The effect of apparent strain rate on primary water stress corrosion cracking (PWSCC) of alloy 600(UNS N06600) and 304 stainless steel(UNS S30400) was studied at 360°C at apparent strain rate ranging from 1×10 -7 s -1 to 1×10 -5 s -1 using the slow strain rate tensile technique (SSRT). In this study, it was revealed that the PWSCC fracture mode of nickel alloy is mainly intergranular, whereas the one for the austenitic stainless steel is transgranular. The total brittle fracture decreases with increasing strain rate; however, the fraction of transgranular mode in the brittle fracture increases with increasing strain rate, i.e., the fraction of intergranular fracture increases with decreasing strain rate for both materials. The mechanism for the fracture mode change is not clear yet, however, it might be possibly explained by a similar mechanism of PWSCC for both materials, because a trend of fracture mode change for the nickel alloy resembles that of austenitic stainless steel.
Key Words: alloy 600(UNS N06600), MA600, austenitic stainless steel(UNS S30400), stress corrosion cracking, primary water, transgranular fracture, intergranular fracture, strain rate, SSRT