Deformation mechanisms in pure Mg single crystal under erichsen test: Experimental observations and crystal plasticity predictions

Abstract

In the present study, the deformation mechanisms in a pure Mg single crystal deformed under the Erichsen test were investigated. The specimens were deformed for different punch strokes under a given crystallographic orientation relationship with respect to the punch direction at room temperature (RT). The electron backscattered diffraction (EBSD) technique was used for the microstructural study of the deformed specimens. The analysis showed that thin twin bands (TBs), consisting of several twin variants, were heterogeneously generated throughout the specimens. In particular, the specimen with the highest Erichsen Index (IE) value of 6.8 mm showed the most significant twinning activity throughout the thickness. The high stretch formability in the given crystallographic orientation is achieved due to the significant tensile twinning activity, which generates a favorable crystal orientation for the activation of basal slip under subsequent deformation. Furthermore, the crystal plasticity finite element method (CPFEM) was used to elucidate the heterogeneity observed during the experimental analysis by studying the strain component generated, the relative activity of different deformation modes, and the accumulated volume fraction of different twinning variants.