The alpha form is magnetic, but when transformed into the beta form, the magnetism disappears although the lattice remains unchanged. The relations of these forms are peculiar. Pig iron is an alloy containing about 3 percent carbon with varying amounts of S , Si , Mn , and P . Iron is hard, brittle, fairly fusible, and is used to produce other alloys, including steel. Carbon steel is an alloy of iron with small amounts of Mn, S, P, and Si.
Alloy steels are carbon steels with other additives such as nickel , chromium , vanadium , etc.
Iron is a cheap, abundant, useful, and important metal.