Material hardness and hardness testing...

Material hardness and hardness testing Material hardness is the property of the material which enables it to resist plastic deformation, usually by penetration or by indentation. The term of hardness is also referred to stiffness or temper, or to resistance to bending, scratching, abrasion, or cutting. It is the property of a material, which gives it the ability to resist being permanently, deformed when a load is applied. The greater the hardness of the material, the greater the resistance it has to deformation. Hardness has been variously defined as resistance to local penetration, scratching, machining, wear or abrasion, and yielding. The multiplicity of definitions, and corresponding multiplicity of hardness measuring instruments, together with the lack of a fundamental definition, indicates that hardness may not be a fundamental property of a material, but rather a composite one including yield strength, work hardening, true tensile strength, modulus of elasticity, and others. In mineralogy, hardness is normally described as the resistance of a material to being scratched by another material. The ability of materials to resist scratching by another material can be ranked by referring to the Mohs scale which assesses relative hardness of the materials. In metallurgy hardness is defined as the ability of a material to resist plastic deformation. It is sometimes known as indentation hardness which is the resistance of a material to indentation. The usual type of hardness test is where a pointed or rounded indenter is pressed into a surface of the material under a substantially static load. Hardness measurement can be carried out at macro scale, micro scale or nano scale according to the forces applied and displacements obtained. Measurement of the macro hardness of the material is a quick and simple method of finding mechanical property data for the bulk...

Cast Steels and Steel Castings...

Cast Steels and Steel Castings Steel casting is a specialized form of casting involving various types of steels. Steel castings are used when cast irons cannot deliver enough strength or shock resistance. A steel casting is the product formed by pouring liquid steel into a mould cavity. The liquid steel cools and solidifies in the mould cavity and is then removed for cleaning. Heat treatment may be needed to meet desired properties. This process provides the near net shape and mechanical properties required for meeting the specifications. The differences between steel castings and wrought steels are principally in the method of production. In the case of wrought steel cast ingots, slabs, blooms, and billets are mechanically worked to produce flat, sectional or tubular products. However, steel castings are produced in the final product (near net shape product) form without any intermediate mechanical working. The making of a steel casting is a long and complex process. A large investment in capital equipment is required for the melting of steel, manufacturing of cores and moulds and the cleaning and heat treating of castings. Additional major investments for support equipment and facilities are required for sand reclamation systems, dust collection devices and bulk material handling systems etc. Steel castings are used for vitally important components in the mining, railways, automotive, construction, military, and various industries including oil and gas industries. Steel castings are specified for applications which require weldability, abrasion resistance, high strength, low and high temperature service and corrosion resistance. Though there are large numbers of steel foundries, yet due to the diversity of market requirements such as size, tolerances, chemistry, volume, etc., a single foundry cannot serve all of the market and each foundry tends to specialize in a portion of the total market. Some of the specialized...

Comparison of Steel with Aluminum...

Comparison of Steel with Aluminum Steel is an alloy of iron and other elements, primarily carbon. It is most commonly produced by reduction of iron ore. Carbon, the most common alloying material in steel, acts as a hardening agent, preventing any dislocations within the iron atom crystal lattice from separating and sliding past each other thus making steel more durable. By varying the amount of alloying elements and the form of their presence in the steel, one can control qualities such as hardness, ductility, and tensile strength of steel. Though, steel has been known to be around since 4,000 years ago, it was not widely produced until the 17th century. Its mass production started due to the introduction of the Bessemer process during 1850s. This process made steel production cheaper, efficient and easier. Production of steel is a two stage process. First iron is produced by reduction of iron ore. This iron is then converted into steel by oxidizing the impurities. (Fig 1) Fig 1 Production process of steel Steel is widely used in construction and other applications because of its high tensile strength and low cost. Iron is the basic component of steel. Composition of steel mainly consists of iron and other elements such as carbon, manganese, silicon, phosphorus, sulphur, and alloying elements. A large number of elements in wide ranging percentages are used for the purpose of alloying of steels. Variations in chemical composition of steels are responsible for a great variety of steel grades and steel properties. Each element that is added to the basic steel composition has some effect on the properties of the steel and how that steel reacts to the processes of working and fabrication of steels. The chemical composition of steel also determines the behaviour of steel in...

Structural Steel – Preferred Material for Construction...

Structural Steel – Preferred Material for Construction Structural steel is not just a material which has only the technical competence. It has many other qualities that make it the preferred material for architects, designers and engineers. It is economical and provides great mechanical functionality; it permits the design of structures which are graceful, light and airy; it streamlines construction site processes; and it offers rapid execution. A major advantage, however, is the infinite freedom for creation which it provides to the architects, designers and engineers. The combination of structural steel with different materials lends themselves to rich and varied types of construction. When combined with glass, structural steel makes fabulous use of light and space. Structural steel is the material ‘par excellence’ when it comes to inventing new structures and forms. All solutions are possible, from the very simplest to the most challenging. Structural steel can be used for small buildings as well as large structures, for routine construction projects, and those subject to complex urban constraints. No other material is used to make structures which are so thin, light and airy. Forms can be created using different structural effects and envelopes with pure or finely sculpted curves. Architects, designers and engineers can give free reign to their imagination and creativity with structural steels. Structural steel is a standard construction material made from specific steel grades and is available in standard cross sectional shapes. This steel exhibits desirable physical properties such as strength, uniformity of properties, light weight and ease of use etc. This makes it one of the most versatile structural materials in use. Major applications for this steel is in high rise and tall multi-storey buildings, industrial buildings, towers, tunnels, bridges, road barriers, and industrial structures etc. Within the overall architectural concept,...

Steel – The Most Used Material...

Steel – The Most Used Material If people are asked to name the critical components needed for sustaining everyday life, the obvious answer will include the elements like water, food, and air. If people are asked to name necessities of life then the answer will include food, clothing and housing. No one will ever include steel in the list of the critical and necessary items. However, steel is the most common material that one comes into contact with every moment, all the day and every day. There is hardly any object that people use today which does not contain steel or which is not created with equipment made of steel. In fact, today it is hard to imagine a life without the use of steel in some shape or form.  One has to just think of what would be missing in his everyday life if there is no steel. Without steel the very existence of man would be prehistoric. Today the society is wholly dependent on steel and the steel is an indispensable part of the human existence. It adds to the quality of life, is essential to ensure the safety of water and food supply, provides energy efficiency, ensures warmth, transports energy, connects people all around the world and makes the lives of the people secure. One cannot imagine today what his life would be, if there is no steel.  Steel is environmentally sound and utterly reliable. Tried and tested yet always new and exciting, steel is everywhere, making the lives of people easier and livelier. Steel is the measure of progress of modern civilization. Steel began its ascent in the Iron Age and is now both visibly and invisibly omnipresent in everyone’s everyday life. Most household items contain steel and people entrust...