Ductile iron manhole cover is a kind of ductile iron product. Ductile iron is treated by spheroidizing and inoculating to obtain spheroidal graphite, which effectively improves the mechanical properties of cast iron, especially the plasticity and toughness, thus obtaining a higher strength than carbon steel. Ductile iron is a high-strength cast iron material developed in the 1950s. Its comprehensive performance is close to that of steel. Based on its excellent performance, it has been successfully used to cast some parts with complex forces and high requirements for strength, toughness and wear resistance. Ductile iron has rapidly developed into a widely used cast iron material second only to gray cast iron. The so-called "iron instead of steel" mainly refers to ductile iron.