The Fracture Behavior of 7085-T74 Al Alloy Ultra-Thick Plate During High Cycle Fatigue

摘要

As a new generation of Al-Zn-Mg-Cu alloy, 7085 Al alloy was first evaluated by high-cycle fatigue (HCF) tests. In the present work, HCF behaviors and the notch sensitivity of a 220-mm-thick 7085-T74 Al alloy ultra-thick plate were investigated. The fracture characteristics of the alloy were investigated, and the crack initiation mode of the alloy was proposed in the present study. The results show that the notch-sensitive coefficient is 0.367, which indicates that the 7085 Al alloy displays a sensitive notch effect. The fatigue crack initiation sites of 7085-T7452 Al alloy ultra-thick plate mainly occurred at the locations of coarse Fe-rich particles on the specimen surface. In addition, compared with smooth specimens, the notched specimens are prone to generating fatigue cracks and usually show more than one crack initiation site.