Hot deformation behavior and microstructural evolution of an Al-Mg-Si-Cu-Mn-Fe alloy: constitutive modeling, processing map, and softening mechanisms
摘要
In this study, we investigated the hot deformation behavior of an Al-1.2 Mg-0.8Si-2.0Cu-0.5Mn-0.1Fe alloy through hot compression tests conducted on a Gleeble-3500 thermal simulation machine. The experiments were conducted at deformation temperatures of 410–500 °C and strain rates of 0.01–5 s−1. A constitutive model was derived based on the Arrhenius equation. The experimental results are in good agreement with the predictions of both the developed constitutive equation and the Avrami-type dynamic recrystallization (DRX) model, indicating that both models offer high predictive accuracy. A hot processing map at a strain of 0.8 was constructed using the dynamic material model (DMM). Stable hot processing conditions for the alloy were predicted to occur within a temperature range of 410–500 °C and a strain rate range of 0.01–0.1 s−1, while the optimal processing conditions are determined to be 440–470 °C and 0.01–0.1 s−1. Analysis combining the flow softening curves and hot processing map reveals that the alloy achieves maximum softening efficacy at a strain rate of 0.1 s−1 across varying deformation temperatures. The post-deformation microstructures were characterized by optical microscopy (OM), scanning electron microscopy (SEM), and electron backscatter diffraction (EBSD) to clarify the microstructural evolution mechanisms. Findings demonstrate that at lower temperatures, the dynamic softening mechanisms predominantly involve dynamic recovery (DRV) and continuous dynamic recrystallization (CDRX). As the deformation temperature rises, a combination of DRV, CDRX, and discontinuous dynamic recrystallization (DDRX) becomes prominent.