Effects of aging state on the low-cycle fatigue properties of 2024 aluminum alloy

To reveal the effects of aging state on the low-cycle fatigue (LCF) performance of 2024 Al alloy, LCF experiments were conducted on the 2024 Al alloy with three aging states (underaged (UA), peak-aging (PA) and overaged (OA)), respectively. It is found that under the total strain amplitude and plastic strain amplitude control, the Al alloy at UA and OA states exhibits higher LCF lives than that at PA state, respectively. For a more comprehensive evaluation, a hysteretic energy model with W0 as the fatigue damage capacity and β as the fatigue damage resisting exponent was used, which also shows the advantages of the OA states. This is because although the OA state has lower fatigue damage capacity W0 for the inferior strength-plasticity combination compared to the UA state, it has higher fatigue damage resistance exponent β because the obvious wavy slip manner of dislocations is conducive to strain homogenization, which is more important for increasing the fatigue life. Therefore, this study gives a comprehensive evaluation and revelation on the effects of aging state on the LCF properties of 2024 alloy.