Elimination of in-plane mechanical anisotropy and enhancement of strength-ductility of rolled Mg sheets via electric-associated twinning and recrystallization

A novel method referred as electric-associated corrugated wide limit alignment (E-CWLA) was proposed to address the contradiction between strength and plasticity of hot-rolled Mg sheets. The counterpart without electricity was known as CWLA. A huge number of tensile twins (TTs) was induced in CWLAed sample R300, and dynamic recrystallization (DRX) occurs. Strong transverse direction (TD)-titled texture accounts for the huge difference in yielding strength between different loading directions, which are closely related to Schmid factors of prismatic and pyramidal slips, resulting in different ultimate tensile strength (UTS) and ductility of R300 along different directions. E-CWLAed sample E300 presents good in-plane mechanical isotropy with the maximum UTS of 272.1 MPa, yielding strength of 213.6 MPa and elongation of 22.7%, increasing by 32%, 53% and 83% compared with the as-received sheets, respectively. Regardless loading direction, basal and non-basal slips possess similar SFs and greatly facilitates uniform plastic deformation and mechanical isotropy of E300. The special microstructure including lots of fine grains, some large grains and TTs results in a bimodal basal texture with very weak TD-titled component promotes its good deformation compatibility. Electricity contributes little to TTs formation of E300, and its thermal effect promoting dislocation mobility and DRX and the athermal effect increasing DRX nucleation rate are responsible for final grain size distribution.