Direct Observation of Stress Corrosion Cracks During SSRT Test of Stainless Steel in High Temperature Water

Direct observation of the specimen was applied on slow strain rate technique (SSRT) test in high-temperature water to investigate stress corrosion crack initiation of a stainless steel. Cracks larger than 100μm were detected by the optical behavior. The strain, at which a crack initiation was detected (crack initiation strain) decreased with decreased dissolved oxygen (DO) concentration, although the number of cracks did not have any correlation with DO concentration. The crack initiation strain was proportional to the maximum stress of the SSRT test specimen, but had no relationship with the IGSCC ratio on the fractured surface of the specimen. Thus the maximum stress was considered to be a good indicator of crack initiation.