Materials and Processes Seminar – Understanding Hydrogen Embrittlement in Materials

Abstract: Virtual Testing can be a game-changer in the deployment of a hydrogen energy infrastructure, enabling efficient and optimal component design, providing mechanistic predictions of material behaviour and fitness-for-service assessment, and preventing catastrophic failures. However, this highly sought ambition has long remained elusive due to the challenges associated with the complex multi-scale and multi-physics nature of hydrogen embrittlement. This work shows how those challenges can be overcome by improving our understanding of the physical phenomena at play, and by developing robust computational electro-chemo-mechanical schemes that can resolve the underlying physical processes. A comprehensive finite element framework has been developed that can: (i) quantify hydrogen uptake from both gaseous and aqueous electrolyte environments, (ii) simulate the diffusion and trapping of dissolved hydrogen, and (iii) predict the nucleation and growth of cracks, assisted by hydrogen. This has been largely facilitated by the development of two computational technologies: coupled multi-physics models and phase field modelling. Predictions can be obtained for problems of arbitrary complexity (3D, multiple cracks, etc.), at both laboratory and component scale levels. Importantly, these predictions are obtained based purely on physical parameters that can be independently measured. The potential of the framework developed will be demonstrated by addressing two case studies of significant technological interest: (1) quantifying the critical pressure at which hydrogen can be transported in natural gas pipelines without leading to structural integrity issues in welds, and (2) conducting reliable virtual hydrogen-assisted fatigue crack growth experiments for arbitrary choices of loading frequency, material, load ratio, pre-charging condition, and hydrogen pressure.