GRAIN REFINING OF INCONEL 718 BY ADDITION OF Ni-Nb-C ALLOY

摘要

It is well known that in the welding of the Inconel 718, microcracks are generated as a result of the dissolution of Laves phase on the grain boundary in HAZ. In this study, Ni-Nb-C alloys were employed as the additives in order to prevent the generation of microcracks by grain refining. When the melt temperature was 1623K and holding time was 5 sec, the grain size was significantly reduced to about 100 mu m and equiaxed grains were observed. The grain refining was achieved when the amount of the additives was over 0.3 mass percent.