Fatigue performance of high-pressure waterjet-peened aluminum alloy

An experimental study of high-pressure waterjet peening on 7075-T6 aluminum alloy was conducted to investigate the effects of waterjet on high -cycle fatigue life and fatigue crack growth. Unnotched hourglass-shaped circular cross section test specimens were fatigue tested in completely reversed rotating bending (R = S-min/S-max = -1) to determine fatigue life behavior (S-N curves). Single-edge-notched flat tensile test specimens were tested in the tension-tension fatigue crack growth tests (R=S-min/S-max=0.1) to determine fatigue crack propagation behavior (da/dN versus DeltaK). Surface characteristics and fracture surfaces were evaluated by scanning electron microscopy (SEM). Results show that waterjet peening can increase high-cycle fatigue life, delay fatigue crack initiation, and decrease the rate of fatigue crack propagation.