A coupled cohesive modeling approach for predicting fractures in low alloy steel under high-pressure hydrogen gas

Hydrogen-induced fractures usually occur in low alloy steel under the influences of stress concentration and high-pressure hydrogen gas. The purpose of this study was to predict the hydrogen-induced fracture behavior of low alloy steel under a high-pressure hydrogen gas environment. The hydrogen-sensitive cohesive model was used for the prediction of crack propagation, which took into account the influence of high-pressure hydrogen gas. The coupling model between hydrogen diffusion and plastic deformation was also applied by using UMAT and UMATHT subroutines. Disk pressure tests were performed on 4130X steel with different hydrogen pressure rise rates to demonstrate the coupled cohesive modeling approach. The hydrogen-induced fracture behaviors of the 4130X steel disk predicted by the proposed approach showed good agreement with experimental results. Numerical results indicated that hydrogen accumulated at the anchorage of the disk and reduced the maximum cohesive stress with the enhancement of localized plastic deformation. Therefore, the crack growth rate of the disk increased under a high-pressure hydrogen gas environment with relatively low maximum cohesive stress and low fracture energy. (C) 2020 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.

Automated summary

This study aimed to predict the hydrogen-induced fracture behavior of low alloy steel under a high-pressure hydrogen gas environment. The proposed approach using coupled cohesive modeling showed good agreement with experimental results for 4130X steel disk. The accumulation of hydrogen at the anchorage of the disk reduced the maximum cohesive stress and increased the crack growth rate under a high-pressure hydrogen gas environment.