Relationship on Cavitation Shotless Peening between Residual Stress and Pressure Distribution of Cavitation Impact

摘要

Impacts induced by cavitation at bubble collapse can utilize to surface modification as same way as shot peening. This method is called as cavitation shotless peening (CSP), as shots are not required. As the mechanism of impact is completely different between shot peening and CSP, CSP has different effects from shot peening. For example, in case of introduction of compressive residual stress by shot peening, the compressive residual stress has a maximum at certain depth. Thus, in order to increase the compressive residual at the surface, multi-stage shot peening using different size of shot was required. However, CSP can introduce maximum compressive residual stress at the surface. This sort of effect depends on the pressure distribution of the impacts. In the present paper, the pressure distribution associated with introduction of compressive residual stress was investigated by measuring the plastic deformation pit on different hardness specimens.