Ductile iron is obtained by ballning and inoculation to obtain spherical graphite, effectively improving the mechanical properties of cast iron, in particular, to improve the plasticity and toughness, resulting in higher strength than carbon steel. The heavy cast iron are generally gray iron cast, gray cast iron tensile strength, plasticity and toughness is much lower than the steel, but the compressive strength and steel quite, is also commonly used cast iron in the worst mechanical properties of cast iron.