Effects of hydrogen charging on the corrosion behavior and hydrogen embrittlement of 7xxx Al Alloys: An integrated experimental and multiscale simulation study

This work presents a novel integrated approach combining in-situ and pre-charging electrochemical hydrogen charging (EHC) methods with multiscale simulations to unravel the synergistic effects of hydrogen on the corrosion and mechanical degradation of 7xxx Al alloys. The in-situ EHC coupon exhibited enhanced mechanical performance and reduced HE susceptibility (10.3 %) compared to the EHC 4 h and EHC 12 h coupons. A coupled mechanical-hydrogen diffusion finite element model (FEM) and density functional theory (DFT) calculations were developed to predict hydrogen distribution and its interaction with microstructural defects. Fractography and simulations identified a synergistic HE mechanism where hydrogen-enhanced localized plasticity (HELP) dominated at low hydrogen concentrations, facilitating dislocation mobility, while hydrogen-enhanced decohesion (HEDE) prevailed at higher concentrations, promoting intergranular fracture. This study establishes a framework for the coexistence and transition between HELP and HEDE mechanisms, governed by hydrogen concentration and local stress states, offering actionable insights for designing hydrogen-resistant Al alloys in marine and energy storage applications.