Effect of Multiple Laser Shock Peening without Coating on Al-2024-O Alloy for Automotive Applications

Abstract

The present work discusses the influence of surface compressive residual stress induced by multiple laser shock peening without coating process using low energy Nd: YAG laser with the fundamental wavelength. Laser shock peening without absorbent coating (LSPwC) was employed to Al-2024 in order to improve its surface microstructure and mechanical properties. The compressive residual stress measurements are accomplished according to X-ray diffraction sin 2 Ψ method. The surface morphology and roughness analysis were carried out using atomic force microscope and roughness profilometer respectively. Also, the microstructure analysis was performed using an optical microscope and scanning electron microscope. The Vickers micro-hardness revealed the improvement of surface and sub-surface hardness after multiple laser shock peening without coating process using low energy laser. Introduction. Laser shock peening is a recently developed advanced surface modification technology which has been very effective in improving strength, wear, hardness, roughness and corrosion resistance of metallic materials. It is cold deformation process where pulses hit the surface through high power intensity and shock waves are generated. Laser shock peening (LSP) utilizes high energy laser pulses to impact the surface of the metallic material covered with a transparent confinement layer (usually water).