Ductile iron manhole cover is a type of ductile iron product. Ductile iron obtains spherical graphite through spheroidization and inoculation treatment, effectively improving the mechanical properties of cast iron, especially improving plasticity and toughness, resulting in higher strength than carbon steel. Ductile iron is a high-strength cast iron material developed in the 1950s, with comprehensive properties similar to steel. Based on its excellent performance, it has been successfully used to cast some parts with complex stress, high requirements for strength, toughness, and wear resistance. Ductile iron has rapidly developed into a widely used cast iron material, second only to gray iron. The so-called "replacing steel with iron" mainly refers to ductile iron.