Local twinning behavior of ZK61m magnesium alloy sheet under multiaxial stress during drawing-pressing with Erichsen test machine

Abstract

In order to find a more effective method to preset twins and to explore the microstructure and twin evolution of magnesium alloy sheet under multi-axial stress state deformation, drawing-pressing deformation with Erichsen test machine is used as a sheet processing method to process ZK61m magnesium alloy sheet in this experiment. During repeated drawing-pressing deformation, the central area of the plate was subjected to annular tensile and compressive stress. In the process of deformation under unidirectional force, the slip direction of some grains is in hard orientation and it is difficult for the slip to operate, while the annular tensile and compressive stress state will provide the grains with multidirectional slipping options. Electron back-scattered diffraction (EBSD) technique was used to analyze the microstructure of magnesium alloy plates with different drawing-pressing times and different positions from local deformation center to edge. In this study, the complex circumferential force environment will weaken the anisotropy of deformation structure during repeated drawing-pressing, and the effect of prefabricated twins is more obvious. Based on the modified generalized Schmid factor (GSF) analysis, it is easier to show a variety of twin variation behaviors within a grain during Erichsen deformation. After the plate is deformed by Erichsen processing, the mechanical properties of magnesium alloy sheet have also been effectively improved.