Abstract
The effect of aging treatment on fatigue behaviour in extruded Mg alloys AZ61 and AZ80 was investigated. Rotating bending fatigue tests were performed using as-received and aged specimens. Iin both materials, Mg_<17>Al_<12> precipitated near grain boundaries by aging treatment. Although aging treatment could improve static strengths, it was detrimental to the fatigue limits in both materials. Fatigue cracks initiated at the boundaries between Mg_<17>Al_<12> and the matrix, resulting in lower crack initiation resistance and fatigue limits. The detrimental effect of aging treatment on fatigue limit was more pronounced in AZ80 whose Al content was higher than AZ61.
