Abstract
Fatigue tests under alternate bending stress in air and argon gas were carried out for the notched sheet specimens of AZ31 magnesium alloy at temperatures from room tcmperature to 150°C. The fatigue strength at 150°C is some three-fifths as much as that at room temperature. This lowering in fatigue strength well corresponds to that in tensile strength. Within the above test temperature, the relation between σ/σB and Nf is described approximately on a same curve. Also, the relation between crack propagation, rate and stress intensity factor in the steady stage of crack propagation is represented nearly by a same line on both logarithmic scales, though it depends somewhat on temperature. The fracture mode is predominantly transgranular cracking but in the early stage of crack propagation intergranular cracks become to appear at 150°C. No clear defference between the results obtained in air and argon gas is observed.
