Hydrogen embrittlement has been recognized as one of major degradation mechanisms causing the decrease of ductility and fracture toughness of several kinds of materials. In accordance with the demand for hydrogen fuels, it becomes more important to ensure safety of relevant facilities like pressure vessels, storage tanks and so on. The objective of this study is to examine fracture resistance of American Petroleum Institute (API)-X70 steel under highly pressurized hydrogen gaseous condition. The extended finite element method (XFEM) was adopted to predict J-R curves via a crack growth simulation approach. At first, preliminary analyses for SM490A carbon steel were carried out to demonstrate applicability of the XFEM, of which result was comparable to test data within 14 %. Subsequently, iterative numerical analyses were conducted to calibrate appropriate damage parameters for the API-X70 steel by using notched round bar specimens. Finally, crack growth simulations of 1T-compact tension (CT) specimens were performed adopting the calibrated parameters. JIC values determined from predicted J-R curves were compared with 1/2T-CT CTOD test data and relevant constraint effect was discussed.

氢脆已被认为是导致多种材料延展性和断裂韧性下降的主要降解机制之一。根据对氢燃料的需求，确保压力容器、储罐等相关设施的安全变得更加重要。本研究的目的是检验美国石油学会 (API)-X70 钢在高压氢气状态下的抗断裂性。采用扩展有限元法 (XFEM) 预测JR曲线通过裂纹扩展模拟方法。首先，对 SM490A 碳钢进行了初步分析，以证明 XFEM 的适用性，其结果与测试数据的可比性在 14% 以内。随后，通过使用缺口圆棒试样，进行迭代数值分析以校准 API-X70 钢的适当损伤参数。最后，采用校准参数对 1T 压缩拉伸 (CT) 试样进行裂纹扩展模拟。将根据预测的JR曲线确定的 JIC 值与 1/2T-CT CTOD 测试数据进行比较，并讨论了相关的约束效果。