Fatigue Assessment of Aluminium Alloy

This research presents a detailed evaluation of the fatigue behavior of A7075-T6 aluminium alloy under fully reversed rotating bending stress conditions. Utilizing ASTM E466 standards, a series of fatigue tests were performed on cylindrical specimens at varying stress amplitudes from 300 MPa to 550 MPa. Stress-life (S-N Curve) data were generated and correlated with microstructural characteristics and fractographic features obtained via Scanning Electron Microscopy (SEM) and Optical Microscopy (OM). The results demonstrate a distinct fatigue threshold near 350 MPa and a transition from high-cycle to low-cycle fatigue with increasing stress. Weibull statistical analysis was applied to model the reliability of fatigue life predictions. Fractographic observations revealed surface-initiated crack propagation with dominant striation patterns, while the role of MgZn2 precipitates was found critical in crack nucleation. These findings contribute valuable insights for aerospace and automotive applications where fatigue resistance is paramount.