Spheroidal graphite cast iron. The grey cast iron is obtained by spheroidizing, and the precipitated graphite is spherical, referred to as nodular iron. Carbon in all or most of the free form of spherical graphite exists, the fracture of silver gray. Compared with ordinary gray iron, it has higher strength, better toughness and plasticity. The brand is marked by "two" numbers followed by "QT", such as QT45-5 (the first group numbers indicate the minimum tensile strength, and the second group numbers indicate the minimum elongation). Used in the manufacture of internal combustion engines, automotive parts and agricultural machinery and so on.
Malleable iron。 Obtained by annealing treatment of white cast iron, the graphite is a group of flocculent distribution, referred to as ductile iron. Its properties are uniform, wear resistance, good plasticity and toughness. Used to produce parts of complex shape and capable of withstanding strong dynamic loads.
White cast iron. The content of carbon and silicon is low, carbon mainly exists in cementite form, and the fracture is silvery white. It is easy to produce shrinkage and crack when it is solidified. High hardness, brittleness, and can not withstand impact load. Number of blanks used as malleable iron and production of wear-resistant parts.
Grey cast iron. The higher carbon content (2.7% ~ 4%), carbon exists mainly flake graphite morphology, the fracture was grey, referred to as gray iron. The melting point is low (1145~1250 DEG C), the shrinkage is small, the compressive strength and hardness are close to carbon steel, and the damping property is good. Because the flake graphite exists, the abrasion resistance is good. The casting performance and cutting process are better. Used for manufacturing machine tool bed, cylinder, box and other structural parts. Its brand is "HT", followed by two sets of figures. For example: HT20-40 (the first number indicates the minimum tensile strength, and the second group numbers indicate the minimum flexural strength).
