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Safety is one of the most important issues in hydrogen economy. Earthquake sometimes gives damages to steel structures and machineries[1,2]. The components which had not been seriously damaged would still be used after the earthquake. The residual fatigue strength of those components, however, might have been decreased. The objective of this work is to clarify the effect of relatively small number of overloads and hydrogen on the residual fatigue strength of a notched component.2. Test method
2.1 Test material and test specimen
Low alloy steel designated as SCM435H in Japanese Industrial Standard was used. The chemical composition and mechanical properties are shown in Table 1 and 2, respectively. The configuration of test specimen is shown in Fig.1. It has a through-thickness single edge notch. The notch depth was 0.5mm and the root radius was 0.2mm. Test specimen was used as machined.