The problems that easily occured in the heavy-section ductile iron castings, such as shrinkage, dispersed shrinkage and low surface hardness, were solved by properly using graphite chills.

by means of the contrast experiment,the effect of micro-chill produced by the white castiron shot containing nodularizing elements,with the addition of 10%,on the microstructure and propor-ties of the medel specimens of heavy section ductile iron is studied,The particular function of micro-chiller in improvlng solidification behavior of heavy section ductile iron is analysed.

The of feet of St on gruphite morphology of heavy section ductile iron is studied in this paper.

The macro-fracture features of heavy section ductile iron were classified.

Computer is used for the numerical simulation of temperature field of the solidification process of heavy-section ductile iron casting.

Directing toward the heavy section ductile iron produced by Xuan hua mechanical factory of Beijing,which has the problems of spheroidization and inoculation declined and the low percent of pass,the injection is adopted instead of the tradtional method in this article.

The defects that easy occurred in heavy section ductile iron castings as well as the prevention measures were reviewed.