Tensile properties of irradiated modified 316 stainless steel (PNC316) at slow strain rates

Yano, Yasuhide  ; Miyazawa, Takeshi   ; Tanno, Takashi  ; Akasaka, Naoaki; Yoshitake, Tsunemitsu ; Kaito, Takeji ; Otsuka, Satoshi   

The effects of strain rate on tensile properties of irradiated modified 316 stainless steel (PNC316) claddings were investigated. PNC316 claddings were irradiated at the experimental fast reactor Joyo using CRT402 control rod assembly at 400C up to 25 dpa. Post-irradiation ring tensile tests were carried out at strain rates of 3.310, 3.310 and 3.310 s at a test temperature of 350C. The results showed no obvious dependence of all strain rates on tensile properties, although a slight decrease in total elongation was observed at the slowest strain rate of 3.310 s. In addition, only a part of fracture surface at the slowest strain rate showed intergranular type region in the inner surface area, although the grain boundary separation occurred on inner surfaces near the fracture region at all strain rates. It is suggested that presence of a high content of helium near the inner surfaces would be related to the fracture behavior.