Effects of Laser Shock Peening on the Mechanical Behaviors and Microstructure of Friction Stir Processed 2A14 Aluminum Alloy

The influence of laser shock peening (LSP) on the microstructures and mechanical behaviors of the friction stir processed (FSPed) 2A14 aluminum alloy was investigated. Microhardness and tensile measurements, as well as wear test, were taken to analyze the changes in mechanical characteristics. The vibration fatigue experiments were also conducted, while the vibration fatigue life of the specimens with different treatments was compared and the fracture morphologies were observed by scanning electron microscopy. The microstructures before and after LSP were observed with electron backscattered diffraction and transmission electron microscopy. The analysis results evidenced that LSP significantly improved the mechanical properties of the FSPed specimens. Meanwhile, LSP increased the dislocation density and promoted the precipitation of the second phases on the surface layer of the FSPed 2A14 aluminum alloy, while their interactions improved the stability of the dislocation structures, which contributed to the improvement of the mechanical behaviors.