Evaluation of Fracture Properties of Two Metallic Materials under Hydrogen Gas Conditions by Using XFEM

Interest in hydrogen energy is increasing due to its eco-friendliness and ease of use. Research is being conducted to produce and use hydrogen in various fields such as hydrogen vehicles and nuclear power plants. However, considering the purity requirements and the need for containment, experiments with hydrogen have several constraints, such as accounting for the charging and purging time. In this study, the effects of hydrogen gas on the fracture properties of T6 heat-treated 6061 aluminum alloy (Al6061-T6) and Chromium-molybdenum steel (SA372) were investigated using the extended finite element method (XFEM). First, numerical analyses for smooth and notched slow strain rate tensile test specimens under air and hydrogen gas conditions were conducted using a multi-island genetic algorithm and XFEM to derive true stress-strain data and damage parameters of the two materials based on experimental results. Second, the fracture resistance curves of 1/2T-compact tension (CT) specimens made of SA372 steel were determined by crack growth analyses using the calibrated parameters. The estimated J(Q) values were compared with those from experiments to validate the method, of which differences were less than 20%. Finally, the fracture properties of Al6061-T6 alloy were predicted using the same method with 1/2T-CT specimens.