Using an indentation test to evaluate the effect of cavitation peening on the invasion of the surface of austenitic stainless steel by hydrogen

In order to demonstrate the effect that the compressive residual stress introduced by cavitation peening has on suppressing the invasion of the surface of steel by hydrogen, we examined the surface after hydrogen charging using a spherical indenter. It was demonstrated that hydrogen considerably hardens the surface of austenitic stainless steel by 35% and that the surface hardening induced by hydrogen was reduced with increasing compressive residual stress introduced by cavitation peening. Moreover, the surface hardness was restored to its initial state after two weeks due to hydrogen desorption from the charged surface. This shows that the hardening was caused by the invasion of the surface by hydrogen and that the introduction of compressive residual stress suppresses it.

► Suppression of the hydrogen invasion into surface by cavitation peening was demonstrated.
► To verify the hydrogen-induced surface hardening, an indentation test was conducted.
► The not-treated specimen hardened by 35% by hydrogen.
► The rate of hardening induced by hydrogen decreased with increase in compressive residual stress.