微小疲労き裂の下限界近傍進展特性に及ぼす侵入水素の影響

低合金鋼, 炭素鋼, 析出強化型耐熱鋼A286についての検討

抄録

Hydrogen is considered to be a possible energy source in the coming future. However, it has been recognized that hydrogen has a detrimental effect on the fatigue strength of metal. The fatigue crack growth characteristic is an important property for the integrity assessment of hydrogen utilization machine. In this report, the effect of absorbed hydrogen on the fatigue crack propagation characteristic in the near threshold regime was studied using low alloy steel, carbon steels and heat resistant alloy A286. Especially in this study, very short pre-cracked specimen as small as 0.03 mm deep was used. As a result, materials with Vickers hardness higher than 300 were susceptible to absorbed hydrogen irrespective of alloy system. Fatigue crack propagation was accelerated and the ΔK_th was lowered about 25%. No remarkable change was observed in materials with hardness lower than 200.