Strain localization structures in textured magnesium AZ31 under reversed loading via microscopic digital image correlation

Abstract

In favorable crystallographic texture and loading path combinations, Magnesium AZ31 deformation is dominated by twinning. A marked component of the material behavior in this regime is the spatial distribution of the accommodated strain: there is sharp strain localization at every length scale including macroscopic, stemming from an abrupt propagation of twinning events across neighboring grains (e.g., Aydiner and Telemez, Int. J. Plas. 2014(56), p. 203). Strain mapping with digital image correlation (DIC) has been instrumental in bridging length scales and highlighting strain heterogeneity levels in this material. With a multiple-optical-axis DIC apparatus, strain maps are obtained with macroscopic and microscopic resolution for the full field. For the sharp rolling texture, strain heterogeneity patterns can be directly interpreted on the micro-mechanisms of the abundant orientation. These patterns are presented at representative points of the reverse-loading cycle and interpreted with respect to operative twin and slip mechanisms.