Three various form of Iron are,
Cast Iron
Cast iron is the least pure of the irons, and contains 2.5 – 4.5% of carbon. The solidified pig iron when remelted can be cast into any shape. Thus, it is termed as the cast iron. It’s melting point is 1200°C and cannot be permanently magnetized.
Cast iron used for casting pipes, lamp post, manhole cover, railing, railway sleepers, etc. It is also used for the manufacture of steel and wrought iron.
Steel
Steel contains 0.25 – 1.5% of carbon and traces of S, P, Si and Mn. Thus, we see that the amount of carbon is steel is midway between that in the wrought iron and cast iron. It’s melting point is 1300°C – 1400°C. Steel can be permanently magnetized.
Steel generally used for railway lines, Locomotives, machinery, knives, razors, tools, surgical instruments. It is also used for making artificial magnets, magnetic needles, watch spring, agricultural implements. Alloy steels are used widely for various purposes.
Wrought Iron
It is the purest forms of the commercial iron and contains the lowest percentage of carbon, viz, 0.12 – 0.25% and some impurities like S, P, Si and Mn (not more than 0.3%). It’s melting point is 1500°C and cannot be permanently magnetized.
Wrought iron used for making wires, cores of electromagnet, chains, grills, etc.
