Characterization of flow behavior and microstructural evolution of Al-Zn-Mg-Sc-Zr alloy using processing maps

The flow behavior of Al-Zn-Mg-Sc-Zr alloy and its microstructural evolution during hot compression deformation were studied by thermal simulation tests. The tests were carried out in deformation temperature range from 340 to 500 degrees C and at strain rate range from 0.001 to 10 s(-1). The results show that deformation temperature and strain rate have significant influence on the flow behavior of Al-Zn-Mg-Sc-Zr alloy. The flow stress increased with increasing strain rate, and decreased with increasing deformation temperature. In order to demonstrate the workability of Al-Zn-Mg-Sc-Zr alloy further, the processing maps at strain of 0.3 and 0.5 were established respectively based on dynamic materials model. The dynamic recrystallization of Al-Zn-Mg-Sc-Zr alloy occurred at deformation temperature of 420 degrees C and a strain rate of 0.01 s(-1). At higher deformation temperature or lower strain rate, the grain size as well as the volume fraction of the recrystallized grains increased. At strain of 0.3 and 0.5, the flow instability domain mainly located at higher strain rate ( > 0.4 s(-1)). On the basis of the processing map and microstructural evolution, the optimum processing conditions at a strain of 0.3 are in the strain rate range of around 0.001-0.1 s(-1) and deformation temperature range between 380 and 440 degrees C. (c) 2012 Elsevier B.V. All rights reserved.