Scrap chugunny, Dnepropetrovsk region.

Cast iron is an alloy of iron with carbon (and other elements), in which the carbon content is not less than 2.14% (the point of the limiting solubility of carbon in austenite is present on the diagram), and alloys with a carbon content of less than 2.14% are called steel. Carbon gives iron alloys hardness, reducing plasticity and viscosity. Carbon in cast iron can be contained in the form of cementite and graphite. Depending on the form of graphite and the amount of cementite, white, gray, ductile, and high-strength cast iron are distinguished. Cast irons contain permanent impurities (Si, Mn, S, P), and in some cases — also alloying elements (Cr, Ni, V, Al and others). As a rule, cast iron is brittle.