Effect of inherent microtexture on strain heterogeneity in rolled magnesium AZ31

Abstract

The level of utilization of magnesium alloys in engineering practice is steadily increasing, mainly due to their high specific strength. Their complex mechanical be havior, however, requires characterization at microstructural length scales to achieve reliable designs. In this study, mesoscale strain fields are investigated in detail on wrought Magnesium AZ31. For this purpose, two dogbone samples cut from orthogo nal faces of a rolled Magnesium AZ31 plate are subjected to uniaxial tension along the rolling direction. In these experiments, using in-situ multiscale digital image correla tion technique (DIC), the deformation heterogeneities in elastic and early plastic regime are investigated. DIC combination maps in terms of strain and rotation that depict the deformation character are produced. Strain heterogeneity patterns are observed as flat bands and non-45◦ bands on the surface normal to transverse direction (TD) of the plate while flat bands and thick horizontal localization structures are noted on the orthogonal normal-direction (ND) surface. Strain localization structures are distinguished by applying data filters. Then, the spatial characteristics of individual localization structures are explained with the content of rotation and Poisson’s ratio. Detailed measurement over two orthogonal faces allows volumetric interpretation of plastic localization structures. Thus, it is understood that the non-45◦ bands observed on TD-normal surface are widespread three dimensional structures which appear al most horizontal on the ND-normal surface. It is shown that these bands play dominant role in material deformation despite their low volume fractions. Their association with heterogeneous microstructure that is inherited from the rolling process is investigated with electron back scattering diffraction.