1. Ductile iron. It is obtained by spheroidizing the molten iron of gray cast iron, and the precipitated graphite is spherical, which is referred to as ductile iron for short. All or most of the carbon exists as spherical graphite in a free state, and the fracture is silver gray. It has higher strength, better toughness and plasticity than ordinary gray cast iron. The brand name is represented by “QT” followed by two sets of numbers, for example: QT45-5 (the first set of numbers represents the lowest tensile strength, the second set of numbers represents the lowest elongation). Used in the manufacture of internal combustion engines, auto parts and agricultural machinery.

2. Vermicular graphite iron. The grey cast iron molten iron is obtained by creeping treatment, and the precipitated graphite is in the form of a worm. The mechanical properties are similar to nodular cast iron, and the casting performance is between gray cast iron and nodular cast iron. Used to manufacture auto parts.

3. Alloy cast iron parts. Ordinary cast iron is obtained by adding appropriate amount of alloying elements (such as silicon, manganese, phosphorus, nickel, chromium, molybdenum, copper, aluminum, boron, vanadium, tin, etc.). The alloy element changes the matrix structure of the cast iron, so that it has the corresponding characteristics of heat resistance, wear resistance, corrosion resistance, low temperature resistance or non-magnetic properties. Used to manufacture parts for mines, chemical machinery, instruments and meters.