Effects of Surface Grinding on Hardness Distribution and Residual Stress in Low Carbon Austenitic Stainless Steel SUS316L

It has been reported that stress corrosion cracking (SCC) occurs in core shrouds made with a low carbon austenitic stainless steel, SUS316L, in-service. The cracks were initiated at grain interiors in surface layer and propagated with trans-granular (TG) mode at a distance, and then the mode was changed into inter-granular (IG) type. It was also reported that hardness in surface region near cracks was higher than those in internal regions, which was attributed to surface grinding treatment. Sensitization due to formation of chromium carbides at grain boundaries was not observed. It seems to be difficult to interpret the TGSCC on the basis of the conventional mechanism of SCC. Especially, effects of surface grinding on SCC phenomenon are not sufficiently clarified. Therefore, in the present study, residual stress and strain induced by grinding have been focused and measured by means of relatively new techniques.