Quantitative study on the tension-compression yield asymmetry of a Mg-3Al-1Zn alloy with bimodal texture components

Abstract

This study demonstrates the yield asymmetry in Mg-3Al-1Zn alloy containing both ND- texture (c-axis // ND (Normal direction)) and TD-texture (c-axis // TD (Transverse direction)) in a quantitative view. The results showed that the yield asymmetry is strongly dependent on the distribution of bimodal texture components, on the basis of the successful establishment of the quantified relationship between pre-deformation parameters and texture components distribution. It's meaningful for providing key reference to texture design. Mechanical behavior of bimodal textured Mg alloy under tension and compression was tested. CYS/TYS (compressive yield stress / tensile yield stress) equal to 1 is obtained, implying that the yield asymmetry is eliminated when two textures distribute at specific fractions. The corresponding mechanism for the texture-dependence of tension-compression yield asymmetry is revealed by the analysis of slip/twinning activities and a compound use of the activation stress difference of slip/twinning (ΔStress) and geometrical compatibility factor (m′) between neighboring grains. Balanced activity of {101¯2} twinning and a quite similar boundary obstacle effect against slip/twinning transfer under tension and compression accounts for such good symmetry performance.