Twinning activation and dynamic recrystallization behavior of AZ61 tubes in electro-assisted bending

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.