Tailoring microstructure and texture of Mg–3Al–1Zn alloy sheets through curve extrusion process for achieving low planar anisotropy

Abstract

• Symmetric curve extrusion (SCE) and asymmetric curve extrusion (ACE) processes were firstly proposed to fabricate AZ31 Mg alloy sheets. • The SCE and ACE sheets exhibited unique textures which were ascribed to the introduction of additional flow velocity difference along transverse direction during extrusion. • The ACE sheet exhibited the lowest basal pole intensity because of the introduction of extra asymmetric shear deformation during ACE process. Curve extrusion processes, including symmetric curve extrusion (SCE) and asymmetric curve extrusion (ACE) processes, were proposed to fabricate Mg–3Al–1Zn (AZ31) alloy sheets with the aim of improving planar anisotropy. For comparison, traditional extrusion (TE) was conducted on producing AZ31 sheets. The dynamic recrystallization and flow behavior of AZ31 Mg alloy during extrusion were examined and analyzed, and the final microstructures and mechanical properties of AZ31 sheets were investigated. In comparison with the TE sheet, finer grain size, more uniform microstructure and weaker tilted basal texture were achieved in the SCE and ACE sheets. Both the SCE and ACE sheets exhibited unique textures which basal poles tilted to extrusion direction (ED) and new transverse direction (TD)-tilted texture component was developed. The reasons were mainly ascribed to the introduction of additional flow velocity difference along TD during extrusion. Furthermore, the ACE sheet exhibited the lowest basal pole intensity, which was attributed to the introduction of extra asymmetric shear deformation during extrusion process. As a result, the ACE sheet showed the lowest yield strength and r -value, but highest elongation and n -value. Improving the planar anisotropy of AZ31 sheet was achieved by the ACE process.