Ductile iron manhole cover is a kind of ductile iron products. Nodular cast iron obtains nodular graphite through spheroidization and inoculation treatment, which effectively improves the mechanical properties of cast iron, especially improves plasticity and toughness, so as to obtain higher strength than carbon steel. Ductile iron is a high-strength cast iron material whose comprehensive performance is close to that of steel. It is based on its excellent performance that it has been successfully used to cast some parts with complex stress and high requirements for strength, toughness and wear resistance. 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 "substituting iron for steel" mainly refers to ductile iron.