Effects of laser shock peening on fatigue crack growth rate and fracture properties of AA2524 aluminum alloy

In order to prolong the service life of aircraft skin made from AA2524, the effects of laser shock peening (LSP) on fatigue crack growth (FCG) rate and fracture toughness ( K c ) of AA2524 were investigated. Multiple LSP treatment was performed on compact tension (CT) specimen from single side and double sides. The surface integrity was measured with Vickers hardness tester, X-ray diffractometer and confocal laser scanning microscope, respectively. FCG rate test and fracture toughness test under plane stress were carried out after LSP treatment. The microstructure features of cross-sections were observed with scanning electron microscope. The results showed that the micro-hardness and residual stress of CT specimens were increased dramatically after LSP treatment. Compared to the base metal (BM), the fatigue life was prolonged by 2.4 times and fracture toughness was increased by 22% after multiple LSP.