Hot deformation analysis and microstructure evolution of Al–Mg–Mn-Sc-Zr alloy by isothermal compression

Abstract

In this work, a new type of Al–Mg–Mn-Sc-Zr alloy was compressed under different temperatures (300 °C–450 °C) and different strain rates (0.0001 S-1 to 10 S−1). The hyperbolic sinusoidal Arrhenius flow stress constitutive equation and the constitutive equation of flow stress related with Z parameter have been calculated. In addition, the processing maps based on dynamic material model (DMM) at different strains have been established. The results show that deformation behavior and microstructure evolution of the alloy are significantly affected by deformation temperature and strain rate. The flow stress decreases with the increase of the temperature or the decrease of strain rate. Meanwhile, increasing the temperature or decreasing the strain rate, the average grain boundary (GB) angle and the high angle grain boundary (HAGB) fraction will rise and it is beneficial for dynamic recrystallization (DRX) or dynamic recovery (DRV). The dislocation density of the 1 S−1- 300 °C, 0.0001 S-1- 300 °C, 1 S−1- 450 °C and 0.0001 S-1- 450 °C samples are 1.19 × 1014/m2, 5.97 × 1013/m2, 6.52 × 1013/m2 and 2.03 × 1013/m2 respectively. Moreover, under very low strain rate, some grains would combine together and the morphology of the Al3(Sc, Zr) particles would change. In the 0.0001 S-1- 450 °C sample, some particles have lost the coherency. This is due to the co-effect of the high temperature and the very low strain rate.