Ductile iron is a high-strength cast iron material developed. Its comprehensive performance is close to that of steel. It is based on its excellent performance that it has been successfully used to cast some complex stress, high strength, toughness, and wear resistance. Components. Ductile iron has rapidly developed into a cast iron material that is second only to gray cast iron and is widely used. The so-called "replace steel with iron" mainly refers to ductile iron. Nodular cast iron is nodular graphite obtained through nodularization and inoculation treatment, which effectively improves the mechanical properties of cast iron, especially improves the plasticity and toughness, thereby obtaining higher strength than carbon steel.