管道环焊缝由于成分偏析、应力集中等缺陷，在含氢环境中更易发生氢损伤，威胁管道安全运行。以X70管线钢环焊缝作为研究对象，采用气相原位充氢的方法，对焊条电弧焊+药芯焊丝电弧焊和熔化极气体保护焊2种焊接工艺得到的焊接接头(分别记为1号、2号)分别开展空气、1 MPa氢气、2 MPa氢气环境下的断裂韧性特征值测试，研究试样断裂韧性特征值及裂纹扩展微观形貌变化规律。结果表明，X70管材1号环焊缝为低强匹配，2号环焊缝为高强匹配，相同环境中1号环焊缝断裂韧性优于2号环焊缝；试验环境的氢气压力对2种环焊缝断裂韧性特征值影响不大，环焊缝力学性能对断裂韧性特征值的影响大于氢气的影响。在含氢环境中，2种环焊缝断裂韧性试样裂纹扩展起始阶段均出现脆性转变，其中2号环焊缝裂纹扩展过程解理形貌面积更大，氢脆敏感性相较于1号环焊缝高。不同焊接工艺得到的焊接接头强度越高，在含氢环境氢脆敏感性越高。

Girth welds in pipelines are more susceptible to hydrogen-induced damage under hydrogen-containing environments due to defects such as compositional segregation and stress concentration, posing a threat to the safe operation of pipelines. X70 pipeline steel girth welds were investigated in this study. Two types of welded joints were prepared using shielded metal arc welding combined with flux-cored arc welding(defined as Weld 1), and gas metal arc welding(defined as Weld 2), respectively. In-situ gas-phase hydrogen charging was employed, and fracture toughness characteristic values of the welded joints were tested under three environments: air, 1 MPa hydrogen, and 2 MPa hydrogen. The changes in fracture toughness and the micromorphology of crack propagation were investigated. Results showed that Weld 1 exhibited low-strength matching, while Weld 2 exhibited high-strength matching. Under the same environmental conditions, the fracture toughness of Weld 1 was superior to that of Weld 2. The hydrogen pressure in the testing environment had a limited effect on the fracture toughness values of both welds, whereas the mechanical properties of the welds had a more significant influence than the hydrogen environment. In hydrogen-containing conditions, both welds exhibited brittle fracture initiation behavior. Weld 2 showed a larger area of cleavage fracture morphology during crack propagation, indicating a higher sensitivity to hydrogen embrittlement compared to Weld 1. Results indicated that welded joints with higher strength produced by different welding processes were more sensitive to hydrogen embrittlement in hydrogen-containing environments.