Laser peening without coating on aluminum alloy Al-6061-T6 using low energy Nd:YAG laser

The present study investigates the effect of laser peening without coating on aluminum alloy Al-6061-T6 with a 300 mJ infrared laser. The surface topography, microstructure, surface topography, surface residual stress and micro-hardness of peened and unpeened surfaces were studied. The study shows that laser peening without coating can significantly improve surface compressive stress and micro-hardness with trivial increase in surface roughness. Microstructure evaluation confirmed there was no near surface solidification after LPwC.

► Laser peening without coating improved the compressive residual stress to 270%.
► No near surface solidification due to direct laser ablation.
► Micro-hardness showed a maximum of 10 HV increase than unpeened specimen.
► The peening effect pertain up to 0.7 mm from the surface.
► Laser peened surface exhibited X-ray peak broadening.