Stress corrosion cracking susceptibility of candidate structural materials in supercritical pressurized water

Abstract The stress corrosion cracking (SCC) susceptibility in supercritical pressurized water (SCPW) was investigated for the candidate structural steels of advanced fusion and fission nuclear system, which are SUS316L austenitic steel, F82H ferritic–martensitic steel and SOC-16 oxide dispersion strengthened (ODS) ferritic steel. In order to evaluate the susceptibility to SCC with those materials, slow strain rate test (SSRT) was carried out at 773 K, under a pressure of 25 MPa of SCPW with deaerated condition. High temperature tensile test in vacuum at 773 K was also performed to compare the deformation and fracture behavior between corrosive environment of SCPW and non-corrosive environment. Although SUS316L showed a change in the fracture mode in the deaerated SCPW from an entire ductile fracture at higher strain rate to a mixed mode of ductile and brittle fracture at lower one, the fracture mode of ODS steel and F82H was not changed in the tested strain rate range. Both the IGSCC and TGSCC were observed in SUS316L. And F82H steel suffered from much severer oxidation than SUS316L and SOC-16.