Influence of thermal deformation on deformation behavior of high-temperature flow of Al-Sc-Zr alloy for automobiles and establishment of constitutive equations

A one-way thermal compression experiment of Al-0.2Sc-0.04Zr aluminum alloy on the Gleeble -3000D thermal simulator was conducted to study the thermal deformation behavior under the strain rate of 0.001~5 s^-1 and a thermal deformation teperature of 440~600 ℃. The results show that the degree of dynamic recrystallization increases with increasing deformation temperature or decreasing strain rate. Meanwhile, for deformation at lower temperatures (T≤520 ℃), the main softening mechanism is dynamic recovery, and for deformation at higher temperatures (T>520 ℃), the softening mechanism changed to a dynamic recrystallization softening mechanism, obtaining a relatively complete dynamic recrystallization structure. Deformed at high temperatures (T≥600 ℃), the grains grow significantly. By analyzing the stress index and the deformation activation energy, the stress index (n) increases with increasing deformation temperature. The deformation activation energy (Q) increases with increasing deformation temperature and strain rate within the range of experimental temperatures. The peak stress of the Al-0.2Sc-0.04Zr alloy was analyzed by the hyperbolic-sine Arrhenius constitutive equation, and the average absolute relative error (AARE) between the predicted value and measured value of the alloy is only 7.428% as well as the correlation coefficient (R) 0.9708.