Effect of laser shock peening and annealing temperatures on stability of AA2195 alloy near-surface microstructure

Abstract

The thermal stability of surface microstructure as well as mechanical property induced by laser shock peening (LSP) in AA2195 alloy was investigated in the present work. Samples of the AA2195 alloy were firstly LSPed in once or three times and then annealed at 250, 300 and 350 °C for 1 h, respectively. The surface microstructures of LSPed and annealed samples were investigated by transmission electron microscopy (TEM), and the thermal stability of the mechanical properties was characterized by the changes of the residual stresses and microhardness at the top surface layer. Results showed that the critical temperatures of the sample with 3-times LSP leading to the notable grain growth and changes of mechanical properties were 350 °C and 300 °C respectively, and the corresponding temperatures of the sample with 1-time LSP were 300 °C and 250 °C respectively. Precipitates (eg. T1) in the surface layer of AA2195 alloy were dissolved after LSP, and the thermal stability of the structure and mechanical property was improved by the secondary precipitation of T1 phase during following annealing. The experimental results exhibited that the thermal stability of the sample with 3-times LSP was better than that of the 1-time LSPed one, which indicated that multiple times LSP enable benefit of the stability of structure and mechanical property of AA2195 alloy.