Hydrogen-Enhanced Cavitation Erosion Resistance of 316L Stainless Steel

It has been established that hydrogen diffusion can significantly influence the mechanical response of metallic materials under various loading conditions. This phenomenon is particularly evident in reducing the ability for macroscopic plastic deformation. The formation and collapse of bubbles inside a fluid, i.e., cavitation, near a solid surface, generates one of the most complex loading scenarios. The characteristics of localized, high-velocity, and cyclic loading inherent to this process may lead to material removal from the surface, a phenomenon known as cavitation erosion. The mechanical properties of the metal surface, affected by hydrogen, may alter the resistance against erosion wear under cyclic loading conditions during cavitation. In this research, 316L stainless steel samples were electrochemically charged in H2SO4 to assess the effect of diffused hydrogen on mechanical behavior, as determined by tensile and micro-indentation testing. The cavitation erosion experiments were conducted on hydrogen-charged and uncharged samples in an ultrasonic cavitation test rig. The findings showed that hydrogen diffusion resulted in a significant reduction of up to 80% in cavitation erosion damage after 5 h of testing compared to the uncharged sample. After seven days of storage, however, the cavitation erosion damage of the hydrogen-charged specimens returned to a level comparable to that of the uncharged specimens, indicating that the beneficial effect of hydrogen on cavitation erosion resistance is reversible. Following short-term cavitation exposure, notable plastic deformation was observed on the eroded surfaces of the uncharged specimens, particularly as raised grain boundaries and slip bands. In contrast, the surfaces of the hydrogen-charged specimens predominantly retained their integrity, suggesting an increased resistance to plastic deformation following hydrogen charging.