Abstract
Cavitation normally courses severe damage in hydraulic machinery such as pumps and valves, as severe impacts were produced at cavitation bubble collapses. However, cavitation impact was utilized for surface improvement in the same way as shot peening. Peening method using cavitation impacts was called "cavitation peening CP" or "cavitation shotless peening CSP", as shots were not required. The great advantage of cavitation peening was that surface roughness after peening was very smooth compared with that of shot peening, because of no solid collision. Recently, new system for cavitation has been developed to enhance cavitation impact to increase peening effects such as fatigue strength, introduction of compressive residual stress and work hardening. This research and development was partly supported by Ministry of Economy, Trade and Industry.
