Ductile iron castings are one kind of globular graphite machined by spheroidization and inoculation treatments. Ductile iron castings can have better mechanical properties than the ones of iron castings effectively. Due to the well-performed plasticity and toughness endowed by ductile iron castings, they have higher strength than carbon steels. But they’re one kind of new cast iron materials with high strength, which have been developed since the 1950s. Its comprehensive properties are close to the ones of steel. It’s because of these excellent properties that ductile iron castings can be applied in some parts with strict requirements of sophisticated stress, high strength, great toughness and good wear resistance successfully. Ductile iron castings have developed to be a kind of widely-used cast iron materials only to gray iron castings.
If carbon composition among iron casting is separate out in graphite form, where graphite is shown in strip or sheet form, it’s called as gray iron casting. If shown as shapes like worms, it’s called as vermicular iron casting. If shown as flocculent shapes, it’s called as white iron casting. If shown as shapes like small balls, it’s called as ductile iron castings. Ductile iron castings has a smaller fragmented role to metals than other graphite materials. So, It can reach 70～90% of its own matrix structure, and the tensile strength can up to 120kgf/mm2.