주철
Cast iron comes in many types, depending on the carbon-content. However, they are usually divided into grey and white cast iron, depending on the form that the carbides take. In grey cast iron, the carbon is mainly in the form of graphite, but in white cast iron, the carbon is usually in the form of cementite. Grey cast iron consists mainly of the microstructure called pearlite, mixed with graphite and sometimes ferrite. Grey cast iron is usually used as-cast, with its properties being determined by its composition.