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

316L鋼のBWR条件下における照射硬化及びIASCC感受性に及ぼす照射誘起応力緩和の影響

三輪 幸夫; 加治 芳行  ; 塚田 隆 ; 山本 敏雄; 加藤 佳明; 米川 実 ; 松井 義典 

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

単軸引張変位下での照射行き応力緩和試験を316Lステンレス鋼に対して実施した。その試験片は4レベルの変位条件で、JMTRにて561Kで3レベルの照射量条件まで照射された。照射誘起応力緩和した後の照射硬化とIASCC感受性を、溶存酸素を含む高温水中低ひずみ速度引張試験で調べた。その結果、照射誘起応力緩和は316L鋼において照射硬化及びIASCC感受性にほとんど影響がないことがわかった。すべての試験片で、残留応力は照射量の増加とともに急速に低下し、その残留応力はIASCCを発生する応力レベルよりも低い状態であった。

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.