Characterization and modeling of {101¯2} twin banding in magnesium

We experimentally and numerically examined the localization behavior of {101¯2} extension twins in strongly and weakly textured AZ31 and ZEK100 magnesium alloys as they depart from the surface toward the center of the sheet under the mechanical action of three-point bending. Strain measurement analysis using digital image correlation revealed that twin banding occurs only in the sharply textured AZ31, but with a characteristic spacing between the bands which decreases with the twin height and applied strain. ZEK100 did not exhibit any ordered localization of bands and behaved as a “true” polycrystal. This finding is in agreement with micromechanical calculations by the present authors. We show that full-field plasticity finite element crystal plasticity model was unable to capture many important 2D features of the twin banding. This suggest that twin shear transfer, non-local effects, and the third dimension effects should be included into this model.