Hydrogen charging effects on the oxidation of Alloy 690 with different cold rolling degrees in high temperature water environment

The effects of H charging on Alloy 690 were investigated under different cold rolling degrees in high-temperature water. The study examined changes in the thickness of the inner oxide layer under different cold rolling degrees. During the cold rolling process, Cr diffusivity demonstrated minimal variation as a result of the competing effects between increased dislocation density and the transition from high-angle grain boundaries (HAGBs) to low angle grain boundaries (LAGBs). The interaction between H and the microstructure during the cold rolling process influences the oxidation of Alloy 690. The presence of interstitial H atoms in dislocations and grain boundaries inhibits the outward diffusion of Cr³⁺ while simultaneously promoting oxidation. However, with increased cold rolling and microband formation, many dislocations are generated, offering new paths for Cr element diffusion to the surface.