(Chemical symbol: Fe3C) A carbide of iron which occurs as a micro-constituent of steel and cast iron. It is the normal form of carbon which occurs in steel. Cementite may occur interspersed with ferrite, or in a free form as a network, or in plates. On prolonged heating, particularly if there has been distortion of the steel, it is possible to get decomposition of cementite into free carbon and iron. See CAST IRON, Hard Spots and METALLURGY.
