Effects of laser shock peening on microstructures and properties of 2195 Al-Li alloy

The effects of laser shock peening (LSP) on microstructures and properties of 2195 Al-Li alloy were studied in this paper. The top surface microstructure of this alloy after LSP was observed using transmission electron microscopy (TEM). The change of stress corrosion resistance after LSP was studied by slow strain rate tensile (SSRT) test. Moreover the effect of LSP on the mechanical properties was characterized by the microhardness and the residual stress test. The microstructure observation results suggested that the surface grain of this alloy was refined to the nanometer with size of 93 nm after single LSP and it can be further refined to 70 nm by 3 times LSP, the grain refinement during LSP should be considered as a dislocation evolution process based on the mechanism of rotating dynamic recrystallization (RDR). The results of mechanical properties test showed that LSP could improve the hardness and introduce the residual compressive stress in the surface of target alloy, and the 3 times LSP can further improve the properties on the base of single LSP. Furthermore, the experimental results of SSRT indicated that LSP was an effective method to improve the resistance to stress corrosion of 2195 Al-Li alloy, because the residual compressive stress and refined grains in the surface can prevent the initiation and growth of cracks, while retard the stress corrosion cracking. (C) 2018 Elsevier B.V. All rights reserved.