Cast iron is an iron-carbon alloy with a carbon content of more than 2.11%. It is obtained by high-temperature melting and casting of steel such as industrial pig iron and scrap steel and its alloy materials. In addition to Fe, carbon in other cast irons is precipitated in the form of graphite. If the precipitated graphite is in the form of a strip, the cast iron is called gray cast iron or gray cast iron, the cast iron in the form of a worm is called vermicular cast iron, and the cast iron in the form of a floc is called white cast iron or code iron, and is spherical. Cast iron is called ductile iron.
The chemical composition of ductile iron except iron is usually: carbon content of 3.0 to 4.0%, silicon content of 1.8 to 3.2%, total manganese, phosphorus and sulfur content of not more than 3.0% and appropriate amount of spheroidized elements such as rare earth and magnesium.