Numerical Investigation of the Influence of Nonmetallic Inclusions on the Local Hydrogen Concentration under Consideration of Residual Stress Fields

Abstract

Hydrogen as an energy carrier is politically supported and essential for the planned energy turnaround, but requires infrastructure for transport and storage of hydrogen on a large scale, which in turn requires the development of steels resistant to hydrogen‐induced damage. Since the experimental characterization of local hydrogen concentration is nearly impossible, but microstructure level effects are significant for damage initiation, it becomes essential to further develop accompanying numerical evaluation methods. These have to be able to quantitatively describe the effect of nonmetallic inclusions on the local hydrogen concentration as the detrimental effect of nonmetallic inclusions governs the resistance against hydrogen‐induced cracking. To capture this influence, the modeling approaches available in the literature are extended and made usable for tetrahedral elements. Validation is performed using numerical studies with specimens of different stress states. Submodels are exposed to a virtual cooling and then to a hydrogen loading. Based on the resulting residual stress fields, the local hydrogen concentrations around nonmetallic inclusions with different chemical compositions and geometry are investigated and evaluated. Herein, it can be shown that especially the hydrostatic stress has a large influence on the development of the local hydrogen concentration and that the influence is particularly strong for Al2O3‐inclusions.