Pig iron is raw iron, the immediate product of smelting iron ore with coke and limestone in a blast furnace. Pig iron has a very high carbon content, typically 3.5%, which makes it very brittle and not useful directly as a material except for limited applications.

Specification ; C: 3.8 – 4.2%, Si 2.2 – 2.95%, Mn 0.4 – 0.8%, S: 0.02 -0.06%, P: 0.04 -- 0.08%.

Pig iron is typically poured directly out of the bottom of the blast furnace through a trough into a ladle car for transfer to the steel plant in liquid form, referred to as "hot metal." The hot metal is then charged into a steel-making vessel to produce steel, typically with an electric arc furnace or basic oxygen furnace, by burning off the excess carbon in a controlled fashion, and adjusting the alloy composition. Earlier processes for this included the Bessemer Process, open hearth furnace, finery forge and the puddling furnace