Construction of Dynamic Recrystallization Critical Strain Model, Kinetic Model, and Hot Workability of Mg–8Gd–4Sm–1Zn–0.5Zr Alloy

The dynamic recrystallization (DRX) behavior and hot workability of Mg–8Gd–4Sm–1Zn–0.5Zr alloys are investigated by the Gleeble-1500 test machine. The tests are performed at 350–470 °C with a strain rate of 0.002–1 s⁻¹. The results show that the stress–strain curves exhibit a typical single-peak DRX behavior. The DRX critical strain model of the alloy is constructed according to the inflection characteristics of the work hardening rate curve. The DRX kinetic model is constructed according to Avrami equation. The 3D processing maps are obtained based on the dynamic material model. The mechanisms of instability regions are investigated by combining the processing map and the microstructural evolution, and the most suitable regions for hot working are identified. The critical strain ε_c of the alloy is reduced at higher deformation temperatures or lower strain rates, and the DRX more easily occurs. That is, the material is more suitable for hot working. The optimum domain for hot working of Mg–8Gd–4Sm–1Zn–0.5Zr alloy is the temperature range of 400–470 °C and strain rate range of 0.002–0.05 s⁻¹.