Shot peening affects the fatigue crack growth performance of the material by changing the surface integrity of the material such as surface roughness

microhardness and residual stress. In this paper

two different shot peening coverage rates (100% and 300%) were used to strengthen the surface of 7B50–T7751 aluminium alloy

and the surface integrity of the strengthened specimens was characterized by roughness tester

scanning electron microscope (SEM) and X-ray diffraction (XRD). Fatigue crack growth tests were carried out on shot peened specimens and fatigue fractures were analysed to investigate the effect of different shot peening coverage rates on the rate of fatigue crack growth. The test esults show that shot peening reduces the crack growth rate of the specimen and increases the fatigue crack growth life of the specimen. In the range of 100%–300% shot peening coverage

fatigue specimens with 300% coverage showed relatively good fatigue crack growth performance

mainly due to the shot peening introducing a beneficial layer of compressive residual stress in the surface layer of the specimen and increasing the hardness of the surface layer of the specimen.