The high temperature three point bend testing of proton irradiated 316L stainless steel and Mod 9Cr–1Mo

Abstract The predicted operating conditions for a lead–bismuth eutectic target to be used in an accelerator driven system for the Advanced Fuel Cycle Initiative span a temperature range of 300–600 °C while being irradiated by a high energy (∼600 MeV) proton beam. Such spallation conditions lead to high displacement rates coupled with high accumulation rates of helium and hydrogen up to 150 appm/dpa. Some candidate materials for these applications include Mod9Cr–1Mo and 316L stainless steel. To investigate the effect of irradiation on these materials, the mechanical properties are being measured through three point bend testing on Mod 9Cr–1Mo and 316L at 25, 250, 350 and 500 °C after irradiation in a high energy proton beam (500–800 MeV) to a dose of 9.8 dpa at temperatures from 200 to 320 °C. By comparing measurements made in bending to tensile measurements measured on identically irradiated materials, a measurement of 0.2% offset yield stress was obtained from 0.05% offset yield stress measured in three point bend testing. Yield stress increased by more than a factor of two after irradiation to 9.8 dpa. Observation of the outer fiber surface of 316L showed very localized deformation when tested after irradiation at 70 °C and deformation on multiple slip systems when tested after irradiation at 250–320 °C.