Ductile iron pipe is a kind of cast iron pipe, in quality requirements of cast iron pipe spherodization grade control is 1-3, that is, the spherodization rate is not less than 80%, so the mechanical properties of the material itself can be better improved, so as to have the nature of iron and the performance of steel. After annealing, ductile iron pipe microstructure is ferrite plus a small amount of pearlite, so that it has good mechanical properties, excellent anti-corrosion performance, good ductility, good sealing effect, easy installation and so on. In addition, in the medium and low pressure pipe network, ductile iron pipe has the advantages of safe operation, reliable, low damage rate, convenient construction and maintenance, excellent anti-corrosion performance and so on.