Microstructural and constitutive relationship in process modeling of hot working: The case of a 60Mg-30Pb-9.2Al-0.8B magnesium alloy

Hot compression tests in the temperature range of 493-653 K and strain rates of 0.01-10.00 s-1 were used to evaluate the hot deformation behavior of 60Mg-30Pb-9.2Al-0.8B alloy. In order to optimize the hot working parameters, the Arrhenius constitutive equation and processing map with strain compensation were established on the dynamic material model (DMM). The results show that the stress-strain curves have three different stages of rising, peaking, and steady state during the hot compression with typical characteristics of work hardening (WH), dynamic recovery (DRV), and dynamic recrystallization (DRX). In addition, the improved Arrhenius strain compensation constitutive model has a higher precision than the traditional constitutive model. By dividing the processing map into three typical regions for analysis, the maximum power efficiency is obtained at ε = 0.4. The optimum hot working parameters are temperature range of 573K∼ 653K, and strain rate range of 0.01 s-1∼0.1 s-1. Instability usually occurs in the region with high strain rate and low temperature, and the main form of instability is cracking.