Abstract
In order to investigate fatigue properties of extruded magnesium alloys in very high cycle regime, rotary bending fatigue test was performed in ambient atmosphere at room temperature using the hourglass shaped specimens of AZ31 and AZ61 alloys. From the experimental results, S-N curves of both specimens exhibited a smooth and continuous transition from the low to high cycle fatigue regime and did not appear the fatigue limit. Fatigue strength at 109 cycles of AZ31 and AZ61 alloys was 100MPa and 130MPa, respectively. The ratio of fatigue strength at 109 cycles to tensile strength was 0.43. It was observed on the fracture surface by SEM to be a facet-like smooth area at crack initiation site and an uneven-stripe pattern in crack growth region, which could be formed by twin deformation during fatigue process.
