INFLUENCE OF RARE EARTH ON GRAIN BOUNDARY CRACKING OF CAST STEEL Ni9

The grain boundary cracking of the cast steel Ni9 seems to be mainly related tothe segregation of contaminantes H, S and P along boundaries. An addition of rare earth mayeliminate the segregation of these contaminantes along grain boundaries and improve the bind-ing force among boundaries, so as to reduce remarkably the grain boundary cracking.