In the study, hydrogen effects on the fracture toughness of an API X90 pipeline steel are investigated considering specimen thickness effects. It is found that the embrittlement of fracture increases with thickness for the hydrogenated specimens. The fracture toughness of hydrogen-free specimens are about 2.9, 5.2 and 11.6 times larger than the hydrogenated ones for B/W = 0.5, 1 and 2, respectively. Digital image correlation (DIC) measurement indicates that as the specimen thickness increases, hydrogen deteriorates drastically the plasticity in the vicinity of the crack tip. A remarkably low dislocation density is observed, indicating hydrogen atom has great influence on the cohesive energy, rather than the dislocation pile-ups. Finally, it is concluded that hydrogen enhanced decohesion (HEDE) mechanism is responsible for the high hydrogen sensitivity to the specimen thickness.

在研究中，考虑了试样厚度的影响，研究了氢对API X90管线钢的断裂韧性的影响。发现氢化试样的断裂脆度随厚度增加而增加。无氢试样的断裂韧度是B / W试样氢化断裂试样的断裂韧性的2.9倍，5.2倍和11.6倍 分别为0.5、1和2。数字图像相关性（DIC）测量表明，随着样品厚度的增加，氢在裂纹尖端附近的可塑性急剧下降。观察到非常低的位错密度，表明氢原子对内聚能有很大的影响，而不是位错堆积。最后，得出的结论是氢增强脱粘（HEDE）机理是氢对样品厚度的高敏感性的原因。