Structure-Property Evaluation of Fatigue Damage in a Magnesium AM30 Alloy

The fatigue properties of an AM30 magnesium alloy extruded into a crash rail-shaped component were evaluated experimentally and numerically. Fully-reversed, strain control fatigue tests were conducted on specimens extracted from regions having varying grain size and texture. Using scanning electron microscopy, the fracture surfaces of each failed specimen were analyzed in order to establish the relationship between microstructure and fatigue behavior. Texture and grain size were identified through EBSD analysis. Parallels between microstructural features such as particle size, grain size, Taylor factor, and the number of cycles to failure were determined. The numerical analyses concerned simulation of the fatigue life to failure using a microstructure-based multistage fatigue model originally developed for cast aluminum alloys and later adapted for magnesium.