Reduction effect of final-pass heavy reduction rolling on the texture development, tensile property and stretch formability of ZWK100 alloy plates. (1st June 2022)

• Record Type: Journal Article
• Authors: Shi, B.Q.; Zhao, L.Y.; Shang, X.L.; Nie, B.H.; Chen, D.C.; Li, C.Q.; Cheng, Y.Q.
• Is Part Of: Journal of materials science & technology. Volume 111(2022)
• Page Start: 211
• Page End: 223
• Publication Date: 2022-06-01
• Subjects: Magnesium alloys -- Texture -- Plane anisotropy -- Stretch formability -- Rolled sheets; Metals -- Periodicals; Materials science -- Periodicals; Materials science; Metals; Periodicals; 620.1105
• DOI: 10.1016/j.jmst.2021.09.042
• Languages: English
• ISSNs: 1005-0302

Abstract

Highlights: ZWK100 alloy sheets with initial casting structures was fabricated by final-pass heavy reduction rolling (FHRR) up to 70% single reduction after single-pass rough rolling, and subsequent annealing causes a symmetrical 'oblique-line split' texture instead of the traditional 'TD split' texture. The high rollability for 70% reduction was ascribed to the significant activity of the prismatic 〈 a〉 slip facilitated by the off-basal textures formed after rough rolling The 'oblique-line split' texture was correlated with the preferred growth of grains with [ 1 ¯ 2 1 ¯ 1 ] - [ 1 ¯ 2 1 ¯ 2 ] //RD during annealing. The FHRR-annealed ZWK100 sheets reveal quasi-planar isotropy in mechanical properties ( Δr 2 ∼0.1), large uniform-elongation of ∼35% and excellent stretch formability of 8.1. Abstract: Obviously planar anisotropy due to 'TD 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 low-reduction 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 °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 ∼10 μm and symmetrical 'oblique-line split' texture in (0001) pole figures, with basal poles tilting by about 50° 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 ∼50% and ultra-low planar anisotropy Δ r 2 of ∼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 ¯ 1 ] - [ 12 1 ¯ 2 ] //RD, which was suggested to relate to the high mobility of some special boundaries such as 40°-45° [ 10 1 ¯ 0 ] (∑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 'TD split' orthotropic texture as a counterpoint.