Twinning behavior of a strongly basal textured AZ31 Mg alloy during warm rolling Original Research Article

The twinning behavior of a strongly basal textured magnesium alloy AZ31 plate during warm rolling to a reduction of 9% has been investigated. Analysis of the twin types and twin variants was carried out based on orientation data collected using electron backscatter diffraction. Double twins (corresponding to contraction twinning followed by extension twinning) were the most commonly observed twin type, with more than 70% of the grains examined containing this type of twin. The double twin variant with a 38° misorientation to the original grain orientation was the most frequently observed, with the 30° variant being the next most frequently observed. The twinning variant selection was analyzed using both a modified Schmid factor for rolling and by use of normal strain maps, used to show the compatibility between the normal strains due to twinning and the applied rolling deformation. It was found that the 38° and 30° misorientation double twin variants provide normal strains that are similarly compatible with the applied deformation, with a slight advantage for the 30° variant. Overall, the results show that for rolling deformation external strain accommodation, rather than self-strain accommodation, is the dominant factor in determining the variant types of the double twins formed during warm rolling.