Fatigue behavior and life prediction of cast magnesium alloys

Fatigue behavior of magnesium castings has been investigated with NZK (Mg-Nd-Zn-Zr) alloys and other magnesium alloys including AZ91D, GW103, and AM-SC. Multi-scale fatigue (MSF) life models have been adapted to estimate fatigue lives of the magnesium castings studied. Results indicate that fatigue failure of magnesium alloys with few casting defects is dominated by crack initiation first within a grain close to the free surface and then propagation in trans-granular mode through either twin grain boundaries in the T4 heat treatment condition or from persistent slip bands in the T6/T7-treated condition. The fatigue life of cast magnesium alloys can be well predicted using multi-scale fatigue (MSF) models together with characteristic microstructure constituent - grain sizes.