A modification of laser peening process has been carried out for forming a micro-dimple and introducing compressive residual stress in the materials and making powder deposition on the surface of substrates such as metal, polymer and wood using a metal foil.
In the present work, Q-switch pulsed YAG laser with a max. pulse energy of 650mJ as a wave length of 532nm has been used to generate ultra-high plasma pressure of around 5GPa in 8-10ns. The diameter and depth of dimple formed can be controlled by the beam spot size, max. pulse energy and thickness of metal foil in the range of 200 µｍ ～700 µｍ in diameter and in the range of 5 ～50 µｍ in depth, respectively. A trial of indirect laser peening was carried out to deposit MoS2 powders on A6061 aluminum alloy substrate to reduce the friction energy loss of piston for car engine. Process parameters such as laser intensity, type of metal foil and thickness of metal foil have been investigated to characterize this new process.