steelmaking

Steelmaking is the set of industrial processes that convert iron into steel by reducing carbon and other impurities and by adjusting alloy content to achieve desired properties. It follows ironmaking, which produces pig iron; steelmaking then refines that material into a versatile metal used in countless applications.

The two dominant routes are basic oxygen steelmaking (BOS) and electric arc furnace (EAF) steelmaking. In BOS, molten pig iron is charged into a converter along with small amounts of scrap and fluxes. High-purity oxygen is blown through the molten metal, oxidizing carbon and other impurities to form a slag that captures them. The process rapidly lowers carbon content and tailors other elements; after refining, alloying elements may be added in a ladle metallurgy station, and the steel is cast into slabs, blooms, or billets.

In EAF steelmaking, electricity heats and melts scrap steel or direct reduced iron in an electrical furnace. EAFs often rely on high scrap content and can quickly switch grades, including stainless and specialty steels. Refining and alloying occur in ladle processes, followed by casting.

Most modern mills use continuous casting to solidify steel into billets, slabs, or blooms, which are then rolled and finished into products such as sheet, plate, bars, and structural sections. Open hearth and other older methods have largely been replaced by BOS and EAF routes.

Environmental aspects include energy use and emissions, with recycling of scrap playing a central role in reducing footprint. Steelmaking remains highly integrated with downstream processing and steel recycling.