The effects of laser peening on high-cycle fatigue in 7085-T7651 aluminum alloy

This study reports on the high-cycle fatigue performance of 7085-T7651 aluminum treated with combinations of laser peening and anodization. Stress-life fatigue data were generated in a high humidity environment using smooth (Kt = 1) specimens tested at a stress ratio R = 0.1 and a range of maximum stress. Tests were performed in the as-machined (untreated), anodized, laser peened, and laser peened then anodized conditions. The results show that laser-peened specimens exhibited significantly improved fatigue performance, with non-anodized specimens having a factor of 5–14 improvement in fatigue life (depending on stress level) and anodized specimens having a factor of 8–9 improvement in fatigue life. Without laser peening, anodized specimens had reduced fatigue life at all stress levels. With laser peening, anodized and non-anodized specimens had similar lives at high stress (life < 105 cycles) but anodized specimens had shorter lives at low stress. In addition to the fatigue results, surface quality and fatigue initiation locations were evaluated and compared between the specimen conditions.