OS0723 非拡散性水素吸蔵条件下の疲労き裂進展特性に及ぼす繰返し負荷条件の影響(構造用材料の疲労挙動と寿命評価,オーガナイズドセッション)

Abstract

This paper describes the influence of cyclic loading condition and irreversible hydrogen on the fatigue crack propagation properties in a cold drawn eutectoid steel wire. Fatigue crack propagation tests were conducted for virgin samples and irreversible hydrogen charged samples. In the low ΔK_<eff> region irreversible hydrogen accelerated the fatigue crack propagation rate. However, in the high ΔK_<eff> region, the fatigue crack growth rate was not influenced by irreversible hydrogen. To elucidate the mechanism of the acceleration of the crack growth rate by irreversible hydrogen, the influence of stress cycle frequency and stress ratio was investigated. In the case of irreversible hydrogen charged sample, crack growth rate at a lower stress cycle frequency of 1 Hz was higher than that at a higher stress cycle frequency of 10 Hz. As the stress ratio become large in order of 0.1, 0.2 and 0.4, the fatigue crack growth rate increased in the irreversible hydrogen charged sample. These results were similar to the case of diffusible hydrogen.