In-situ investigation on the microstructure evolution and plasticity of two magnesium alloys during three-point bending

Three-point bending represents important straining in metal forming, and is an ideal loading condition for in-situ investigation of complex microstructure evolution and plasticity of magnesium alloys. Two extruded alloys with different initial texture, AZ31 (Mg 3%Al-0.5%Zn-1) and AM30 (Mg-3%Al-0.3%Mn), were studied in three-point bending with in-situ electron backscatter diffraction (EBSD) observations, to reveal the role of strain gradient and deformation compatibility in the plasticity of magnesium alloys. The results indicate that strain gradients in macro-scale from tension to compression can lead to a graded microstructure and texture evolution in the samples during bending. At the intergranular and intragranular levels, the volume fraction of twins was influenced by the slip-induced twinning behavior and strain compatibility among the surrounding grains except for Schmid factor relating to grain orientation. Slip-induced twinning behavior and its surrounding effects on the twinning volume fraction is much more profound in materials with weak textures. The AM30 alloy with a weaker texture shows better deformation compatibility (and, thus, formability) during three-point bending compared to AZ31 alloy with a stronger texture in this study. (C) 2015 Elsevier Ltd. All rights reserved.