Fatigue properties of the hot extruded magnesium alloy AZ31

The fatigue properties of differently extruded magnesium alloy AZ31 and hence different microstructures were investigated during total strain and stress-controlled fatigue tests with different applied strain and stress amplitudes, respectively. Extruded magnesium profiles exhibit a significant asymmetry in the quasi-static mechanical properties under tension and compression, due to the low activation energy for the { 1   0   1 ¯   2 } 〈 1   0   1 ¯   1 〉 extension twinning. The asymmetry of the tension–compression yield strength leads to a sigmoidal shape of the hysteresis loops under cyclic loading conditions which is reduced if the tension–compression asymmetry is reduced. Moreover the evolution of stress and strain amplitudes, the plastic strain amplitudes and the mean stress and strain were analyzed. The Manson–Coffin and the Basquin approaches were used to describe the lifetime of the differently extruded products.