LAUSR

Strain-controlled fatigue characteristics of peak-aged and over-aged Mg96.47Nd2.9Zn0.21 magnesium alloys containing 0.42Zr, including stress response, strain resistance, hysteresis loops, strain–life and corresponding low-cycle fatigue life prediction model, were studied. In the peak-aged state (T61: 540 °C × 8 h + 200 °C × 14 h), the alloy shows higher cyclic stress response, but lower ductility than the alloy in the over-aged state (T62: 540 °C × 8 h + 200 °C × 400 h). The yield strength and ultimate tensile strength of the alloy under T61- and T62-treated conditions are close. Compared with T61-treated alloy, the steady stress amplitude occurred in T62-treated alloy is due to higher ductility and more homogenous deformation. In T61 state, the fatigue cracks in the alloy first initiate along the cracked persistent slip bands and then propagate in the trans-granular mode, while in the T62 state, the fatigue cracks initiate along grain boundaries and then propagate in the inter-granular mode.