On the basis of carbon content, iron mainly can be divided into two categories.
a. Cast Iron: It is the most impure form of iron. It contains 2-5% carbon and trace amount of other impurities. Solidified cast iron cannot be reshaped and welded. It is highly brittle and can be permanently magnetized. When Cast iron is solidified, it slightly expands. So, it has wide ranges of application like casting of stoves, pipes, toys, radiators etc. Cast iron is converted into steel by using various methods.
b. Wrought Iron: It is the purest form of iron. It contains about 0.12-0.25% of carbon and other impurities. It is manufactured from the cast iron by puddling process. It is highly malleable and ductile. Wrought iron cannot be magnetized. Wrought iron can be welded and reshaped again and again by melting. It is resistant towards corrosion. Due to its non-rusting property, it is expansive than cast iron. It is used to make chains, bolts, electromagnets, dynamos, wires etc.
c. Steel: Steel is the intermediate product between wrought iron and cast iron. It contains 0.2-2.5% carbon and other impurities. The hardness of steel vary with the amount of carbon content in it. Steel is malleable and ductile. Steel has wide ranges of application in the modern world.