Effects of implanted hydrogen on fatigue behavior of F82H under irradiation

Abstract In situ stress-controlled fatigue tests were performed for F82H steels under 17 MeV proton irradiation with an energy degrader at 60 °C. The energy degrader enhanced the hydrogen implantation rate from 2.6 × 10 −6 to 1.3 × 10 −3 appm/s at a dose rate of 1.1 × 10 −7 dpa/s. Although number of fatigue cycles to fracture ( N F ) under irradiation without the degrader increased to about 2 times N F for the unirradiated condition, only a slight increase of N F (1.2 times) was detected for the irradiation with the degrader. The surface morphology of the fracture surfaces was similar for both in situ irradiation fatigue specimens with and without the degrader. A modified technique of fractographic surface topography analysis (FRASTA) demonstrated rapid crack propagation under irradiation with the degrader. Substantial levels of implanted hydrogen play a role in reducing the effect of irradiation on fatigue behavior based on the interaction between radiation-induced defect clusters and moving dislocations.