Abstract:
Fatigue life and fatigue crack growth tests were performed on X60 pipeline steel in a gaseous environment containing 10% (volume fraction) H
2 at a total pressure of 12 MPa. The fatigue crack initiation and propagation behaviors of X60 pipeline steel in a hydrogen environment were investigated, and the effects of hydrogen pre-charging and loading frequency were examined. The results show that hydrogen reduced the fatigue crack propagation life of X60 pipeline steel under a loading frequency of 1 Hz, but its effect on crack initiation life was not significant. Meanwhile, pre-charging with hydrogen for 10 h decreased both the crack initiation life and the crack propagation life under the same loading frequency. In the 10% hydrogen environment, the fatigue life of X60 pipeline steel was close under loading frequencies of 1 Hz and 2 Hz. However, when the loading frequency was reduced to 0.5 Hz, the crack initiation life decreased obviously, leading to a corresponding reduction in fatigue life. In the 10% hydrogen environment, the fatigue crack propagation rate was 9.56 times higher than that in the hydrogen free environment, and hydrogen reduced the threshold stress intensity factor range (Δ
Kth) required for crack propagation.