Numerical Evaluations Coupled With Micro-Macro Characteristics of Stainless Steel Against Hydrogen Environments

Abstract The scope of hydrogen applications has been expanded into various fields, including energy storage, transportation, nuclear fusion, and nuclear thermal propulsion etc. Even though stainless steels have been considered as candidate material to ensure sustainability and durability under such as high pressure or liqufied hydrogen environment. Hydrogen-induced damage mechanisms such as hydrogen-enhanced decohesion, and Hydrogen-Enhanced Localized Plasticity etc. related complex stress-hydrogen infiltration needs to be systemically managed. In the present study, ultrasonic shot peening treatment was performed as a preventive surface treatment, and various experiments and finite element analysises were carried out to evaluate material characteristic for microstructural refinement and damage resistance. Firstly, ultrasonic shot peening simulations corresponding to microstructural refinement based on experimental results were performed to calibrate strain energy correlation. The effective depth against hydrogen charging in the microstructure was also evaluated by coupling the energy data with information on grain refinement. Subsequently, a damage model coupled with degration effect due to temperature and hydrogen concentration were employed by reflecting dominant hydrogen induced damage. Then, damage behaviors were analyzed under stress concentration-hydrogen conditions and validated using corresponding mechanical test data. Finally, the complementary applicability of numerical methods was also discussed prior to crack growth evaluation for fracture properties and integrity assessment of structure under hydrogen environment.