Strain Heterogeneity Structures in Wrought Magnesium AZ31 Under Reversed Loading

Abstract

Localized strain accommodation, a concern for any structural material with regard to formability and failure, is a particularly prominent issue for Magnesium alloys that possess the unipolar twinning mechanisms and the large differentials between activity ease of slip mechanisms. In this study, for both rolling and extrusion textures of a Magnesium AZ31 alloy, strain heterogeneity levels are characterized by in situ scanning microscopic image correlation. With a nominal 10 μm subset size and spanning over 10⁵ grains, grain-scale strain mapping is conducted over a [−2, 2]% reversed loading cycle. The rolled sample exhibits much sharper patterns that transcend to upper length scales with collaborative activity. The nature of these patterns change depending on the load sense as operational twin mechanisms switch. The extruded sample exhibits the more typical several-grain-long strain localization patterns that follow the grain boundaries. For each case, strain quantification of the localization structures are provided via histograms.