Forgeability and Flow Stress of Mg-Zn-Y Alloys with Long Period Stacking Ordered Structure at Elevated Temperatures

Abstract

To develop a forging process for high strength Mg-Zn-Y alloys with a long period stacking ordered (LPSO) structure, the forgeability and flow stress of Mg₉₇Zn₁Y₂ (at%) alloys were investigated with the upsettability test at an initial strain rate of 0.55 s⁻¹. As-cast and extruded Mg₉₇Zn₁Y₂ alloys can be successfully forged without fracture up to 0.5 and 1.0 respectively of average equivalent strain at a forging temperature of 773 K. To remove the influence of the temperature change during upsetting from the experimentally obtained flow stress curve, the isothermal flow stress curve was estimated by combining experimental results with finite element analysis. Furthermore, the mechanical properties of the forged Mg-Zn-Y alloys were measured, and the influence of microstructure on the forging properties was discussed.