Laser shock peening on fatigue crack growth behaviour of aluminium alloy

摘要

The effect of laser shock peening (LPS) in the fatigue crack growth behaviour of a 2024-T3 aluminium alloy with various notch geometries was investigated. LPS was performed under a 'confined ablation mode' using an Nd: glass laser at a laser power density of 5 GW cm~2. A black paint coating layer and water layer was used as a sacrificial and plasma confinement layer, respectively. The shock wave propagates into the material, causing the surface layer to deform plastically, and thereby, develop a residual compressive stress at the surface. The residual compressive stress as a function of depth was measured by X-ray diffraction technique. The fatigue crack initiation life and fatigue crack growth rates of an Al alloy with different preexisting notch configurations were characterized and compared with those of the unpeened material. The results clearly show that LSP is an effective surface treatment technique for suppressing the fatigue crack growth of Al alloys with various preexisting notch configurations.