Ductile iron manhole covers are a type of ductile iron product. Ductile iron is obtained by spheroidizing and孕育 treatment, resulting in spherical graphite, which effectively enhances the mechanical properties of cast iron, particularly its plasticity and toughness, thereby achieving a strength higher than that of carbon steel. Ductile iron is a high-strength cast iron material developed in the 1950s, with comprehensive properties close to those of steel. It is precisely due to its excellent performance that it has been successfully used for casting parts with complex stress conditions, high requirements for strength, toughness, and wear resistance. Ductile iron has rapidly become the second most widely used cast iron material, after gray cast iron, with the term "iron instead of steel" primarily referring to ductile iron.

Ductile iron manhole covers are generally divided into circular and square shapes. In urban road management, circular covers are commonly used as they are less likely to tilt, thereby providing better safety for pedestrians and vehicles. The preference for circular covers stems from the fact that every diameter passing through the center of a circle is of equal length. This ensures that if a vehicle were to lift the cover, the diameter would always be slightly wider than the diameter of the manhole below, preventing the cover from falling into the hole.