Structural materials in fusion reactors will be subjected to irradiation by energetic particles at temperatures widely ranging from liquid He to above 1000 °C. Hence, the very large irradiation creep strain at 60 °C previously reported in the ORR/ORNL pressurized tube experiment to 8 dpa is important. Computer calculations for the 20% cold-worked SUS 316 demonstrated the transient nature of this radiation-induced creep, caused by the overwhelming flux of excess interstitial atoms lasting nearly one year at 60 °C where the diffusivity of vacancies is very low. In order to confirm such a transient nature, continuous creep measurement under irradiation is necessary and was carried out using 17 MeV protons. Development of very significant creep strain, much larger than that at 300 °C, and steadily decreasing creep rate were observed at 60 °C as the calculation predicted. A significant influence of the dynamic irradiation effect at 60 °C on fatigue fracture was also observed.
Nagakawa, J., Murase, Y., Yamamoto, N., & Fukuzawa, T. (2000). Irradiation creep at 60 °C in SUS 316 and its impact on fatigue fracture. Journal of Nuclear Materials, 283–287(PART I), 391–395. https://doi.org/10.1016/S0022-3115(00)00078-7