Multiaxial fatigue behavior of low‐temperature closed‐die forged ZK60 extrusion under proportional and non‐proportional loading

Abstract

Uniaxial and multiaxial fatigue characteristics of as-extruded and extrudedthen-forged ZK60 magnesium alloys were examined to understand the influence of low-temperature forging on its deformation mechanics. Upon forging, basal texture weakening and grain refinement occurred in ZK60 extrusion. Based on uniaxial results, forging process led to improvements in quasi-static tensile strength and axial cyclic response in high-cycle fatigue regime, whereas shear responses remained unaffected. Biaxial non-proportional tests demonstrated that changing phase angle shift between axial and torsional waveforms had no effect on cyclic axial response, contrary to the shear response. Lastly, critical-plane and energy-based life prediction models were assessed.