Characterization of hot deformation behavior of extruded ZK60 magnesium alloy using 3D processing maps

Abstract

The hot deformation behavior of extruded ZK60 magnesium alloy was investigated by compression tests in the temperature range of 250–400°C and strain rate range of 0.001–1s−1. In order to describe the flow characteristics, a constitutive equation was developed and the deformation activation energy was estimated to be 126.31kJ/mol. The three-dimensional (3D) processing maps were established on the basis of experimental data as a function of temperature, strain rate and strain. According to the 3D processing maps, it can be found that the strain has a significant influence on the efficiency of power dissipation and the regions of flow instability. From the 3D power dissipation map, one domain of dynamic recrystallization (DRX) and the other domain of superplasticity were identified and the flow instability regions were distinguished from the 3D instability map. By means of user subroutines, the 3D processing maps were integrated into the commercial finite element (FE) software MSC.Marc and the distributions of the flow instability region during processing can be predicted. In addition, the processing maps of extruded ZK60 alloy have been compared with those of as-cast alloy, which demonstrates that the hot extrusion process improves the workability of the alloy.