The structure profile of magnesium alloy tube is difficult to control for complex microstructural evolution under the asymmetric loading of tension and compression induced during tube bending. This study investigates the electro-assisted bending of extruded AZ61 (Mg-6Al-1Zn) magnesium alloy tubes, with particular focus on the influence of pulsed current on microstructure evolution and plastic deformation mechanisms under varying degrees of deformation. The results indicate that pulsed current increases the fraction of {1012} tensile twins and effectively regulates twin nucleation positions along the tangential cross-sections on both sides of the bending head. The initially disordered twin distribution is transformed into a more ordered arrangement, thereby enhancing radial microstructural uniformity during bending. The thermal and electromagnetic energy generated by the current promotes the alignment or polarization of twins and dislocations along specific directions. This phenomenon suggests that pulsed current can improve the formability of magnesium alloy tubes through distinctive microstructural modifications. These findings offer valuable insights into microstructure control and bending ability enhancement of magnesium alloy tube.

Featured initial microstructures of Mg-11Gd-4Y-2Zn-0.5Zr alloy (wt%) were obtained by adjusting temperatures of solid solution and cooling methods, including island intergranular 18R and 14H LPSO phases with low-density stacking faults, differentially spaced lamellar intragranular 14H-LPSO phases, and network intergranular 18R-LPSO phases with high-density intragranular stacking faults. Effects of these featured LPSO phases and stacking faults on dynamic recrystallization (DRX) behavior were investigated via hot compression. Promoted DRX behavior via particle stimulated nucleation (PSN) is introduced by coexisting intergranular island 18R and 14H LPSO phases and intragranular wide spacing lamellar 14H-LPSO phases, contributing the highest DRX fraction of 42.6%. Conversely, it is found that DRX behavior with network intergranular 18R-LPSO phases and dense intragranular stacking fault is considerably inhibited with the lowest fraction of 22.8%. That is, the restricted DRX due to dislocations pinning by stacking faults overwhelms the enhanced DRX behavior via PSN of island intergranular 18R and 14H LPSO phases. Specially, compared with dense intragranular lamellar 14H-LPSO phases, high-density stacking faults exert a larger inhibition effect on DRX behavior.