Diffusible hydrogen facilitated stress corrosion cracking in 316 stainless steel using in-situ gaseous hydrogen charging in simulated PWR environment

In this article, we introduce a novel in-situ hydrogen charging method for stress corrosion cracking (SCC) testing in a high-temperature and high-pressure water environment at 325 °C for the first time. This method effectively mitigates the interference of the electrochemical charging on the corrosion potential, and the limitation of maintaining a stable hydrogen concentration in the materials using any pre-charge methods. This approach ensures a sufficient and stable amount of diffusible hydrogen (DiffH) within the alloy matrix, which effectively maximizes the effect of diffusible hydrogen in the matrix influencing SCC at high temperatures. Post-experimental characterization reveals that DiffH has a significant impact on the oxidation behaviour near the crack tip. Notably, diffusion induced grain boundary migration (DIGM) is greatly reduced while the preferential intergranular oxidation is still present, suggesting a complex role of DiffH on SCC.