Ferrous metals include steel, pig iron, cast iron, iron alloys, manganese, chromium, vanadium, titanium, etc. Steel: A general term for iron-carbon alloys with a carbon content between 0.02% and 2.11% by mass. The chemical composition of steel can vary greatly, and steel containing only carbon elements is called carbon steel (carbon steel) or ordinary steel. Pig iron: It is an iron-carbon alloy with a carbon content of more than 2%. The carbon content of industrial pig iron is generally 2.11%-4.3%, and it contains Si, Mn, S, P and other elements. It is a product of iron ore smelted by blast furnace.