Abstract
Magnesium alloy is the lightest metal in practical material, and it has excellent specific strength, machinability, recyclability, and vibration absorption. In particular, extrusion material has been applied to the structures in terms of high-strength material can be obtained. In this study, fatigue tests were carried out in laboratory air using an extruded Mg alloy AZ61 to study the distribution of fatigue lives under the different stress ratios. During the fatigue process of the extruded Mg alloy, cracks were initiated from the inclusions existing on the specimen surface. The extreme-value distribution of the defect sizes was investigated experimentally in detail. The crack propagation behavior was analyzed using a modified linear elastic fracture mechanics parameter, M. The relation crack propagation rate vs. M parameter was found to be useful in predicting fatigue lives at different R ratios. Good agreement between the estimated and the experimental results at each stress ratio was obtained.
