Ductile iron pipes are a type of cast iron pipe. Quality standards require the spheroidizing grade of cast iron pipes to be controlled at 1-3 levels (spheroidizing rate >80%), thereby significantly improving the material's mechanical properties, combining the essence of iron with the performance of steel. After annealing, the microstructure of ductile iron pipes consists of ferrite plus a small amount of pearlite, featuring excellent mechanical properties, corrosion resistance, and good ductility. They also provide excellent sealing and are easy to install, mainly used for municipal and industrial enterprises in water supply, gas transmission, and oil transportation.

On the ferrite and pearlite matrix, a certain number of spherical graphite balls are distributed. The proportion of ferrite and pearlite in the matrix structure varies depending on the nominal diameter and the requirements for elongation. For small diameters, the pearlite proportion is generally not more than 20%, while for large diameters, it is typically controlled around 25%.