Computational Modeling of Hydrogen-Assisted Fatigue Crack Growth in Pipeline Steels

In this work we further develop a model to predict hydrogen-assisted fatigue crack growth in steel pipelines and pressure vessels. This model is implemented by finite element code, which uses an elastic-plastic constitutive model in conjunction with a hydrogen diffusion model to predict the deformation and concentration of hydrogen around a fatigue crack tip. The hydrogen concentration around the crack tip is used to inform our fatigue crack growth model and account for the effect of hydrogen embrittlement. We first use our model to predict the fatigue crack growth of X100 pipeline steel at different levels of applied hydrogen pressure. The simulated results are within a factor of ± 2 of the experimental X100 results.