Development of Laser Cavitation Peening Using a Normal-Oscillation Nd:YAG Laser

The impact induced by cavitation bubble collapse can be utilized for mechanical surface treatment to improve fatigue properties of metals including additive manufactured metallic materials. A peening method using cavitation impact induced by a pulsed laser is called “laser cavitation peening (LCP)”. Normally, a Q-switched Nd:YAG laser, whose pulse width is a few nanoseconds, is used for LCP, which improves the fatigue strength. The problem with LCP is that the processing time is too slow. If a laser pulse whose pulse width is a few hundred microseconds can be utilized for LCP, the repetition frequency can be increased drastically using other types of laser systems such as a fiber laser. In the present paper, in order to reveal the possibility of LCP using a pulsed laser width of a few hundred microseconds, the use of LCP with a normal-oscillation Nd:YAG laser (pulse width ≈ 200 us) was investigated. It is demonstrated that LCP with the normal-oscillation Nd:YAG laser produced curvature in an aluminum alloy plate.