Forms | Classification of Iron

Based on the varying percentages of carbon, iron is broadly classified into the following:

1. Pig iron:

Pig iron is the product of smelting iron ore. It contains up to 5% carbon. This carbon content is quite high and it makes the pig iron hard and brittle, and thus difficult to work with.

Consequently, pig iron is not very useful in technology for fabrication purposes. However, pig iron is refined to produce other forms of iron such as cast iron, wrought iron, steel, etc.

2. Cast iron:

This is produced by refining pig iron in a furnace called cupola. It contains 2% to 5% of carbon.

The pig iron scraps and some limestone are put in the furnace and burnt together with coke fire. The molten pig iron is then put into moulds to form either white cast iron (in the form of iron carbide) or grey cast iron (in the form of graphite)

Cast iron is brittle, and can easily break if given a hard blow.