Black metal (Black metals) — iron and alloys based on it (steels, ferroalloys, cast iron). Ferrous metals make up more than 90% of the total volume of metals used in industry. The main element that gives iron alloys various properties is carbon. Ferrous metals are divided into: Cast irons - iron-carbon alloys with a carbon content of more than 2.14% (up to 6% in some cast irons). Cast irons are divided into white, gray and malleable. Steels are alloys of iron and carbon with a carbon content of less than 2.14%. low carbon (less than 0.25%), carbon (0.25-0.6%), high carbon (more than 0.6%). Cast iron and steel, in addition to carbon, also contain other components: alloys: for the production of cast iron and steels with the necessary properties - corrosion resistance, elasticity, malleability, heat resistance; alloying components include silicon, aluminum, manganese, molybdenum, copper, nickel, chromium, vanadium, tungsten, etc.; harmful impurities: sulfur, phosphorus, arsenic, oxygen, nitrogen.