Effects of radiation-induced stress relaxation on radiation hardening and IASCC Susceptibility in type 316L stainless steel in BWR condition

Miwa, Yukio; Kaji, Yoshiyuki  ; Tsukada, Takashi ; Yamamoto, Toshio; Kato, Yoshiaki; Yonekawa, Minoru ; Matsui, Yoshinori 

Radiation-induced stress relaxation (RISR) test under uniaxial loading condition for tensile type specimens was carried out for type 316L stainless steel (SS). The specimens were irradiated in the Japan Materials Testing Reactor at 561 K to three dose levels (0.1-3 dpa) under four displacement constrained condition (prestrain range; 0.06-0.75%) in order to apply residual stress. Radiation hardening behavior and IASCC susceptibility of the RISR-tested 316L SS were examined by slow strain rate testing (SSRT) in oxygenated high temperature water. It was concluded from the SSRT results that the RISR had little influence on the radiation hardening behavior and IASCC susceptibility in the 316L SS. In all specimens, the residual stress rapidly decreased with increasing dose, and the residual stress level after irradiation was much lower than the stress level to initiate IASCC.