Abstract
Although cavitation impacts normally cause severe damage in hydraulic machinery such as pumps and valves, they can be used for peening in the same way of shot peening. The peening method using cavitation impacts is named as cavitation peening. At the cavitation peening, cavitation was generated by injecting a high-speed waterjet into a water filled chamber. This sort ofjet is called as a cavitating jet. In the case of the cavitating jet, aggressivity of the cavitation impact is increasing with scale and / or injection pressure, i.e., velocity at the nozzle of the jet In order to establish cavitation peening, the effect of the scale and the velocity of the cavitating jet on the cavitation peening was investigated. The residual stress of stainless steel JIS316L introduced by the cavitating jet was evaluated at various injection pressure and nozzle size. It was revealed that the introduced compressive residual stress was increased with the nozzle size from 0.35 mm to 2 mm. The compressive residual was nearly constant when the injection pressure increased from 100 MPa to 300 MPa. At constant jet power, compressive residual stress introduced by the large size cavitating jet at low injection pressure was larger than that of small cavitating jet at high injection pressure.
