Question

State the use of:
(a) cast iron
(b) wrought iron
(c) mild steel
(d) hard steel

Answer 1

Hint: Cast iron and wrought iron both are susceptible to corrosion and hence are exposed to oxygen. Mild steel and hard steel differs in the carbon content which is responsible for their hardness.

Complete step by step answer:
(A) Cast iron is the most common iron which contains other elements like carbon, silicon and manganese. As it contains carbon the tensile strength is reduced but the compressive strength is not affected. The cast iron is of four types, grey, white, malleable and ductile. Each of these varies in the percentages of the elements present. They are used in applications where high stiffness, high heat capacity and high thermal conductivity are required. It has a wide variety of usage everywhere. Grey cast iron is used for cylinder blocks, gearbox cases, disk brake rotors and cookware. White cast iron is used for slurry pumps, lifter bars, cement mixers, crushers, pipe fittings and pump impellers. Malleable cast iron is used for electrical fittings and equipment, pipe fittings, farm equipment, and machine parts. Ductile cast iron is used for vehicle gears and suspension components and pumps and hydraulic parts.
(B) Wrought iron is iron composed of a very small amount of carbon. It is soft, ductile, magnetic, high elastic and high tensile strength, magnetic, malleable and becomes stronger when it is worked to make new substances. It is used in fences, gates, chains, roof cresting, lamps, grilles, porches and verandas and hardware.
(C) Mild steel also known as low carbon steel is low priced. The exhibit various properties like high tensile strength, good ductility and weldability, magnetic, are oxidized if not coated. It is widely used in furniture and decorations, wire, nails, fencing, structural steel, cars, beams etc.
(D) Hard steel contains high amounts of carbon and chromium carbide. As a result the wear resistance of this steel is increased. They exhibit properties like corrosion resistance, abrasion resistance and durability. It is used for making tools and machine parts.

Note:
In general cast iron cannot be molded like wrought iron. They generally break with applied pressure. Mild steel is cheaper and softer than hard steel due to less carbon content.