The fatigue crack growth behavior of hydrogenated 9Cr-1Mo steel: An experimental and numerical study

Abstract

This research investigates the fatigue crack evolution in P91 steel through experiments and extended finite element method (XFEM) simulation for as-received and hydrogenated conditions. Hydrogen pre-charging is performed using a constant current electrochemical method in 1 M sulfuric acid solution. The study compares the experimental fatigue crack growth rate (FCGR) of hydrogenated and as-received conditions and employs an XFEM simulation to replicate FCGR. The results of the experiments reveal an increased FCGR in hydrogenated specimens. Fracture surface analysis confirms the co-occurrence of the “hydrogen-enhanced localized plasticity” (HELP) and “hydrogen-enhanced decohesion” (HEDE) mechanism (HELP+HEDE, HEDE>HELP). The simulation results closely align with the experimental findings, validating the model's accuracy. Consequently, these findings are the basis for proposing a damage tolerance approach-based numerical algorithm. This algorithm allows the prediction of component integrity by considering a known crack length. Furthermore, fracture toughness (KIQ) was experimentally evaluated to enhance the understanding of the material's mechanical properties.