Effect of Flap Peen Hardening on Fatigue Properties of 2024 Aluminum Alloy Prestretching Sheet

The fatigue properties of 2024 aluminum alloy prestretching sheet with an obround hole in the center before and after flap peen hardening were analyzed by group comparison method. The fatigue fracture and the residual stress of the surface of the hole wall before and after flap peen hardening were analyzed by three-dimensional digital microscope and X-ray stress tester. The results show that the median fatigue life of the 2024 aluminum alloy prestretching sheet increased by 1.727-2.728 times and 1.606-2.110 times, respectively, when loading stress were 180 MPa and 168 MPa. Flap peen hardening introduced 300 MPa residual compressive stress on the surface of aluminum alloy 2024, and the initiation region of the fatigue crack source reduced and located inside the aluminum alloy, and thus the fatigue properties of the aluminum alloy were improved.