continuous casting mould – It is basically an open-ended box structure containing a water-cooled inner lining fabricated from a high purity copper alloy. The box can come in many shapes and sizes in order to cast different semis such as blooms, billets, round beam blanks, slabs, and thin slabs. Continuous casting mould is regarded as the heart of the continuous casting process and plays a very important role in the efficiency of the process and the strand quality. It is in the mould that the final cast shape and the strand surface quality are produced. If the conditions are not correct in the mould, then the strand quality cannot be corrected later. Once in the mould, the liquid steel freezes against the walls of the water-cooled copper mould to form a solid shell.
Continuous casting mould powders – These powders are used primarily to facilitate the passage of liquid steel through the mould of the continuous casting machine. It is also known by several other names such as mould powder, casting powder, mould flux, mould flux slag, or mould flux powder. Mould powder plays an important role in the continuous casting of liquid steel and is one of the most influential and critical factors in the stability of the casting process and for the smooth casting of the liquid steel.
Continuous cooling transformation (CCT) diagram – It is a set of curves drawn using logarithmic time and linear temperature as coordinates, which define, for each cooling curve of an alloy, the beginning and end of the transformation of the initial phase.
Continuous discharge elevators – In these elevators, V-type buckets are used without any gap between them. These elevators are employed for handling larger lumps and materials which can be difficult to handle by centrifugal discharge. The charging of the buckets is by direct filling. The discharge is by directed gravity i.e. when the buckets pass over head wheel, the flanged end of the preceding bucket act as a chute to deliver materials gently to the discharging spout. This type of charging and discharging is particularly effective for handling fragile materials. Both belt and chain are used as pulling medium. Speed is generally kept low. These elevators are used vertically or inclined. When inclined, special supports are provided for belt / chain in the return run, and wider casing is provided to allow for return run sag.
Continuous flight auger (CFA) piles – These piles are also referred to as auger-cast, auger-cast-in place, and auger-pressure grout piles. These piles are constructed by using continuous flight augers and by drilling to the final depth in one continuous process. When the drilling to the final depth is complete, the auger is gradually withdrawn as concrete or sand / cement grout is pumped into the hole through the hollow centre of the auger pipe to the base of the auger. Reinforcement, if needed, can be placed in these piles immediately after the withdrawal of the auger. The reinforcement is normally confined to the top 10 metres.
Continuous furnaces – These furnaces move the charged material while it is being heated. Material passes either over a stationary hearth, or the hearth itself moves. If the hearth is stationary, the material is pushed or pulled over skids or rolls, or is moved through the furnace by woven wire belts or mechanical pushers. Except for delays, a continuous furnace operates at a constant heat input rate, burners being rarely shut off. A constantly moving (or frequently moving) conveyor or hearth eliminates the need to cool and reheat the furnace (as is the case with a batch furnace), thus saving energy.
Continuous galvanizing – Sheet, wire, and tube sections are galvanized using a continuous process associated with the manufacturing of the product. The galvanized coating is almost 100 % pure zinc and applied to a maximum thickness of about 30 micrometers.
Continuous improvement process – It is a means by which the organization creates and sustains a culture of continuous improvement. The organization deliberately seeks to create a positive and dynamic working environment, foster teamwork, apply quantitative methods and analytical techniques, and tap the creativity and ingenuity of its employees.
Continuous phase – In an alloy or portion of an alloy containing more than one phase, it is the phase which forms the matrix in which the other phase or phases are dispersed.
Continuous precipitation – It is the precipitation from a super-saturated solid solution in which the precipitate particles grow by long range diffusion without recrystallization of the matrix. Continuous precipitates grow from nuclei distributed more or less uniformly throughout the matrix. They normally are randomly oriented, but can form a Widmanstatten structure. It is also called general precipitation.
Continuous rolling mill – It is a rolling mill consisting of a number of strands of synchronized rolls (in tandem) in which metal undergoes successive reductions as it passes through the different strands.
Continuous spectrum (x-rays) – It is the polychromatic radiation emitted by the target of an x-ray tube. It contains all wave lengths above a certain minimum value, which is known as the short wave-length limit.
Continuous-type furnace – It is a furnace used for heat treating materials which progress continuously through the furnace, entering one door and being discharged from another.
Continuous use temperature – It is the maximum temperature at which material can be subjected to continuous use without fear of premature thermal degradation.
Continuous weld – It is a weld extending continuously from one end of a joint to the other or, where the joint is essentially circular, completely around the joint.
Continuous welding process – In continuous (or furnace butt) welding process, skelp with square or slightly beveled edges is furnace heated to the welding temperature. The heated stock is roll formed into cylindrical shape as it emerges from the furnace. Additional heat is normally provided by an oxygen or air jet impinging on the seam edges, and the pipe passes through constricting rolls where the seam edges are welded by the pressure of the rolls.
Continuum – It is the non-characteristic rays emitted upon irradiation of a specimen and caused by deceleration of the incident electrons by interaction with the electrons and nuclei of the sample. It is also termed bremsstrahlung and white radiation.
Contour – It is that portion of the outline of a transverse cross section of an extruded shape which is represented by a curved line or curved lines.
Contour definition drawing – It contains the mathematical, numeric, or graphic definition required to locate and define a contoured surface. It does not establish item identification for the items described thereon. It is prepared to define complex surface geometry which cannot be conveniently included in the detail drawings of an item. It includes (i) mathematical equations for the geometric features, (ii) tabulated coordinates, (iii) graphic sections, and (iv) a summary of features and relationships to more basic coordinate systems in appropriate combinations to define the contoured surface or the desired points on a contoured surface.
Contour forming – It is also known as roll forming, stretch forming, tangent bending, and wiper forming.
Contour machining – It is the machining of irregular surfaces, such as those generated in tracer turning, tracer boring, and tracer milling.
Contour milling – It is the milling of irregular surfaces.
Contour roll forming – It is also known as roll forming or cold roll forming. It is a continuous process for forming metal from sheet, strip, or coiled stock into desired shapes of uniform cross section by feeding the stock through a series of roll stations equipped with contoured rolls (sometimes called roller dies). There are two or more rolls per station. Majority of the contour roll forming is done by working the stock progressively in two or more stations until the finished shape is produced.
Contract drawings – The engineer can carry on with detailed design only after the completion of tender drawings. If tendering has been straight forward and without any alternative proposals, the contract drawings are the same as tender drawings. If alternate proposals have been accepted, new or additional drawings are to be prepared as per the accepted tender proposals and alternatives.
Contraction – It is the volume change which occurs in metals and alloys upon solidification and cooling to room temperature. In galvanizing, it is the shrinkage of steel due to cooling after removal from the galvanizing pot.
Contrast enhancement (electron optics) – It is an improvement in electron image contrast by the use of an objective aperture diaphragm, shadow casting, or other means.
Contrast filter – It is a colour filter, normally with strong absorption, which uses the special absorption bands of the objective to control the contrast of the image by exaggerating or diminishing the brightness difference between differently coloured areas.
Contrast perception – It is the ability to differentiate different components of the object structure by different intensity levels in the image.
Control – It is a system for measuring and checking or inspecting a phenomenon. It suggests when to inspect, how frequently to inspect and how much to inspect. Control ascertains quality characteristics of an item, compares the same with prescribed quality characteristics of the item, compares the same with prescribed quality standards, and separates defective item from non-defective ones. For control a manual or automatic device is used for the regulation of a machine to keep it at normal operation. In case of automatic device, the device is motivated by variations in temperature, pressure, water level, time, light, or other influences.
Control and instrumentation – It comprises or contributes to some of all of the following namely automatic control of plant, alarms and indications, visualization of plant parameters, facilities to allow manual plant control, automatic protection systems, and engineered safety features.
Control chart – The control chart is a graph used to study how a process changes over time. Data are plotted in time order. A control chart always has a central line for the average, an upper line for the upper control limit, and a lower line for the lower control limit.
Control cooling conveyor – The controlled cooling conveyor system is one of the important parts of a wire rod mill for achieving the desired properties of the wire rods for a wide range of different steel grades. The optimum combination of speed, fan power, and cover position on the conveyor enables processing in a wide range of conditions, including both fast and slow cooling modes within a single system. This capability enables wire rod mills to produce a broad spectrum of plain carbon and alloy steels, as well as stainless steels and other specialty grades.
Control drawings – Control drawing is that drawing which is used for the control of certain activities. There are usually six categories of control drawings namely (i) procurement control drawing, (ii) vendor item drawing, (iii) source control drawing, (iv) design control drawing, (v) interface control drawing, and (vi) identification cross reference drawing.
Controlled area – It is an area outside a restricted zone but within the site boundary of a facility. Access to such an area can be limited for any reason.
Controlled atmosphere – It is a specified inert gas or mixture of gases at a pre-determined temperature in which selected processes take place. As applied to sintering of powders, it is to prevent oxidation and destruction of the powder compacts.
Controlled blasting – It is the blasting patterns and sequences designed to achieve a particular objective. Cast blasting, where the muck pile is cast in a particular direction, and deck blasting, where holes are loaded once but blasted in successive blasts days apart, are examples.
Controlled cooling – It consists of cooling a metal or alloy from a high temperature in a pre-determined manner to avoid hardening, cracking, or internal damage, or to produce desired micro-structure or mechanical properties.
Controlled etching – It is the electrolytic etching with selection of suitable etchant and voltage resulting in a balance between current and dissolved metal ions.
Controlled-potential coulometry – Substances determined by controlled-potential coulometry are electrolyzed in a portion of the sample solution using the methodology of controlled-potential electrolysis. A specially designed electrolysis cell and feedback controller called a potentiostat is used. The conditions for analytical coulometry are designed to electrolyze only the desired substance (among possibly several in a mixture) and to convert the substance rapidly and completely to a desired product. For example, electrolysis of a metal ion species can result in its transformation to a soluble species of another oxidation state or reduction to a metal deposit on the electrode, as in electroplating.
Controlled-pressure cycle – it is a forming cycle during which the hydraulic pressure in the forming cavity is controlled by an adjustable cam which is coordinated with the punch travel.
Controlled or measured variable – It is the monitored output variable from a process. The value of the monitored output parameter is normally held within tight given limits.
Controlled rolling – It is a hot-rolling process in which the temperature of the steel is closely controlled, particularly during the final rolling passes, to produce a fine-grain microstructure.
Controller – It is a device receiving a process variable (PV) signal from a primary sensing element (PSE) or transmitter, comparing that signal to the desired value (called the set point) for that process variable, and calculating an appropriate output signal value to be sent to a final control element (FCE) such as an electric motor or control valve.
Control limits – These are limits on control charts calculated on the basis of data collected under controlled conditions. Values outside these limits indicate the presence of an assignable cause and need for corrective action.
Controlling – It is the process whereby organization sets itself performance objectives and strives to achieve them as best it can over time.
Control panel – It is a flat, frequently vertical, area where control or monitoring instruments are displayed or it is an enclosed unit that is the part of a system which users can access, such as the control panel of a reheating furnace. It is also called control unit.
Control rods – These are the devices to absorb neutrons so that the chain reaction in a reactor core can be slowed or stopped by inserting them further, or accelerated by withdrawing them.
Control rolled steels – These steels are hot rolled as per predetermined rolling schedule designed to develop a highly deformed austenite structure which then transforms into a very fine equiaxed ferrite structure on cooling.
Control room – It is a room from where the operator operates the process or the equipment. The control room houses several displays for displaying the process parameters, control panels, as well as control and monitoring equipments and instruments.
Control system structure – It is an important step in process control design. The selection of control system structure is based on the type of control used for the process/plant. A centralized multi-input multi-output (MIMO) controller or a set of single-input single-output (SISO) controllers can be used to control a distributed or decentralized process. A decentralized type of control system is more common than the centralized control system in the process industry, as it has more captivating advantages such as it is easy to understand, it uses uncomplicated hardware, and it employs simple working algorithms. On the other hand, centralized type of control e.g., Model Predictive controllers (MPC), has several limitations such as higher maintenance cost, difficulties in operation, complicated structure, and lack of flexibility which can result in fragile controller. However, centralized controllers have the potential to operate systems at optimal levels, which can potentially have noticeable economic benefits.
Control unit – It is a component of a computer’s central processing unit which directs the operation of the processor. It typically uses a binary decoder to convert coded instructions into timing and control signals that direct the operation of the other units (memory, arithmetic logic unit and input and output devices, etc.).
Control valve – It is a valve which controls a process variable, such as pressure, flow or temperature, by modulating its opening in response to a signal from a controller.
Convection – It is the transmission of heat by the circulation of a liquid or gas. It can be natural, with the circulation caused by buoyancy affects because of temperature differences, or forced with circulation caused by a mechanical device such as a fan or pump.
Conventional forging – It is a forging characteristic by design complexity and tolerances which falls within the broad range of general forging practice.
Conventional milling – It is the milling in which the cutter moves in the direction opposite to the feed at the point of contact.
Conventional strain – It is the unit of change in the size or shape of a body because of force. The term is also used in a broader sense to denote a dimensionless number which characterizes the change in dimensions of an object during a deformation or flow process.
Conventional stress – It is the intensity of the internally distributed forces or components of forces which resist a change in the volume or shape of a material that is or has been subjected to external forces. Stress is expressed in force per unit area. Stress can be normal (tension or compression) or shear.
Convergent-beam electron diffraction (CBED) – it is a technique of impinging a highly convergent electron beam on a crystal to produce a diffraction pattern composed of disks of intensity. In addition to d-spacing and crystal orientation information, the technique can provide information on crystallographic point or space group symmetry.
Conversion coating – It is a coating consisting of a compound of the surface metal, produced by chemical or electro-chemical treatments of the metal. Examples include chromate coatings on zinc, cadmium, magnesium, and aluminum, and oxide and phosphate coatings on steel.
Converter – It is a furnace in which oxygen is blown through a bath of molten metal or matte, oxidizing the impurities and maintaining the temperature through the heat produced by the oxidation reaction. Typical converters are basic oxygen furnace and argon oxygen decarburization vessels.
Converter gas – It is also known as LD gas. It is a by-product gas produced during the production of liquid steel in a basic oxygen furnace (converter), where impurities of hot metal are oxidized with oxygen gas. The main constituents of converter gas are carbon mono-oxide, carbon di-oxide, oxygen, and nitrogen. Composition wise it is similar to blast furnace gas but with lesser percentage of nitrogen in it. Converter gas is a colourless, toxic, hazardous, and explosive gas.
Convexity – It is curved such as the outer surface of a sphere. In welding, it is the maximum distance from the face of a convex fillet weld perpendicular to a line joining the weld toes.
Conveyor belt – It has four components namely (i) carcass or carcase which consists of textile plies, steel weave, or steel cord, (ii) covers which are made up of either rubber or PVC (polyvinyl chloride) of different qualities, (ii) additional components of the conveyor belts which are as needed and are normally edge protection, impact protection, and longitudinal slitting prevention etc., and (iv) special construction elements which are the profiles on steep incline belts, cleats, or corrugated edges etc. The conveyor belts play a major part in the whole belt conveying system and have to overcome several and varied stresses.
Coolant – It is a material such as water or pressurized gas which transfers heat from the core. In case of grinding, it is the liquid used to cool the work during grinding and to prevent it from rusting. It also lubricates, washes away chips and grits, and aids in getting a finer finish. In metal cutting, the preferred term is cutting fluid.
Cooling and equalizing loop – The material entering the no twist block is required to be intensively cooled for final rolling at low temperatures. This is then to be followed by a sufficiently long equalizing section to allow the metallurgical properties to be achieved uniformly over the cross section of the finished wire rods. Without equalization section, the temperature difference between surface and core can be so large that different micro-structures can be created during the subsequent forming process. On the other hand, there are steel grades which are required to be rolled as hot as possible and for which a long equalizing section leads to deterioration in quality. The loop technology allows these two demands to be perfectly reconciled. The material from the intermediate train can take the short direct route or the route through the loop with additional water boxes and long equalizing sections before being rolled in no-twist blocks.
Cooling bed – A cooling bed is part of a rolling mill located at the end of the rolling mill. Cooling bed is the equipment where rolled products are cooled and at the same time item-by-item transferred to the roller table, on which they are transported to the finishing section. It supports and permits the hot rolled products from the last stand of the rolling mill to cool. Cooling bed naturally cools the material as well as cross transfers towards the discharge end. In a cooling bed the temperature of the entire length of the bar is to cool at the same time. If not, it develops stresses in the bar.
Cooling bed dividing shear – It is used to cut cooling bed lengths. This shear is normally designed for low surface temperatures. This shear is normally installed before entry to cooling bed. The cooling bed shear is normally either stop / start shear or continuous operating type. It is driven by the direct current motor drive. This shear is also normally controlled through programmable logic controller system and hence very close tolerance of cut length is achieved.
Cooling curve – It is a graph showing the relationship between time and temperature during the cooling of a material. It is used to find the temperatures at which phase changes occur. A property or function other than time can occasionally be used, e.g., thermal expansion.
Cooling rate – It is the average slope of the time-temperature curve taken over a specified time and temperature interval.
Cooling staves – They are also called cooling plates. A stave is a cooling device having one or more water channel, and is installed in numbers on the inner surface of the blast furnace to protect its steel shell and maintain the inner profile. The staves are conventionally made of cast iron but in high heat flux zones of the blast furnace now copper staves are also being used.
Cooling stresses These are the residual stresses in castings resulting from non-uniform distribution of temperature during cooling.
Cooling tower – It is a specialized heat exchanger in which air and water are brought into direct contact with each other in order to reduce the water’s temperature. As this occurs, a small volume of water is evaporated, reducing the temperature of the water being circulated through the tower.
Cooling water – It is used for the purpose of cooling. Cooling water is normally classified as either non-contact or indirect cooling water and contact or direct cooling water. Indirect cooling water application is the use of water for general cooling purposes where only equipment is being cooled and the water does not contact the material in process, off gases or fluids. Direct cooling water includes all applications of water where water comes in direct contact with material in process, process gas cleaning applications, process fluid applications (oils, cleaners, etc.) and rinse applications. Direct cooling waters are subject to treatment for recycling.
Coordinate measuring machines (CMMs) – These machines are used to inspect the dimensions of a finished product. Coordinate measuring machines consist of the machine itself and its probes and moving arms for providing measurement input, a computer for making rapid calculations and comparisons based on the measurement input, and the computer software which controls the entire system. Coordinate measuring machines are primarily characterized by their flexibility, being able to make several measurements without adding or changing tools.
Coordination compound – It is a compound with a central atom or ion bound to a group of ions or molecules surrounding it. It is also known as coordination complex.
Coordination number – In coordination compounds, it is the number of atoms bonded to a central atom or ion. In a space lattice, it is the number of nearest neighbours of a specific atom or ion.
Cope – In casting, it is the upper or top most section of a flask, mould, or pattern.
Copper – It is a chemical element. It is a soft, malleable, and ductile metal with very high thermal and electrical conductivity. Copper is used as a conductor of heat and electricity. It is a constituent of different metal alloys such as brass, and bronze etc. In steels, it is an austenite former. It decreases hot working. It is used as precipitation hardening alloying element. It is beneficial to atmospheric corrosion resistance when present in amounts exceeding 0.20 %.
Copper-accelerated salt-spray (CASS) test – It is an accelerated corrosion test for some electro-deposits and for anodic coatings on aluminum.
Copper brazing – It is a term improperly used to denote brazing with a copper filler metal.
Copper-head – It is a reddish spot in a porcelain enamel coating caused by iron pick-up during enameling, iron oxide left on poorly cleaned base metal, or burrs on iron or steel base metal which protrude through the coating and are oxidized during firing.
Copper losses – There is some loss of energy in a transformer because of the resistance of the primary winding to the magnetizing current, even when no load is connected to the transformer. This loss appears as heat generated in the winding and is also to be removed by the cooling system. When a load is connected to a transformer and electrical currents exist in both primary winding and secondary winding, further losses of electrical energy occur. These losses which are because of the resistance of the windings, are called copper losses or the ‘I2R’ losses.
Core -It is a specially formed material inserted in a mould to shape the interior or other part of a casting Which cannot be shaped as easily by the pattern. In a ferrous alloy prepared for case hardening, it is that portion of the alloy which is not part of the case. Typically considered to be the portion that (i) appears dark (with certain etchants) on an etched cross section, (ii) has an essentially unaltered chemical composition, or (iii) has a hardness, after hardening, less than a specified value. In a nuclear plant, core is the central heat-producing part of a nuclear reactor which contains the fuel assemblies. In case of wire rope, the core of a wire rope is the foundation of a wire rope. It runs through the centre of the rope. Its primary function is to support the wire strands in the rope and to maintain them in their correct relative positions during the operating life of the wire rope. The core supports the strands and helps to maintain their relative position under loading and bending stresses. Core in mining operation is the long cylindrical piece of rock, about 25 millimeters in diameter, brought to surface by diamond drilling.
Core assembly – In casting, it is a complex core consisting of a number of sections.
Core barrel – It is that part of a string of tools in a diamond drill hole in which the core sample is collected.
Core binder – In casting, it is a material used to hold the grains of core sand together.
Core blow – It is a gas pocket in a casting adjacent to a cored cavity and caused by entrapped gases from the core.
Core blower – It is a machine for making foundry cores using compressed air to blow and pack the sand into the core box.
Core box – In casting, it is a wood, metal, or plastic structure containing a shaped cavity into which sand is packed to make a core.
Cored bars – In powder metallurgy, these are compact of bar shapes heated by their own electrical resistance to a temperature high enough to melt its interior.
Core dryers – These are supports used to hold cores in shape during baking. These are constructed from metal or sand for conventional baking or from plastic material for use with dielectric core-baking equipment.
Cored solder – It is a solder wire or bar containing flux as a core.
Core filler – It is the material, such as coke, cinder, and saw-dust which is used in place of sand in the interiors of large cores. It is normally added to aid collapsibility.
Core for casting – It is separable part of a mould which normally is made of sand and a binder to create openings and various specially shaped cavities in castings.
Core forging – It is displacing metal with a punch to fill a die cavity. Also, it is the product of such an operation.
Core (for rolled products) – It is a hollow cylinder on which a coiled product can be wound which forms the inside diameter of a coil.
Core knock-out machine – In casting, it is a mechanical device for removing cores from castings.
Coreless induction furnace – It has a fairly simple construction. It basically consists of a refractory vessel and the surrounding coil borne by a steel frame. When an alternating current flows through the coil, it creates an electromagnetic field which in turn induces eddy currents in the charged material. This charge material gets heated up as per Joule’s law and with further heat the charge material melts. The main component of the coreless IF consists of a crucible, a power supply unit consisting of transformer, inverter and capacitor bank, the charging arrangement, the cooling system for the power supply and furnace coil, process control system, and the fume extraction equipment. In this furnace, the heart of the furnace is the coil, which consists of a hollow section of heavy duty, high conductivity copper tubing which is wound in the form of a helical coil. Coil shape is contained within a steel shell and magnetic shielding is used to prevent heating of the supporting shell. To protect it from overheating, the coil is water-cooled, the water being recirculated after cooling in a cooling tower. The shell is supported on trunnions on which the furnace tilts to facilitate pouring. The crucible is formed by ramming a granular refractory between the coil and a hollow internal former which is melted away with the first heat leaving a sintered lining.
Core losses – Since magnetic lines of force in a transformer are constantly changing in value and direction, heat is developed because of the hysteresis of the magnetic material (friction of the molecules). This heat is to be removed. Hence, it represents an energy loss of the transformer. High temperatures in a transformer drastically shortens the life of insulating materials used in the windings and structures. For every 8 deg C temperature rise, life of the transformer is cut by one-half, hence, maintenance of cooling systems is critical. Losses of energy, which appears as heat because of both the hysteresis and the eddy currents in the magnetic path, is known as core losses. Since these losses are because of the alternating magnetic fields, they occur in a transformer whenever the primary is energized, even though no load is on the secondary winding.
Core melt – It is the overheating of the core of a nuclear reactor which results in the core melting.
Core oil – It is a binder for core sand which sets when baked and is destroyed by the heat from the cooling casting.
Core plates – These are heat-resistant plates used to support cores during baking. They can be metallic or non-metallic, the latter being a requisite for dielectric core baking.
Core print – It is the projections attached to a pattern in order to form recesses in the mould at points where cores are to be supported.
Core rod – In powder metallurgy, it is a member of a die assembly used in moulding a hole in a compact.
Core sand – In casting, it is the sand used for making cores to which a binding material has been added to get good cohesion and permeability after drying. Normally sand low in clays is used.
Core shift – It is a variation from the specified dimensions of a cored casting section because of a change in position of the core or misalignment of cores in assembly.
Core vents – These are a wax product, round or oval in form, used to form the vent passage in a core. It is also a metal screen or slotted piece used to form the vent passage in the core box used in a core blowing machine. These are also the holes made in the core for the escape of gas.
Core wash – It is a suspension of a fine refractory applied to cores by brushing, dipping, or spraying to improve the surface of the cored portion of the casting.
Core wires or rods – These are reinforcing wires or rods for fragile cores, frequently preformed into special shapes.
Corex process – The main feature of the Corex process is the separation of the iron reduction and smelting operations into two separate reactors, namely reduction shaft and melter-gasifier. In the two-stage operation of the process direct reduced iron produced from a shaft furnace is charged into a melter-gasifier for smelting. In the melter-gasifier, non-coking coal is gasified by injecting oxygen and pre-reduced iron ore / pellets are melted. The outgoing gas is used for reduction of iron ore / pellets in the upstream shaft furnace.
Coring – It is a condition of variable composition between the centre and surface of a unit of micro-structure (such as a dendrite, grain, carbide particle). It results from non-equilibrium solidification, which occurs over a range of temperature. It is also a central cavity at the butt end of a rod extrusion, sometimes called extrusion pipe.
Corner cracks – These are cracks present as a defect in the edge of the continuous cast steel product. They appear due to high temperature variations in the liquid steel, higher aluminum content in the steel, higher sulphur level in the steel, non-uniform edge temperature, excess friction in the edges during casting because of non-uniform distribution of casting powder, and lower superheat of the steel.
Corner flange weld – It is a flange weld with only one member flanged at the joint.
Corner joint – It is a joint between two members located approximately at right angles to each other.
Corner turn-up – It is a distortion, buckle, or twist condition which causes the corner(s) of the sheet to deviate from a perfectly flat plane on which it rests.
Corona – In resistance welding, it is the area sometimes surrounding the nugget of a spot weld at the faying surfaces which provides a degree of solid-state welding.
Correction signal – A correction signal is the signal used to control power to the actuator to set the level of the input variable.
Corrodkote test – The Corrodkote test is an accelerated test used for determining plating corrosion resistance of electro-deposits. It is performed by putting Corrodkote mud as well as a dried sample under testing within a moist chamber.
Corrosion – It is the wasting away of metal because of chemical action. It is the chemical or electro-chemical reaction between a material, normally a metal, and its environment which produces a deterioration of the material and its properties. In case of galvanized steel, zinc chemically reacts with elements in the atmosphere, thereby sacrificially corroding to prevent corrosion of the underlying steel. In a boiler, it is normally caused by the presence of oxygen, carbon di-oxide, or an acid.
Corrosion effect – It is a change in any part of the corrosion system caused by corrosion.
Corrosion embrittlement – It is the severe loss of ductility of a metal resulting from corrosive attack, normally inter-granular and frequently not visually apparent.
Corrosion-erosion – It is a conjoint action involving corrosion and erosion in the presence of a moving corrosive fluid, leading to the accelerated loss of material.
Corrosion, exfoliation – It is the corrosion which progresses approximately parallel to the metal surface, causing layers of the metal to be elevated by the formation of corrosion product.
Corrosion failure of refractories – It is the most common cause of premature failures of refractories. However, corrosion is infrequently the cause of premature failure for technical ceramics. Corrosion of refractories occurs mainly when refractory materials are in contact with metallurgical slags or glasses (solids + liquid type of reaction), but atmosphere corrosion also occurs under specific circumstances (under reducing or oxido-reducing conditions), as, for example, under attack from carbon mono-oxide or alkalis and other condensable gases (solid + gas type of reaction).
Corrosion fatigue – It is the process in which a metal fractures prematurely under conditions of simultaneous corrosion and repeated cyclic loading at lower stress levels or fewer cycles than are needed in the absence of the corrosive environment.
Corrosion fatigue strength – It is the maximum repeated stress which can be endured by metal without failure under definite conditions of corrosion and fatigue and for a specific number of stress cycles and a specified period of time.
corrosion, galvanic _ It is the corrosion which is associated with the current of galvanic cell consisting of two dissimilar conductors in an electrolyte or two similar conductors in dissimilar electrolytes. A metal corrodes if it is anodic to the dissimilar metal.
Corrosion inhibitor – It is the substance which retards some specific chemical reaction causing corrosion.
Corrosion, intergranular – It is the corrosion which is occurring preferentially at grain boundaries. It is also termed as inter-crystalline corrosion.
Corrosion, pitting – It is the localized corrosion which results in small pits or crater in a metal surface.
Corrosion potential (Ecorr) – It is the potential of a corroding surface in an electrolyte, relative to a reference electrode. It is also called rest potential, open-circuit potential, or freely corroding potential.
Corrosion product – It is the substance formed as a result of corrosion.
Corrosion protection – It is the modification of a corrosion system so that corrosion damage is mitigated.
Corrosion rate – It is the corrosion effect on a metal per unit of time. The type of corrosion rate used depends on the technical system and on the type of corrosion effect. Hence, corrosion rate can be expressed as an increase in corrosion depth per unit of time (penetration rate, for example, millimeter or micrometer per year) or the mass of metal turned into corrosion products per unit area of surface per unit of time (weight loss, for example, grams per square metre per year). The corrosion effect can vary with time and cannot be the same at all points of the corroding surface. Hence, reports of corrosion rates are to be accompanied by information on the type, time dependency, and location of the corrosion effect.
Corrosion resistance – It is the ability of a material to withstand contact with ambient natural factors or those of a particular, artificially created atmosphere, without degradation or change in properties. For metals, this can be pitting or rusting, while for organic materials it can be crazing.
Corrosion, stress-cracking – It is the failure by cracking resulting from selective directional attack caused by the simultaneous interaction of sustained tensile stress at an exposed surface with the chemical or electro-chemical effects of the surface environment. The term frequently is abbreviated SCC, which correctly stands for stress-corrosion cracking.
Corrosion system – It is the system consisting of one or more metals and all parts of the environment which influence corrosion.
Corrosion, water stain – It is the superficial oxidation of the surface with a water film, in the absence of circulating air, held between closely adjacent metal surfaces.
Corrosive wear – It is the wear in which chemical or electro-chemical reaction with the environment is significant. It is defined as the degradation of materials in which both corrosion and wear mechanisms
are involved. The combined effects of wear and corrosion can result in total material losses which are much higher than the additive effects of each process taken alone, which indicates synergism between the two processes.
Corrosive wear failure – It is the failure of a material because of corrosion wear.
Corrosivity – It is the tendency of an environment to cause corrosion in a given corrosion system.
Corrugated sheet – It is a generic term which means any type of sheet steel strengthened for use in construction by having a series of alternating grooves and ridges forced into it. Technically, this can mean any metal roofing or wall panel.
Corrugating – It is the forming of sheet metal into a series of straight, parallel alternate ridges and grooves with a rolling mill equipped with matched roller dies or a press brake equipped with a specially shaped punch and die.
Corrugations – In metal forming, these are transverse ripples caused by a variation in strip shape during hot or cold reduction.
Corten steels – These steels are distinguished by their high weather resistant properties. The alloying of steel with copper and chromium ensures the formation of a firmly adhering protective layer of rust which protects the steel from corrosion in atmospheric condition. The protective layer of rust also makes an attractive appearance on the steel surface.
Corundum – Corundum is a crystalline form of aluminium oxide typically containing traces of iron, titanium, vanadium, and chromium. It is an aluminum oxide which normally forms hexagonal barrel-shaped prisms which taper at both ends or as thin tabular hexagonal plates. It has a hardness of 9 on the Mohs scale. It has no dominant cleavage and it fractures in a conchoidal manner. It is used as an abrasive.
Cost benefit analysis – It is a tool which is used for the determination of the worth of a project, programme or policy. It is a systematic approach for the estimation of the strengths and weaknesses of alternatives and is used to determine options which provide the best approach to achieve benefits from the project. It is the comparison of costs and benefits of the project to decide whether it can be undertaken. In cost benefit analysis; both the tangible and intangible costs as well as tangible and intangible benefits are considered.
Cottrell process – It is the process for the removal of solid particulates from gases with electrostatic precipitation.
Coulomb – It is the quantity of electricity which is transmitted through an electric circuit in 1 second when the current in the circuit is 1 ampere. It is the quantity of electricity which deposits 0.001118 grams of silver.
Coulomb friction – It is a term used to indicate that the frictional force is proportional to the normal load.
Coulomb’s laws – Two laws propounded in 1699 which state that (i) friction force is proportional to normal force, and (ii) friction force is independent of the size of the contact area.
Coulomb-Mohr fracture criterion – It is a theory of fracture based on experimental values for both tensile and compressive strength in which fracture on a plane is hypothesized to occur when a critical combination of normal stress and shear stress occur on the plane (maximum pressure reduced shear stress). The critical combination of stresses is assumed to be a linear relationship given by the equation |T| + mu.S = Ti (uniaxial load) where ‘T’ and ‘S’ are shear stress and normal stress, respectively, and ‘mu’ and Ti are material constants.
Coulometer – It is an electrolytic cell arranged to measure the quantity of electricity by the chemical action produced in accordance with Faraday’s law.
Coulometry – It is an electrochemical technique in which the total number of coulombs consumed in an electrolysis is used for determining the quantity of substance electrolyzed.
Count – It consists of measuring and monitoring the number of ionizing radiation particles present using radiation detection equipment.
Counter-blow equipment it is the equipment with two opposed rams which are activated simultaneously to strike repeated blows on the work-piece placed midway between them.
Counter-blow hammer – It is a forging hammer in which both the ram and the anvil are driven simultaneously toward each other by air or steam pistons.
Counter-boring – It is the removal of material to enlarge a hole for part of its depth with a rotary, pilot guided, end cutting tool having two or more cutting lips and normally having straight or helical flutes for the passage of chips and the admission of a cutting fluid.
Counter electrode – In emission spectroscopy, it is the electrode which is used opposite to the self-electrode or supporting electrode and which is not composed of the sample to be analyzed. In voltammetry, it is the current between the working electrode and counter electrodes is measured.
Counter-formal surfaces – These are the surfaces whose centres of curvature are on the opposite sides of the interface, as in rolling element bearings or gear teeth. In wear testing, this term is sometimes used to indicate that the test sample surfaces are not conformal (e.g., with a sphere-on-flat or flat block-on rotating ring configuration). In such cases, the nominal contact area of at least one of the test piece surfaces increases as the quantity of wear increases.
Counter-lock – It is a jog in the mating surfaces of dies for preventing the lateral die shift caused by side thrust during the forging of irregularly shaped pieces.
Counter-sinking – It is beveling or tapering the work material around the periphery of a hole creating a concentric surface at an angle less than 90-degree with the centre line of the hole for the purpose of chamfering holes or recessing screw and rivet heads.
Country rock – It is loosely used to describe the general mass of rock adjacent to an orebody. It is also known as the host rock.
Couple – In galvanic corrosion, It is a pair of dissimilar conductors, normally metals, in electrical contact.
Coupling – It is a mechanical element part that connects two shafts together to accurately transmit the power from the drive side to the driven side while absorbing the mounting error (misalignment) etc. In case of pipe fitting, a coupling connects two pipes to each other. If the size of the pipe is not the same, the fitting can be called a reducing coupling or reducer, or an adapter. By convention, the term ‘expander’ is not normally used for a coupling which increases pipe size, instead the term ‘reducer’ is used. In rolling mills, couplings serve for transfer of torque of the driving train to the work rolls. Their function consists in absorbing roll force impacts (shocks) and prevention of the transfer these shocks to the electric motor. The common types of coupling used in the rolling mills are cardan shaft coupling, gear coupling, and universal coupling.
Covalent bond – It is a primary bond arising from the reduction in energy associated with overlapping half-filled orbitals of two atoms.
Coupon – It is a piece of metal from which a test sample is to be prepared. It is frequently an extra piece (as on a casting or forging) or a separate piece made for test purposes (such as a test weldment).
Cover coat – It is a porcelain enamel finish applied to and then fused over a ground coat or applied directly to the metal substrate and then fused.
Cover core – It is a core set in place during the ramming of a mould to cover and complete a cavity partly formed by the withdrawal of a loose part of the pattern. It is also used to form part or all of the cope surface of the mould cavity. Also, it is a core placed over another core for creating a flat parting line.
Covered electrode – It is a composite filler metal electrode consisting of a core of a bare electrode or metal cored electrode to which a covering sufficient to provide a slag layer on the weld metal has been applied. The covering can contain materials providing such functions as shielding from the atmosphere, deoxidation, and arc stabilization and can serve as a source of metallic additions to the weld.
Covering area – It is the yield expressed in terms of a given number of square meters per kilogram.
Covering power – It is the ability of a solution to give satisfactory plating at very low current densities, a condition which exists in recesses and pits. This term suggests an ability to cover, but not necessarily to build up, a uniform coating, whereas throwing power suggests the ability to get a coating of uniform thickness on an irregularly shaped object. It is also the degree to which a porcelain enamel coating obscures the underlying surface. It is also the ability of a glaze to uniformly and completely cover the surface of the fired ceramic ware.
Crack – It is a fracture type discontinuity characterized by a sharp tip and high ratio of length and width to opening displacement. It is also a line of fracture without complete separation.
Crack bifurcation – It is the splitting of a crack into two paths, or the intersection of a crack with a pre-existing crack.
Crack extension – It is an increase in crack size.
Crack-extension force – It is the elastic energy per unit of new separation area which is to be made available at the front of an ideal crack in an elastic solid during a virtual increment of forward crack extension.
Crack-extension resistance – It is a measure of the resistance of a material to crack extension, expressed in terms of the stress-intensity factor, the crack-extension force, or values of ‘J’ derived using the J-integral concept.
Crack growth – It is the rate of propagation of a crack through a material due to a static or dynamic applied load.
Crack-growth rate – It is the rate of propagation of a crack through a material because of the statically or dynamically applied load.
Cracking – In coatings, it consists of breaks in the coating which extend through to the underlying surface. In lubrication technology, cracking is the process of converting unwanted long-chain hydro-carbons to shorter molecules by thermal or catalytic action.
Crack length (depth) – In fatigue and stress-corrosion cracking, the physical crack size is used to determine the crack growth rate and the stress-intensity factor. For a compact-type sample, crack length is measured from the line connecting the bearing points of load application. For a centre-crack tension sample, crack length is measured from the perpendicular bisector of the central crack.
Crack mouth opening displacement (CMOD) – In a plane strain fracture toughness test sample, it is the opening displacement of the notch surfaces at the notch and in the direction perpendicular to the plane of the notch and the crack. The displacement at the mouth is called the crack mouth opening displacement (CMOD).
Crack opening displacement – In a plane strain fracture toughness test sample, it is the opening displacement of the notch surfaces at the notch and in the direction perpendicular to the plane of the notch and the crack. The displacement at the tip is called the crack tip opening displacement (CTOD), and that at the mouth, it is called the crack mouth opening displacement (CMOD).
Crack-plane orientation – It is an identification of the plane and direction of a fracture in relation to product geometry. This identification is designated by a hyphenated code, the first letter(s) representing the direction normal to the crack plane and the second letter(s) designating the expected direction of crack propagation.
Crack plane orientation and growth direction system – It is a three-letter identification system used to identify the longitudinal (L), transverse (T), and short transverse (S) direction of the applied stress normal to the plane on which the crack propagates and the direction of crack growth. It is used for both prismatic and cylindrical sections. For example, a L-T orientation indicates a stress in the longitudinal (or rolling) direction, and crack propagation is in the wide transverse direction.
Crack resistance curve it is a graph of resistance of a material to slow, stable crack extension, expressed in the same units as the stress intensity factor, or the crack extension force as a function of the amount (length) of slow, stable crack extension. Comparison of the crack driving forces with this curve provides an estimate of the conditions for crack growth instability.
Crack size – It is a lineal measure of a principal planar dimension of a crack. This measure is normally used in the calculation of quantities descriptive of the stress and displacement fields. In practice, the value of crack size is got from procedures for measurement of physical crack size, original crack size, or effective crack size, as appropriate to the situation under consideration.
Crack tip opening displacement (CTOD) – In a plane strain fracture toughness test sample, it is the opening displacement of the notch surfaces at the notch and in the direction perpendicular to the plane of the notch and the crack. The displacement at the tip is called the crack tip opening displacement (CTOD).
Crack-tip plane strain – It is a stress-strain field, near a crack-tip, which approaches plane strain to the degree needed by an empirical criterion.
Cranes – Cranes are industrial machines which are mainly used for materials movements in construction sites, production shops, assembly lines, storage areas, power stations and similar places. Their design features vary widely according to their major operational specifications such as type of motion of the crane structure, weight and type of the load, location of the crane, geometric features, operating mechanisms, and environmental conditions. Cranes play an important role in the handling of materials by raising and moving loads, the mass of which is within their nominal capacity. There can, however, be wide variations in the duty, both for a single crane type, for example overhead travelling cranes, or between different crane types, for example between a builder’s tower crane and a heavy-lift dockside crane. The design of the crane has to take into account the conditions of service, in order to reach an appropriate level of safety and useful life.
Crane capacity – It is the rated load, which is required to be lifted. Rated load means the maximum load for which a crane or individual hoist is designed and built by the manufacturer and shown on the equipment identification plate. The rated capacity of crane is the live load which can be lifted by the crane. The rated load is defined as the maximum working load suspended under the load hook. Load block and ropes are not included in the rated load.
Crane scales – They consist of dynamometer placed between lifting hoist and the load to indicate the weight of the load.
Crane steel structure – It has a single or double girder crane construction as per the span and the maximum load handling capacity.
Crank – It is an arm attached at a right angle to a rotating shaft by which circular motion is imparted to or received from the shaft. When combined with a connecting rod, it can be used to convert circular motion into reciprocating motion, or vice versa.
Crank pin bearing – It is a bearing at the larger (crankshaft) end of a connecting rod in an engine. It is also known as bottom-end bearing, crankpin bearing, and large-end bearing.
Crank press – It is a mechanical press whose slides are actuated by a crank-shaft.
Crank shears – These shears can be designed as (i) continuously running shears, (ii) start-stop shears, and (iii) coupling shears with coupling- brake combination. These shears are used for cropping, dividing, or emergency cutting during cobble. Shear start is initiated by pulse generator. Crank shears can be crank lever shear or double crank shears.
Crater – In arc welding, it is a depression at the termination of a weld bead or in the molten weld pool.
Crater crack – It is a crack in the crater of a weld bead.
Cratering – It is the depressions on coated surfaces caused by excess lubricant. Cratering results when paint is too thin and later ruptures, leaving pinholes and other voids. Use of less-thinner in the coating can reduce or eliminate cratering, as can the use of less lubricant on the part.
Crater wear – It is the wear which occurs on the rake face of a cutting tool because of the contact with the material in the chip which is sliding along that face.
Crawler crane – A crawler is a crane mounted on an undercarriage with a set of tracks which is also called crawlers. These crawlers provide stability and mobility to the crane. Crawler cranes have both advantages and disadvantages depending on their use. Their main advantage is that they can move around on site and perform each lift with little set up, since the crane is stable on its tracks with no outriggers. A crawler crane is also capable of travelling with a load. The main disadvantage is that these cranes are very heavy, and cannot easily be moved from one job site to another without significant expense. Typically, a large crawler is to be disassembled and moved by trucks, rail cars or ships to its next location. Crawler cranes range in lifting capacity from around 35 tons to 3,000 tons.
Crawling – In porcelain enamel, It is a condition similar to tearing which occurs when firing a sprayed enamel coating over another coating already fired. It is characterized by the aggregation of the top-coat
into balls or irregularly shaped islands during firing, hence exposing the base coat layer.
Craze cracking – it is the irregular surface cracking of a metal associated with thermal cycling.
Crazing – It is a network of fine hairline cracks in a coating. It is also cracking which occurs in fired glazes or other ceramic coatings because of the critical tensile stresses. In porcelain enamel, it is almost-invisible lines in the finished surface which extend down to the base metal. It is also a macroscopic effect of numerous surface tears, transverse to the rolling direction, which can occur when the entry angle into the cold mill work rolls is large.
Crease – It is a sharp deviation from flat in the sheet which is transferred from processing equipment subsequent to the roll bite.
Creep – Creep is the property of materials which results in progressive deformation when a constant load is applied over time. Deformation occurs as a result of long-term exposure to high levels of stress which is still below the yield strength of the material. It is the time-dependent strain occurring under stress. The creep strain occurring at a diminishing rate is called primary creep, that occurring at a minimum and almost constant rate is called secondary creep, and that occurring at an accelerating rate is called tertiary creep.
Creep deformation – It is a permanent inelastic strain which occurs when a material is subjected to a sustained stress. The rate at which this deformation occurs depends not only on the magnitude of the applied stress, but also on time and temperature.
Creep-feed grinding – It is a grinding process which produces deeper cuts at slow traverse rates.
Creep limit – It is the maximum stress which causes less than a specified quantity of creep in a given time. It is also the maximum nominal stress under which the creep strain rate decreases continuously with time under constant load and at constant temperature. Sometimes it is used synonymously with creep strength.
Creep rate – It is the slope of the creep-time curve at a given time. It is the deflection with time under a given static load.
Creep ratio – In a ball bearing, it is the ratio of the creep velocity to sweep velocity.
Creep recovery – It is the time-dependent decrease in strain in a solid, following the removal of force.
Creep-rupture – It is the tensile fracture of a material subjected to sustained high stress levels over a period of time and occurs when a material strain capacity is reached.
Creep-rupture embrittlement – It is the embrittlement under creep conditions. Failure occurs by intergranular cracking of the embrittled material.
Creep-rupture strength – It is the stress which causes fracture in a creep test at a given time, in a specified constant environment. This is sometimes referred to as the stress-rupture strength.
Creep-rupture test – It is a test in which progressive sample deformation and the time for rupture are both measured. In general, deformation is much higher than that developed during a creep test. It is also known as stress-rupture test.
Creep strain – It is the time-dependent total strain (extension plus initial gauge length) produced by applied stress during a creep test.
Creep strength – It is the stress which causes a given creep strain in a creep test at a given time in a specified constant environment.
Creep stress – It is the constant load divided by the original cross-sectional area of the sample.
Creep test – It is a method of determining the extension of metals under a given load at a given temperature. The determination normally involves the plotting of time-elongation curves under constant load. A single test can extend over several months. The results are frequently expressed as the elongation (in millimeters) per hour on a given gauge length (e.g., 25 mm).
Cresol – Cresols (also known as hydroxytoluene, toluenol, benzol or cresylic acid) are a group of aromatic organic compounds. They are widely-occurring phenols (sometimes called phenolics) which can be either natural or manufactured.
Creosote oil – It is also known as wash oil and has boiling range of 230 deg C to 290 deg C. It is reported to have some 162 compounds. However, only a limited number (lesser than 20) are at levels exceeding 1 % but these constitute the major portion of creosote oil. It contains besides small amounts of naphthalene, naphthalene derivatives, indole, diphenyl, acenaphthene, diphenylene oxide, fluorene, phenol derivatives (2 %) and quinoline base (4 % to 6 %).
Crevice corrosion – It refers to the corrosion occurring in cracks or crevices formed between two surfaces (made from the same metal, different metals or even a metal and a non-metal). This type of corrosion is initiated by the restricted entrance of oxygen from the air by diffusion into the crevice area leading to different concentrations of dissolved oxygen in the common electrolyte (the so-called aeration cell). Again, the two partial reactions take place on different parts of the surface. Oxygen reduction takes place in the outer areas with higher oxygen concentrations easily accessible by the surrounding air, whereas the anodic metal dissolution occurs in the crevice area resulting in localized attack (e.g. pitting). It can also occur under washers or gaskets, when the entry of water underneath is not prevented).
CRI – CRI is the coke reactivity index. It is measured by a laboratory test designed to simulate the loss of coke through reaction in the reducing atmosphere, as the coke makes its way down the blast furnace. Coke is heated up to 950 deg C in an inert atmosphere and held at that temperature in an atmosphere of carbon di-oxide. The coke is cooled down under the inert atmosphere and the loss in weight expressed as a percentage is the CRI value of the coke. CRI measures the ability of coke to withstand breakage at room temperature and reflects coke behaviour outside the blast furnace and in the upper part of the blast furnace.
Crimping -It is the forming of relatively small corrugations in order to set down and lock a seam, to create an arc in a strip of metal, or to reduce an existing arc or diameter.
Crisis – It is an event which harms an organization, its facilities, its finances or its reputation within a short period of time. A crisis can occur as a result of an unpredictable event or as an unforeseeable consequence of some event that had been considered a potential risk. In either case, crisis almost invariably requires that decisions be made quickly to limit damage to the organization.
Crisis management – It is the application of strategies designed to help the organization deal with a sudden and significant negative event. Crisis management is the art of making decisions to head off or mitigate the effects of such an event, often while the event itself is unfolding. This often means making decisions under stress and without the support of key pieces of information.
Criteria – UNFC (United Nations Framework Classification for Resources) utilizes three fundamental criteria for reserve and resource classification namely (i) favourability of environmental-socio-economic conditions in establishing the viability of the project (E axis), (ii) maturity of technology, studies and commitments necessary to implement the project (F axis), and (iii) degree of confidence in the estimate of quantities of products from the project (G axis). These Criteria are each subdivided into categories and sub-categories, which are then combined in the form of classes or sub-classes.
Critical / criticality – It is a medium containing a fissile nuclear material becomes critical when neutrons are produced (by the fission of this material) at the same rate as they disappear (through absorption and leakage to the outside). The point at which a nuclear chain reaction becomes self-sustaining.
Critical anodic current density – It is the maximum anodic current density observed in the active region for a metal or alloy electrode which shows active-passive behaviour in an environment.
Critical cooling rate – It is the minimum rate of continuous cooling for preventing undesirable transformations. For steel, unless otherwise specified, it is the slowest rate at which austenite can be cooled from above critical temperature to prevent its transformation above the martensite start temperature.
Critical current density – In an electrolytic process, it is a current density at which an abrupt change occurs in an operating variable or in the nature of an electrodeposit or electrode film.
Critical curve – In a binary or higher order phase diagram, it is a line along which the phases of a heterogeneous equilibrium become identical.
Critical diameter – It is the diameter of the bar which can be fully hardened with 50 % martensite at its centre.
Critical dimension – It is a dimension on a part which is to be held within the specified tolerance for the part to function in its application. A non-critical tolerance can be for cost or weight savings or for manufacturing convenience, but is not essential for the products.
Critical flaw size – It is the size of a flaw (defect) in a structure which causes failure at a particular stress level.
Critical humidity – It is the relative humidity above which the atmospheric corrosion rate of some metals increases sharply.
Critical illumination – It is the formation of an image of the light source in the object field.
Critical mass – It is the smallest quantity of fissile material needed to support a self-sustaining nuclear chain reaction. The critical mass of a fissionable material depends upon its nuclear properties (e.g. the nuclear fission cross-section), its density, its shape, its enrichment, its purity, its temperature and its surroundings.
Critical micelle concentration – It is the concentration of a micelle at which the rate of increase of electrical conductance with increase in concentration levels off or proceeds at a much slower rate.
Critical pigment volume concentration (CPVC) – It is the volume percent of pigment in a coating in which the pigment particles are surrounded by resin so that no free surface pigment exists.
Critical pitting potential – It is the lowest value of oxidizing potential at which pits nucleate and grow. It is dependent on the test method used.
Critical point – It is the temperature or pressure at which a change in crystal structure, phase, or physical properties occur. It is also termed as the transformation temperature. In an equilibrium diagram, critical point is that combination of composition, temperature, and pressure at which the phases of an inhomogeneous system are in equilibrium.
Critical pressure – It is that pressure above which the liquid and vapour states are no longer distinguishable.
Critical rake angle – It is the rake angle at which the action of a V-point tool changes from cutting to plowing.
Critical raw materials – Critical raw materials are materials or substances used in the primary production or manufacturing of goods. Critical raw materials are raw materials which are economically and strategically important for the economy but have a high-risk associated with their supply.
Critical shear stress – It is the shear stress needed to cause slip in a designated slip direction on a given slip plane. It is called the critical resolved shear stress if the shear stress is induced by tensile or compressive forces acting on the crystal.
Critical strain – In mechanical testing, it is the strain at the yield point. It is also the strain just sufficient to cause recrystallization, since the strain is small (normally only a few percent), recrystallization takes place from only a few nuclei, which produces a recrystallized structure consisting of very large grains.
Critical stress-intensity factor – It is a scaling factor, usually denoted by the symbol ‘K’, used in linear-elastic fracture mechanics to describe the intensification of applied stress at the tip of a crack of known size and shape. At the onset of rapid crack propagation in any structure containing a crack, the factor is called the critical stress-intensity factor, or the fracture toughness.
Critical surface – In a ternary or higher order phase diagram, it is the area upon which the phases in equilibrium become identical.
Critical temperature – It is that temperature above which the vapour phase cannot be condensed to liquid by an increase in pressure. It is synonymous with critical point if pressure is constant.
Critical temperature range – It is synonymous with transformation ranges, which is the preferred term. Transformation ranges are those ranges of temperature within which austenite forms during heating and transforms during cooling. The two ranges are distinct, sometimes overlapping but never coinciding. The limiting temperatures of the ranges depend on the composition of the alloy and on the rate of change of temperature, particularly during cooling.
Croning process – In casting, it is a shell moulding process which uses a phenolic resin binder. Sometimes it is referred to as cronin process or Chronizing. In the process, dry, free-flowing moulding material, consisting of resin coated sand is added by means of gravity or by application of pressure onto or into the tool.
Crop – It is an end portion of an ingot, slab, or bloom which is cut off as scrap. It is also means to shear a bar or billet.
Crop and cobble shear – It is used in hot rolling mills is to crop front end, tail end, as well as to segment cutting in case of eventualities. These shears are normally of start / stop type and are driven either with flywheel mounted pneumatic clutch / brake or with direct current motor driven. These shears are controlled through programmable logic control system and provide very close tolerance of the cut length.
Cross – It is a pipe fitting. It has one inlet and three outlets, or vice versa and like tees come in equal and reducing forms. A cross is more expensive than two tees but has the advantage of reduced space and needs less manpower to install.
Cross-bar or arm conveyor – This type of conveyor consists of a single or two strands of endless chain, to which are attached spaced, removable or fixed arms (or cross members) from which materials are hung or festooned. The arms can be replaced by shelves / trays to support packages or objects to carry them in a vertical or an inclined path. Special arms are designed to suit specific load configuration. Depending on the design of arms, they are called by different names, some of which are (i) pendent conveyor, (ii) pocket conveyor, (iii) wire mesh deck conveyor, (iv) removable crossbar conveyor, (v) fixed cross-bar (or arm) conveyor, and (vi) swing tray conveyor.
Cross breaks – It is same as coil breaks. Cross breaks are creases or ridges in sheet or strip which appear as parallel lines across the direction of rolling and which normally extend the full width of the sheet or strip.
Cross-country rolling mill – It is a rolling mill in which the mill stands are so arranged that their tables are parallel with a transfer (or crossover) table connecting them. Such a mill is used for rolling structural shapes, rails, and any special form of bar stock not rolled in the ordinary bar mill.
Cross direction – It is a direction or plane perpendicular to the direction of working. In rolled plate or sheet, the direction across the width is frequently called long transverse, while the direction through the thickness is called short transverse.
Cross forging – It is the preliminary working of forging stock in flat dies to develop mechanical properties, particularly in the centre portions of heavy sections.
Cross hatching – it is a macroscopic effect of numerous surface tears, transverse to the rolling direction, which can occur when the entry angle into the cold mill work rolls is large.
Cross helical gears – This type of gear is recommended only for a narrow range of applications where loads are relatively light. Since contact between teeth is a point instead of a line, the resulting high sliding loads between the teeth requires extensive lubrication. Hence, very little power can be transmitted with cross helical gears.
Cross lay – In wire ropes, the cross lay is referred to as the point contact lay, as each wire is in contact with each other. The laying of the wires is carried out in such a way that the lay angle is almost equal for each layer of wire of the same diameter. The length of the wires in each layer is also to be the same and the wires of each layer are in contact with each other. Hence, the tension stress which works on the wire becomes uniform, but the bending stress due to the contact points is added and so the fatigue resistance is not as great.
Cross linking – With thermosetting and certain thermoplastic polymers, the setting up of chemical links between the molecular chains. When extensive, as in majority of the thermosetting resins, cross linking makes an infusible supermolecule of all the chains. In rubbers, the cross linking is just enough to join all molecules into a network.
Cross rolling – It is rolling of metal or sheet or plate so that the direction of rolling is around 90-degree from the direction of a previous rolling.
Cross section – In technical drawing a cross-section, being a projection of an object onto a plane that intersects it, is a common tool used to depict the internal arrangement of a 3-dimensional object in two dimensions. It is traditionally cross-hatched with the style of cross-hatching frequently indicating the types of materials being used.
Cross-sectional area – It is the area measured at right angles to the molten metal flow stream at any specified portion of the gating system.
Cross section drawing – Cross-section drawing allows the engineer look at the different components of an object vertically. This 2-dimensional (2-D) drawing is helpful to provide an overview of both the visible and hidden components of the object.
Cross-wire weld – It is a weld made at the junction between crossed wires or bars.
Crown – It is the upper part (head) of a forming press frame. On hydraulic presses, the crown normally contains the cylinder. On mechanical presses, the crown contains the drive mechanism. In rolls, it is a shape (crown) ground into a flat roll for ensuring flatness of cold-rolled and hot-rolled sheets and strips. It is also a contour on a sheet or roll where the thickness or diameter increases from edge to centre.
Crown sheet – In a fire-box boiler, it is the plate forming the top of the furnace.
Crucible – It is a vessel or pot, made of a refractory substance or of a metal with a high melting point, used for melting metals or other substances.
Crucible furnace – It is a melting or holding furnace in which the molten metal is contained in a pot-shaped (hemispherical) shell. Electric heaters or fuel-fired burners outside the shell generate the heat which passes through the shell (crucible) to the molten metal.
Crude benzol – Benzol (also known as benzole) recovered from coke oven gas is called as crude benzol. It contains small quantities of a large number of impurities which consists of the unsaturated and sulphur compounds. These impurities have negative effects on the organic processes. Benzol is the name normally applied in the chemical industry to a mixture of hydrocarbons of the benzene series, in which benzene itself predominates, in association with certain of its homologues and various impurities.
Crude ore – Crude Ore means all ores, metals, minerals and other products containing mineral substances mined for removal from the mine site, which have not been subject to further processing or concentrating. It is also called run-of-mine ore.
Crude steel – Crude steel is the term used for the first solid steel product which is produced during the solidification of liquid steel in a steel melting shop. Crude steel is part of saleable steel when it is supplied to customers for its use or for further processing. Crude steel is normally processed into finished steel either by rolling or by forging processes.
Crude tar – It is also known as coal tar. It is the by-product generated during the high temperature carbonizing of coking coal for the production of the metallurgical coke in the by-product coke ovens. It is a black, viscous, sometimes semi-solid, fluid of peculiar smell, which is condensed together with aqueous ‘gas-liquor’ (ammoniacal liquor), when the volatile products of the carbonization of coking coal are cooled down. It is acidic in nature and is water insoluble. It is composed primarily of a complex mixture of condensed-ring aromatic hydrocarbons. It can contain phenolic compounds, aromatic nitrogen (N2) bases and their alkyl derivatives, and paraffinic and olefinic hydrocarbons.
Crush – It is buckling or breaking of a section of a casting mould because of incorrect register when the mould is closed. It is an indentation in the surface of a casting because of the displacement of sand when the mould is closed. It is also the permanent localized compressive deformation. Also, it is the spalling of (normally thin) surface treated cases on gears because of the overload. This is also known as case crushing. In a split-journal bearing, it is the quantity by which a bearing half extends above the horizontal split of the bore before it is assembled
Crusher – A crusher is a multi-dimensional machine which is designed to reduce large size materials into smaller size materials. Crushers can be used to reduce the size, or change the form of waste materials so they can be more easily disposed of or recycled, or to reduce the size of a solid mix of raw materials (as in the case of ore), so that pieces of different composition can be differentiated for separation.
Crush forming – It is shaping a grinding wheel by forcing a rotating metal roll into its face so as to reproduce the desired contour.
Crushing – It is the process of transferring a force amplified by mechanical advantage through a material made of molecules which bond together more strongly, and resist deformation more, than those in the material being crushed do.
Crushing devices – These devices hold material between two parallel or tangent solid surfaces, and apply sufficient force to bring the surfaces together to generate enough energy within the material being crushed so that its molecules separate from (fracturing), or change alignment in relation to (deformation), each other.
Crushing test – It is a radial compressive test applied to tubing, sintered-metal bearings, or other similar products for determining radial crushing strength (maximum load in compression). It is also an axial compressive test for determining quality of tubing, such as soundness of weld in welded tubing.
Crush strip or bead – It is an indentation in the parting line of a pattern plate which ensures that cope and drag have good contact by producing a ridge of sand which crushes against the other surface of the mould or core.
Cryogenic air separation plant – The cryogenic air separation plant utilizes difference in boiling points of gases for their separation. It is based on the fact that the different constituent gasses of air have different boiling points and by manipulating the immediate environment in terms of temperature and pressure, the air can be separated into its components. The boiling point of oxygen at a 0.1 MPa pressure and 0 deg C is minus 182.9 deg C and that at 0.6 MPa pressure and 0 deg C is minus 160.7 deg C. The corresponding boiling points of nitrogen are minus 195.8 deg C and minus 176.6 deg C, and those for argon are minus 185.8 deg C and minus 164.6 deg C respectively. Cryogenic separation of air into its constituent gases involves various processes. Combination of these processes are needed in a cryogenic air separation plant, of which the fundamental ones are (i) air compression, (ii) air purification, (iii) heat exchanging, (iv) distillation, and (v) product compression. Cryogenic separation is most effective process when any of the three criteria need to be met namely (i) high purity oxygen is needed (higher than 99.5 %), (ii) high volumes of oxygen are needed (greater than 100 tons of oxygen / day), or (iii) high pressure oxygen is needed.
Cryogenic treatment – A cryogenic treatment is the process of treating work-pieces to cryogenic temperatures (typically around -184 deg C, or as low as −190 deg C) in order to remove residual stresses and improve wear resistance in steels and other metal alloys, such as aluminum. In addition to seeking enhanced stress relief and stabilization, or wear resistance, cryogenic treatment is also sought for its ability to improve corrosion resistance by precipitating micro-fine eta carbides, which can be measured before and after in a part using a quantimet.
Cryogenic valve – It is a valve which is capable of functioning at cryogenic temperatures.
Cryo-pump – It is a type of vacuum pump which relies on the condensation of gas molecules and atoms on internal surfaces of the pump, which are maintained at extremely low temperatures.
Crystal – It is a solid composed of atoms, ions, or molecules arranged in a pattern which is repetitive in three dimensions. It is also that form, or particle, or piece of a substance in which its atoms are distributed in one specific orderly geometrical array, called a ‘lattice’, essentially throughout the crystals directions.
Crystal analysis – It is a method for determining crystal structure, e.g., the size and shape of the unit cell and the location of all atoms within the unit cell.
Crystal-figure etching – It is the discontinuity in etching depending on crystal orientation. Distinctive sectional figures form at polished surfaces. It is closely related to dislocation etching.
Crystalline – It is that form of a substance which comprises pre-dominantly (one or more) crystals, as opposed to glassy or amorphous.
Crystalline defects – These are the deviations from a perfect three-dimensional atomic packing which are responsible for much of the structure-sensitive properties of the materials. Crystal defects can be point-defects (dislocations) or surface defects (vacancies), line defects (dislocations), or surface defects (grain boundaries).
Crystalline fracture – It is a pattern of brightly reflecting crystal facets on the fracture surface of a poly-crystalline metal, resulting from cleavage fracture of several individual crystals.
Crystallite – It is a crystalline grain not bounded by habit planes.
Crystallization – it is the separation, normally from a liquid phase on cooling, of a solid crystalline phase. It is also the progressive process in which crystals are first nucleated (started) and then grown in size within a host medium which supplies their atoms. The host can be gas, liquid, or of another crystalline form.
Crystallographic texture measurement and analysis – It is an important tool in correlating the properties of a material to its micro-structural features. It can be performed on any pol-crystalline material. Poly-crystalline materials consist of several small crystals, or grains, separated by thin boundaries assembled compactly in an aggregate. The individual crystals, or crystallites, are relatively free of defects compared to the boundary structure. Hence, a complete description of a poly-crystal is complex. On a scale of the size of the crystallites (around 1 micrometer to 1 millimeter), at least the shape, volume, and crystallographic orientation of each grain are to be prescribed. In a tensile sample of typical dimensions, up to 10 to the power 10 grains can need characterization. There is also to be an internal structure in each grain on a much finer scale (around 1 nanometer to 100 nanometer), including second phases, dislocation tangles, and point defects. These structural features also affect material behaviour considerably. Hence, complete structural characterization of the poly-crystalline body is not feasible.
Crystal orientation – It is an arrangement in space of the axes of the lattice of a crystal with respect to a chosen reference or coordinate system. It is defined by the plane (Miller) indices of the lattice plane of a crystal. In observation of an electron microscope image using a TEM, the particular crystal orientation (normally, orientation expressed by the low-order indices) is aligned to the direction of the incident electron beam.
Crystal structure – It is the arrangement of the atoms or molecules in the interior of a crystal. The unit cell of a crystal is the smallest pattern of the arrangement which can be contained in a parallelepiped, the edges of which form the ‘a’, ‘b’, and ‘c’ axes of the crystal. The three dimensional aggregation of the unit cells in the crystal forms a space lattice, or Bravais lattice’.
Crystal system – It consists of seven groups into which all crystals can be divided. These groups are named triclinic, monoclinic, orthorhombic, hexagonal, rhombohedral, tetragonal, and cubic.
Crystallized moisture – It is the chemically combined with the mineral matters in coal. It is also called decomposition moisture and is the water which is formed during thermal decomposition of the coal.
CSR – CSR is the coke strength after reaction. It gives indication of the strength of coke after being exposed to the reducing atmosphere of the blast furnace. Coke, after exposure to the high temperature and carbon di-oxide atmosphere of the coke reactivity test, is subjected to a tumbler test to determine the CSR. CSR measures the potential of the coke to break into smaller size under a high temperature carbon mono-oxide / carbon di-oxide environment which exists throughout the lower two-thirds of the blast furnace.
Cube texture – It is a texture found in wrought metals in the cubic system in which nearly all the crystal grains have a plane of the type (100) parallel or nearly parallel of the plane of working and a direction of the type [001] parallel or nearly parallel to the direction of elongation.
Cubic – It means having three mutually perpendicular axes of equal length.
Cubic plane – It is a plane perpendicular to any one of the three crystallographic axes of the cubic (isometric) system, the Miller indices are {100}.
Culvert – It is a tunnel structure constructed under roadways or railways to provide cross drainage or to take electrical or other cables from one side to other. It is totally enclosed by soil or ground. Pipe culvert, box culvert and arch culvert are the common types used under roadways and railways.
Cumulative damage – In fatigue loading, it is a measure of damage, as expressed as a fraction of life to failure, as it accumulates with the number of cycles. When the stress level is changed, the life is changed. Hence, damage accumulates as per the stress level and number of cycles spent at a given stress. The most common (but not only) model for linear cumulative damage is the Palmgren-Miner cumulative damage model [D = Sigma(ni/Ni)]. In this equation, ‘ni’ is the number of load cycles spent at a stress for which the life is ‘Ni’. Failure is assumed to occur when the damage summation becomes unity.
Cumulative erosion-time curve – It is a graph of cumulative erosion against cumulative exposure duration, normally got by periodic interruption of the erosion test and weighing of the sample. This is the primary record of an erosion test used to derive other characteristics such as incubation period, maximum erosion rate, terminal erosion rate, and the erosion rate-time curve.
Cup – It is a sheet metal part. It is the product of the first drawing operation. It is also a cylindrical part or shell closed at one end.
Cup fracture – It is also known as cup-and-cone fracture.
Cup-and-cone-fracture – It is a mixed-mode fracture, frequently seen in tensile-test samples of a ductile material, where the central portion undergoes plane-strain fracture and the surrounding region undergoes plane-stress fracture. It is called a cup fracture (or cup-and-cone fracture) since one of the mating fracture surfaces looks like a miniature cup, i.e., it has a central depressed flat-face region surrounded by a shear lip, while the other fracture surface looks like a miniature truncated cone.
Cupellation – It is the oxidation of molten lead containing gold and silver to produce lead oxide, thereby separating the precious metals from the base metal.
Cupola – It is a cylindrical vertical furnace for melting metal, especially cast iron, by having the charge come in contact with the hot fuel, normally metallurgical coke.
Cupping – It is the first step in deep drawing. It is also fracture of severely worked rods or wire where one end has the appearance of a cup and the other that of a cone.
Cupping test – It is a mechanical test used to determine the ductility and stretching properties of sheet metal. It consists of measuring the maximum part depth which can be formed before fracture. The test is typically carried out by stretching the test piece clamped at its edges into a circular die using a punch with a hemispherical end. The different cup tests are Erichsen test, Olsen ductility test, and Swift cup test.
Cure – It is the process by which paint is converted from the liquid to the solid state.
Curie (Ci) – This unit is used to measure the intensity of radioactivity in a sample of material. The Curie is equal to 37 billion disintegrations per second, which is approximately the activity of 1 gram of radium. A curie is also a quantity of any radionuclide which decays at a rate of 37 billion disintegrations per second. It is named after Marie and Pierre Curie, who discovered radium in 1898.
Curie point – It is the temperature marking the transition between ferromagnetism and para-magnetism, or between the ferroelectric phase and the paraelectric phase.
Curie temperature – It is the temperature marking the transition between ferro-magnetism and para-magnetism, or between the ferro-electric phase and the para-electric phase. It is also known as Curie point.
Curing temperature – It is the temperature to which a paint film or adhesive is subjected to cure the paint or adhesive.
Curing time – It is the period of time needed before a sand mass reaches maximum hardness.
Curl – It is an undesirable condition caused by uneven rates of absorption or evaporation of moisture, uneven rates of contraction or expansion, or internal stresses in the material. Curl is most prevalent in laminated structures where the components have differing physical properties.
Curling – It is rounding of the edge of sheet metal into a closed or partly closed loop.
Current – It is the net transfer of electric charge per unit time. It is also called electric current.
Current decay – In spot, seam, or projection welding, it is the controlled reduction of the welding current from its peak amplitude to a lower value to prevent excessively rapid cooling of the weld nugget.
Current density – It is the current flowing to or from a unit area of an electrode surface.
Current efficiency – It is the ratio of the electro-chemical equivalent current density for a specific reaction to the total applied current density. It is also the proportion of current used in a given process to accomplish a desired result. In electro-plating, it is the proportion used in depositing or dissolving metal.
Current transformers – The primary conductor of a current transformer typically has only one turn. This is not really a turn or wrap around the core but just a conductor or bus going through the ‘window’. The primary conductor never has more than a very few turns, while the secondary coil can have a large number of turns, depending upon how much the current is to be stepped down. In majority of the cases, the primary conductor of a current transformer is a single wire or bus bar, and the secondary coil is wound on a laminated magnetic core, placed around the conductor in which the current needs to be measured.
Curtain coating – It is a method of coating which can be used with low-viscosity resins or solutions, suspensions, or emulsions of resins in which the substrate to be coated is passed through and perpendicular to a freely falling liquid curtain (or waterfall). The flow rate of the falling liquid and the linear speed of the substrate passing through the curtain are coordinated in accordance with the thickness of coating desired.
Curvature of field -It is a property of a lens which causes the image of a plane to be focused into a curved surface instead of a plane.
Cushion blocks – These are normally plywood pads placed on top of precast concrete piles to eliminate spalling.
Cushion pad – It is a pad of resilient material or hardwood placed between the drive cap insert, or helmet, and drive cap adapter.
Cut – In foundry practice, cut is to recondition moulding sand by mixing on the floor with a shovel or blade-type machine. It is also to form the sprue cavity in a mould. It is also a defect in a casting resulting from erosion of the sand by metal flowing over the mould or cored surface. In lubricant technology, it is a product or fraction got by distillation within a specified temperature range.
Cut-and-fill – It is a method of stoping in which ore is removed in slices, or lifts, and then the excavation is filled with rock or other waste material (backfill), before the subsequent slice is extracted.
Cut edge – It is a mechanically sheared edge got by slitting, shearing, or blanking.
Cut-off – In casting, it is removing a casting from the sprue by refractory wheel or saw, arc-air torch, or gas torch. In metal-forming, for cut-off, a pair of blades positioned in dies or equipment (or a section of the die milled to produce the same effect as inserted blades) used to separate the forging from the bar after forging operations are completed. It is used only when forgings are produced from relatively long bars instead of from individual, precut multiples or blanks.
Cut-off wheel – It is a thin abrasive wheel for severing or slotting any material or part.
Cutting attachment – It is a device for converting an oxy-fuel gas welding torch into an oxygen cutting torch.
Cutting blow pipe – It is a non-standard term for cutting torch which is a device used in air carbon arc cutting, gas tungsten arc cutting, and plasma arc cutting for controlling the position of the electrode, to transfer current, and to control the flow of gases.
Cutting down – It is removing roughness or irregularities of a metal surface by abrasive action.
Cutting edge – It is the leading edge of a cutting tool (such as a lathe tool, drill, or milling cutter) where a line of contact is made with the work during machining.
Cutting fluid – It is a fluid used in metal cutting to improve finish, tool life, or dimensional accuracy. On being flowed over the tool and work, the fluid reduces friction, the heat generated, and tool wear, and prevents galling. It conducts the heat away from the point of generation and also serves to wash the chips away.
Cutting nozzle – It is a non-standard term for cutting tip which is the part of an oxygen cutting torch from which the gases issue.
Cutting speed – It is the linear or peripheral speed of relative motion between the tool and work-piece in the principal direction of cutting.
Cutting tip – It is that part of an oxygen cutting torch from which the gases issue.
Cutting torch – In arc cutting, it is a device used in air carbon arc cutting, gas tungsten arc cutting, and plasma arc cutting to control the position of the electrode, to transfer current, and to control the flow of gases. In oxy-fuel cutting, it is a device used for directing the preheating flame produced by the controlled combustion of fuel gases and to direct and control the cutting oxygen.
Cut-off burr – It is a projection of material left when the work-piece falls from the stock before the separating cut has been completed.
Cut wire blasting – It consists of blasting with short, cut lengths of metal wire.
Cyanic copper – It is the copper which is electro-deposited from an alkali-cyanide solution containing a complex ion made up of univalent copper and the cyanide radical.
Cyanide – It is a chemical compound which contains a C≡N functional group. This group, known as the cyano group, consists of a carbon atom triple-bonded to a nitrogen atom. In inorganic cyanides, the cyanide group is present as the cyanide anion -C≡N. This anion is extremely poisonous. Soluble salts such as sodium cyanide (NaCN) and potassium cyanide (KCN) are highly toxic. Hydrogen cyanide is produced by the combustion or pyrolysis of certain materials under oxygen-deficient conditions.
Cyanide slimes – These are finely divided metallic precipitates which are formed when precious metals are extracted from their ores using cyanide solutions.
Cyaniding – It is a case-hardening process in which a ferrous material is heated above the lower transformation temperature range in a molten salt containing cyanide to cause simultaneous absorption of carbon and nitrogen at the surface and, by diffusion, create a concentration gradient. Quench hardening completes the process.
Cycle – In fatigue, one complete sequence of values of applied load which is repeated periodically.
Cycle annealing – It is an annealing process employing a pre-determined and closely controlled time-temperature cycle to produce specific properties or micro-structures.
Cyclic corrosion test – In the cyclic corrosion test, temperature and relative humidity are varied to simulate typical wet / dry cycles like the ones taking place in natural outdoor environments. Additionally, the samples are sprinkled with a dilute NaCl solution (1 %) twice a week to induce corrosion. Though this test is still not directly representative of most real atmospheres, due to the wet / dry cycles as well as the lower chloride concentration, it is much better suited for triggering natural corrosion processes than the simple salt spray test. However, the test requires longer test times (several weeks).
Cyclic corrosion test with exposure to ultra-violet (UV) radiation – This test in addition exposes the samples to high-energy ultra-violet radiation. It is combined with water condensation, with chloride exposure and a freezing period. Organic polymers such as paints and varnishes can show degradation when exposed to sun light. This test is therefore mainly used for products with organic coatings. Apart from corrosion testing, it is also used to check the ageing effect on ultra-violet sensitive products.
Cyclic load – It is repetitive loading, as with regularly recurring stresses on a part, which sometimes leads to fatigue fracture. It is also loads which change value by following a regular repeating sequence of change.
Cyclic stress – It is the distribution of forces (also known as stresses) which change over time in a repetitive fashion, e.g., one of the large wheels used to drive an aerial lift such as a rope way. The wire cable wrapped around the wheel exerts a downward force on the wheel and the drive shaft supporting the wheel. Although the shaft, wheel, and cable move, the force remains nearly vertical relative to the ground. Hence, a point on the surface of the drive shaft undergoes tension when it is pointing towards the ground and compression when it is pointing to the sky.
Cyclodextrin – It is the cyclic degradation products of starch which contain six, seven, or eight glucose residues and have the shape of large ring molecules.
Cyclones – Cyclones are also known as centrifugal collectors. They use cyclonic separation method for the removal of the particulate matter from the exhaust gases. They remove particulate matters by causing the dirty exhaust gas stream to flow in a spiral path inside a cylindrical chamber.
Cyclone separators – Cyclone separators are gas cleaning devices which utilize the centrifugal force created by a spinning gas stream to separate particles from a gas. The gas flow is forced to follow the curved geometry of the cyclone while the inertia of particles in the flow causes them to move toward the outer wall, where they collide and are collected. In a cyclone, the particles in the spinning gas stream move progressively closer to the outer wall as they flow through the device. The gas stream can execute several complete turns as it flows from one end of the device to the other. For the design of a cyclone separator, the given gas flow rate and inner and outer radii, the length of the body of the cyclone is to ensure that a desired collection efficiency for particles of a given size be achieved. Since the length of the body of a cyclone is related through the gas flow rate to the number of turns executed by the gas stream, the design frequently consists of computing the number of turns needed to achieve specified collection efficiency.
Cylinder – It is the chamber of a piston actuator in which the piston moves.
Cylinder closure seal – It is the sealing element at the connection of the piston actuator cylinder to the yoke.
Cylindrical grinding – It is grinding the outer cylindrical surface of a rotating part.
Cylindrical land – It is the land having zero relief.
Cylinder manifold – It is a multiple header for inter-connection of gas or fluid sources with distribution points.
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