Abstract
The impact caused by cavitation bubble collapse can be applied to the peening of the metallic material due to introducing compressive stress and plastic deformation at the surface. The improvement of fatigue strength of the metallic material by cavitation impact is almost as same as that of conventional shot peening. However, it has been reported that both thickness and residual stress level of the modified layer by the cavitation impact are smaller than those of the shot peening. In the present report, in order to clarify the formation of the plastic deformation area caused by cavitation impact, a visualization using the fry etching method was conducted. It is elucidated that the shape of plastic deformation area beneath the pit is different from that of the dent caused by Hertz contact using spherical indenter. In the case of sufficient treatment using cavitation impact the uneven boundary between the modified layer and the substrate was observed.
