Enhancement of Surface Property by Low-Energy Laser Peening without Protective Coating

Laser peening without protective coating (LPwC) has been applied to metallic materials using low energy pulses of a Q-switched and frequency-doubled Nd:YAG laser. Compressive residual stresses of several hundred megapascals were imparted on the surface of the materials. Redistribution of the residual stress in the top surface due to thermal loading was evaluated non-destructively by synchrotron radiation of SPring-8. Accelerating stress corrosion cracking (SCC) tests showed that LPwC prohibited SCC of sensitized materials. LPwC largely prolonged the fatigue lives of titanium alloys, aluminum alloys and austenitic stainless steels.