Pig iron is the carbon content is more than 2% of the iron carbon alloy, industrial iron carbon content is in commonly 2.5% ~ 4%, and including C, SI, Mn, S, P and other elements, is the product with writing the blast furnace smelting of iron ore. Depending on the state of carbon in cast iron, and can be divided into pig iron for steel making, casting pig iron and nodular cast iron, etc.
Precipitation of spherical graphite cast iron. Spheroidal graphite fragmentation effect to metal substrate is smaller than flake graphite, make the strength of the cast iron matrix was the strength of the 70 ~ 90%, tensile strength of up to 120 KGF/was, and good toughness. The chemical composition of ductile cast iron in addition to the iron is usually: carbon content of 3.6 ~ 3.8%, and 2.0 ~ 3.0% silicon content, manganese, phosphorus, sulfur, total amount is less than 1.5% and the amount of rare earth, magnesium nodulizing agent, etc.
Ductile iron castings are almost in all the main