Role of Lubrication during the Process of Metal Working Feb15

Role of Lubrication during the Process of Metal Working...

Role of Lubrication during the Process of Metal Working For understanding the role of lubrication during the processes of metal working, it is important to know the tribology of the lubrication. Tribology consists of boundary friction, which is associated with almost all operations of the metal working. It is caused by the relative movement of two adjacent surfaces under pressure. During the metal working processes, the relative movement between rolls and work piece is improved by the surface speed differential of the rolls Friction Friction plays an important role during metal working process. It is defined as the resistance to relative motion between two bodies in contact. It is an energy dissipating process, causing the temperature at the interface to rise and, if excessive, can result in surface damage. It also influences the deformation taking place in the metal working process. As per the earliest theories, friction is the result of interlocking two rough surfaces sliding along each other. Friction is actually brought on by a large number of variables, such as load, speed, temperature, the materials involved in the sliding pair, and the various effects of fluids and gases at the interface. Most commonly accepted theory of friction is based on the resulting adhesion between the severities of the contacting bodies. It has been seen that regardless of how smooth the surfaces are, they contact each other at only a fraction of their apparent area of contact. Thus, the load during the process of metalworking is supported with few severities in contact. Hence, the normal stress at the severity junctions is high. Under light loads, the contact stresses can only be elastic. However, as the load increases to some of the levels involved in the metal working process, elastic deformation of the severities...

PERED Technology for Direct Reduced Iron Production Jan18

PERED Technology for Direct Reduced Iron Production...

PERED Technology for Direct Reduced Iron Production PERED technology is also known as ‘Persian Reduction’ technology. It is the direct reduction technology invented and patented by ‘Mines and Metals Engineering GmbH’ in 2007. The PERED direct reduction process converts iron oxides, in the form of pellets or lump ore, to highly reduced product suitable for steel making. The reduction of iron oxide takes place without its melting with the help of reducing gases in solid state in a vertical shaft furnace. This technology improves the process of direct reduction for the production of direct reduced iron (DRI). The process is a gas based direct reduction process which has been developed by a team of specialists having experience in different areas of the direct reduction process to ensure that all the flows of different processes are taken care in the main process to obtain optimum and efficient results. The most popular gas used for reduction is reformed natural gas though other gases such as Corex gas and coke oven gas etc. can also be used. PERED technology lowers capital cost, water consumption, maintenance cost, and energy consumption. In PERED, the reduction process takes place at a lesser temperature due to the improved cooling methods and reduced pollutant gas emissions. With less heat, more homogeneous reducing gas, more controllable pellet feed and use of centrifugal compressors, PERED requires less water, electricity and gas to operate, alongside less operational and maintenance expenditure. Output from the PERED direct reduction plants can be in the form of (i) cold direct reduced iron (CDRI), hot briquetted iron (HBI), combination of CDRI/HBI, HBI/hot direct reduced iron (HDRI), and CDRI/HDRI. PERED technology is an improved energy efficient technology and hence economizes energy and resources. It makes optimum use of energy and raw materials...

Mechanical Processes for Descaling of Steel Sep08

Mechanical Processes for Descaling of Steel...

Mechanical Processes for Descaling of Steel Scale is the product of oxidation which takes place during hot rolling. The oxidation and scale formation of steel is an unavoidable phenomenon during the process of hot rolling which involve reheating of steel in a reheating furnace, multi-pass hot rolling and air-cooling in the inter-pass delay times and after rolling. Scale formed during the heating of steel to rolling temperatures in the reheating furnace is known as primary scale. This primary scale is removed before hot rolling. It is usually done for producing steel products with high surface quality and for reducing roll wear. However, secondary scale continues to form on the descaled steel surface during the inter-pass delay time in the roughing and intermediate rolling mills. The colour of primary mill scale is generally bluish black while that of the secondary scale is blue.  The secondary scale gives the steel an appearance which is similar to that of a lacquer coating finish and is often mistaken for a blue coloured primer. The primary scale is composed of three well defined layers of iron oxides. Adjacent to the steel is the thickest layer consisting of wustite having an approximate composition of FeO. The intermediate layer consists of magnetite (Fe3O4) while the outermost layer is hematite (Fe2O3). The thicknesses of these layers depend on several factors linked to the rolling of the steel and the availability of oxygen at the steel surface. The layer at the surface of the steel is richest in oxygen and constitutes 0.5 % to 2 % of scale thickness. The layer at the metal surface is richest in iron and constitutes about 85 % of the scale thickness. The intermediate layer of scale constitutes around 13 % to 14.5 % of scale thickness....

Limestone – Its Processing and Application in Iron and Steel Industry Jul07

Limestone – Its Processing and Application in Iron and Steel Industry...

Limestone – Its Processing and Application in Iron and Steel Industry Limestone is a naturally occurring and abundant sedimentary rock consisting of high levels of calcium carbonate (CaCO3) in the form of the mineral calcite. Some limestones may contain small percentage of magnesium carbonate (MgCO3). These limestones are known as dolomitic limestones. Limestone is also a very important industrial mineral. Its chemical properties make it a valuable mineral for a wide range of industrial/manufacturing uses. Limestone is also one of the vital raw materials used in production of iron and steel. Limestone, by definition, is a rock that contains at least 50 % of CaCO3 in the form of calcite by weight. There can be small particles of quartz (silica), feldspar (alumino-silicates), clay minerals, pyrite (iron sulphide), siderite (iron carbonate), and other minerals associated with the limestone. All limestones contain at least a few percent other materials. The Impurities in limestone can consists of silica (SiO2), alumina (Al2O3), iron oxide (Fe2O3), sulphur (as sulphides or sulphates), phosphorus (P2O5), potash (K2O), and soda (Na2O). Silica and alumina are the main impurities of limestone. The limestone which is used in ironmaking is required to contain at least 85 % of calcium carbonate and a low percentage of alumina. Similarly limestone which is used for steelmaking is required to contain at least 92 % of calcium carbonate and a very low percent of impurities especially the silica percentage. The main uses of limestone in iron and steel industry are (i) as a fluxing material, and (ii) other usage which consists of desulphurizing agent, coating of moulds of pig casting machine, neutralizing of acidic water, water treatment, waste water(effluent) treatment, flue gas treatment, and sludge and sewage treatment. It is also a component of synthetic slag. Limestone is...

Dolomite – Its Processing and Application in Iron and Steel Industry Jun28

Dolomite – Its Processing and Application in Iron and Steel Industry...

Dolomite – Its Processing and Application in Iron and Steel Industry Dolomite is an anhydrous carbonate mineral. It is a double carbonate of calcium and magnesium (CaCO3.MgCO3). It is one of the important raw materials used in production of iron and steel. Dolomite contains theoretically 54.35 % of CaCO3 and 45.65 % of MgCO3 or 30.41 % of CaO, 21.86 % of MgO, and 47.73 % of CO2. However, in nature, dolomite is not available in this exact proportion. Hence generally the rock containing in the range of 40 % to 45 % of MgCO3 is usually called dolomite. The main uses of dolomite in iron and steel industry are (i) as a fluxing material (ii) for protection of refractory lining, and (iii) as a refractory raw material. Dolomite in iron and steel industry is normally used in three forms. These are (i) raw dolomite which is also the natural form of dolomite, (ii) calcined dolomite, and (iii) sintered dolomite. When dolomite is used as a fluxing material then it is used as either raw dolomite or calcined dolomite. When dolomite is used for the protection of refractories, it is used in calcined form and when dolomite is being used as a refractory raw material, it is used in the form of sintered dolomite. The uses and form of dolomite in iron and steel industry is shown in Fig 1. Fig 1 Uses and form of dolomite in iron and steel industry Processing of dolomite Dolomite after its mining has to undergo several processing before it can be used in various processes. The basic processes in the production of dolomite are (i) quarrying of raw dolomite, (ii) preparing mined dolomite for its use by crushing and sizing, (iii) calcining of raw dolomite, (iv) processing...

Rolling of Steel in a Modern Long Product Rolling Mill Jun19

Rolling of Steel in a Modern Long Product Rolling Mill...

Rolling of Steel in a Modern Long Product Rolling Mill Long product is a common name for (i) reinforcement steel bars, (ii) shaped steel bar products such as rounds, flats, squares, and hexagon etc., (iii) sectional products such as angles (equal and unequal), channels, beams, tees, and special profiles etc., and (iv) wire rods. Mills which roll long products are known as long product mills. Based on the product being rolled these mills are called, merchant bar mill, bar and rod mill, light section mill, rebar mill, light merchant mill, special bar quality (SBQ) mill, and wire rod mill etc. The product range of these mills usually consists of those shaped and sectional products whose cross-section is smaller than the cross section of the products rolled in medium and heavy section rolling mills. Wire rod mills produces steel wire rods of diameters 5 mm to 12.5 mm in coil form with the weight of the coil upto 2.5 tons. The qualities of steels being rolled in these mills can range from low carbon, mild steel, medium carbon, high carbon, and micro and low alloyed steels. The design of the long product rolling mill is required to provide right solutions for the required performance requirements which include high speed production, microstructure qualities of the product, and shortest changeover time from one product to other product etc. Large amount of flexibility is available in modern long products rolling mills. These mills are normally continuous mills consisting of three sets of rolling stands namely (i) roughing group of stands, (ii) intermediate group of stands and (iii) finishing group of stands. The input material for these mills is normally billet. A billet mill can be combined with the long product rolling mill through a roller hearth furnace in...