The effect of laser shock processing on the microstructures and properties of 2060 Al[sbnd]Li alloys

Abstract

The microstructures, mechanical properties and corrosion resistance of 2060 AL-Li alloy subjected to laser shock peening (LSP) with power densities of 3, 4 and 5 GW·cm−2 were investigated comprehensively. Microhardness, residual stress, wear resistance and fatigue life were tested on LSP alloys to analyze the mechanical properties and the corrosion behavior was investigated by electrochemical test. X-ray diffraction (XRD) and field emission transmission electron microscopy (FE-TEM) were used to investigate the surface microstructure evolution. The results show that LSP leads to a high magnitude of surface compressive residual stress and a significant increase of dislocation density near the surface in the plastic deformation layer. Additionally, with the increase of laser power density, the microhardness, compressive residual stress and surface roughness increase, while the friction coefficient and wear rate decrease compared to pristine alloy. The fatigue life of the sample with a laser power density of 4 GW·cm−2 reaches the highest value of 6.00 × 104 times, approximately twice that of the pristine sample (2.98 × 104 times), which is mainly attributed to the surface residual compressive stress, high density dislocations and surface hardening owing to the LSP. The corrosion resistance of the LSP alloys modestly decreases in a 3.5% NaCl solution compared with pristine alloy, which mainly ascribes to the increase of surface roughness.