White Cast Iron: It is a particular variety of cast iron which shows a white fracture. The white colour is due to the fact that the carbon is in the form of carbide (known as cementite) which is the hardest constituent of iron.
This cementite is caused by quick cooling of molten iron. The white cast iron has a high tensile strength and low compressive strength. Since it is hard, therefore it can not be machined. It is used for inferior castings and in places where hard coating is required as in outer surface of car wheels.
The white cast iron is also used as a raw material in the production of malleable cast iron and wrought iron. White cast iron does not rust so much as the grey kind.