Texture optimization on Mg sheets by preparing soft orientations of extension twinning for rolling

Abstract An in-plane precompression and annealing process (PCA) was carried out on a Mg–3Al–1Zn thin sheet to introduce a completely tilted texture. Unlike the conventional c-axis∥normal direction (ND) basal texture which usually hinders the deformation ability of the Mg sheet during secondary forming, such a special texture component could supply soft orientations of extension twinning for subsequent rolling. The results indicated that the new grain orientations induced by extension twinning, which are dependent on consuming the pre-introduced tilted texture during rolling, would lie around the ND. This positioning could offer diverse orientation gradients along different directions. Meanwhile, such randomly distributed orientation gradients could provide relatively random growth directions for the new recrystallized grains during annealing and contribute to weakening of the basal texture, as well as promoting the symmetry of texture distribution (distribution of basal poles show rotational symmetry around the (0002) pole figure center). As expected, the “precompressed + annealed” and subsequently “rolled + annealed” sample showed improved uniaxial tensile properties (including lower yield strength, higher ductility and more symmetrical planar mechanical performance along different directions) and a considerably improved multiaxial stamping property (Erichsen value increased ~120%) compared with that of the as-extruded sheet or the directly rolled and annealed sample. This study confirmed that preparing soft orientations of extension twinning for subsequent rolling (e.g., employing in-plane precompression along with rolling processes) could be a highly efficient way to optimize the texture and mechanical properties of Mg sheets.