A study of shot peening and spinning rolling on fatigue of Al 7075 alloy samples

Surface mechanical strengthening is an effective way to improve the fatigue performance, among which surface rolling has been vastly utilized for its significant enhancement in fatigue strength. However, traditional rolling process is only suitable for components with rotational symmetry, limiting its application. Herein, a newly developed technology named "spinning rolling (SR)" was developed to strengthen the surfaces of platy components. A common Al alloy, 7075, was selected for verifying the effect. It is found that compared with the most popular technology, shot peening (SP), SR can provide deeper and higher residual stress, lower surface roughness, and comparable hardening layer, and consequently, significantly higher fatigue lives. Accordingly, there is a transition in the fatigue crack source from point-like to line-like, confirming a strong crack propagation resistance along depth direction. This study indicates the advantages of the SR technology, providing a greater resistance against fatigue damage of platy components. We developed a new surface strengthening technology-spinning rolling (SR), which has wider applicability and better fatigue life extension effect. The fatigue lives of 7075 aluminum alloy plates processed by SR are highly improved by even one order of magnitude at the same stress amplitude. There is a transition in the fatigue crack source from point-like to line-like, confirming a strong crack propagation resistance along depth direction due to SR.