抄録
The cyclic stress-strain behavior and the crack closure behavior were investigated to study the mechanism of fatigue strength reduction caused by absorbed hydrogen using SUS304 and SUS316L. Solution heat-treated and pre-strained austenitic stainless steels were used. Strain measurement test to study the bulk behavior of cyclic plasticity and fatigue crack propagation test were done. There was no significant effect of absorbed hydrogen on the bulk behavior of cyclic plasticity. Fatigue crack propagation rate was accelerated by hydrogen especially in the case of R = -1. The crack opening stress of hydrogen charged material was lowered than that of uncharged material. The acceleration could be explained by the increase of ΔK_<eff>. The enhancement of fatigue damage by absorbed hydrogen is not caused by changing the macroscopic stress-stain behavior but by a microscopic phenomenon such as crack closure.
