Reduction effect of final-pass heavy reduction rolling on the texture development, tensile property and stretch formability of ZWK100 alloy plates

Obviously planar anisotropy due to ID split' orthotropic texture (TD indicates Transverse direction) always exist in the Rare-earth (RE) or Ca containing Mg alloy sheets, which is likely caused by the lowreduction rolling (and annealing) as revealed in our previous research. In this work, the as-cast billets of a ZWK100 alloy were subjected to final-pass heavy reduction rolling (FHRR) at 500 degrees C with different reductions (30%-70%) after rough rolling, aiming to investigate the reduction effect on the microstructure and texture formation. The results show that FHRR with higher reductions above 50% is in favor of shear banding formation but has little effect on the as-deformed texture components, and the excellent formability with single-pass reduction up to 70% is mainly ascribed to the activation of prismatic (a) slip. FHRR with reduction above 50% and annealing can generate uniform grain structures of similar to 10 mu m and symmetrical 'oblique-line split' texture in (0001) pole figures, with basal poles tilting by about 50 degrees from ND (Normal direction) towards some oblique-line of TD and RD (Rolling direction) as well as uniform distribution of counter lines as an annular shape, resulting in excellent elongation to failure of similar to 50% and ultra-low planar anisotropy Delta r(2) of similar to 0.1 and high stretch formability (Erichsen value: 8.1). The formation 'oblique-line split' texture in (0001) pole figures is mainly correlated with the preferred growth tendency of grains with [21 (1) over bar1]-[12 (1) over bar2]//RD, which was suggested to relate to the high mobility of some special boundaries such as 40 degrees-45 degrees[10 (1) over bar0](Sigma 14). The influences of starting textures on the mechanical properties, planar anisotropy and related deformation modes, as well as their correlations with the stretch formability were comparatively investigated with the ID split' orthotropic texture as a counterpoint. (C) 2021 Published by Elsevier Ltd on behalf of Chinese Society for Metals.

Automated summary

By subjecting the as-cast billets of ZWK100 alloy to final-pass heavy reduction rolling (FHRR) at different reduction rates, it was found that reductions above 50% favored shear banding formation and led to uniform grain structures with symmetrical 'oblique-line split' texture, resulting in excellent elongation and formability. The formation of the 'oblique-line split' texture was mainly correlated with the preferred growth tendency of grains with special boundaries, contributing to the high stretch formability of the alloy.