The susceptibility of type AISI 304 stainless steel to transgranular and intergranular SCC in 40% MgCl2 solution at 100°C

Abstract Stress corrosion cracking (SCC) of Type 304 austenitic stainless steel in 40% MgCl 2 solution at 100°C was studied with constant potential intermediate strain rate techniques and slow strain rate techniques. Loss of HCl from the solution, during SCC tests was found to have a strong effect on crack morphology. In fresh solutions potential regions with transgranular cracks and with intergranular cracks were observed. No critical potential for SCC could be found in those solutions. In preboiled solutions only the high potential cracking, predominantly transgranular, was found. In these solutions a critical potential for SCC could be defined. Contrary to what was reported in the literature, no evidence of anodic dissolution was found during the intergranular cracking. The results are discussed from the point of view of the surface mobility SCC mechanism.