Effect of aging treatment on fatigue behaviour in extruded AZ61 and AZ80 magnesium alloys

The effect of aging treatment on fatigue behaviour in extruded Mg alloys AZ61 and AZ80 was studied. Rotary bending fatigue tests were performed using as-received and aged specimens. Two different aging conditions, T6 and T5, were evaluated. Mg17Al12 precipitated near grain boundaries and within grains by aging treatments. In both materials, the T6-treated specimens showed significantly lower fatigue strength than the as-received specimens, which was more remarkable in AZ80, while the T5-treated specimens exhibited slightly higher fatigue strength in AZ80. It was indicated that the effect of aging treatment on fatigue strength was mainly attributed to the change in fatigue crack initiation mechanism.