The effect of microstructural features on the hydrogen induced cracking (HIC) susceptibility of two API 5L X65 pipeline steels were investigated by cathodic charging, hydrogen permeation and hydrogen microprint experiments. Microstructural evaluation after hydrogen charging revealed cracks at the mid-thickness (segregation zone) of both plates. However, more severe cracks were observed in the plate with higher dislocation density and residual stresses. The plate with lower plastic strain and more {111}-oriented grains had less severe cracks. Inclusions found along the crack path, comprising of Si-enriched oxides and carbides contributed to the initiation and propagation of cracks. The variation of the trapping behaviour and hydrogen diffusion through the plates were examined. The results confirmed that a higher ratio of reversible to irreversible traps contributes to increasing HIC severity in steels. Additionally, hydrogen transport through the steels was most prominent along the grain boundaries, indicating the importance of grain boundary character to HIC.

通过阴极装料，氢渗透和氢显微照片实验研究了微观结构特征对两种API 5L X65管线钢的氢诱导开裂（HIC）敏感性的影响。充氢后的显微组织评估表明，两块板的中间厚度（偏析区）均出现裂纹。然而，在板中观察到更严重的裂纹，具有更高的位错密度和残余应力。具有较低塑性应变和更多{111}取向晶粒的板的裂纹较少。沿裂纹路径发现的夹杂物，包括富硅氧化物和碳化物，有助于裂纹的产生和扩展。检查了俘获行为和通过板的氢扩散的变化。结果证实，较高的可逆陷阱与不可逆陷阱的比例有助于提高钢中的HIC严重性。另外，通过钢的氢沿晶界的传输最显着，表明晶界特征对HIC的重要性。