Effect of electro-pulse annealing on formability and microstructural evolution of AZ31B magnesium alloy wires during cold drawing

The electro-pulse annealing (EPA) was applied in this work as an effective replacement for the conventional heat treatment (CHT) for intermediate softening, and the influence of cold drawing and annealing conditions on the microstructural evolution and mechanical properties of AZ31B magnesium alloy wires was systematically examined. It is established that EPA promotes the dislocation motion, accelerates the rapid recrystallization, and improves the mechanical performance within 1 min. After EPA, the elongation increases from 4 % to 28 %, the maximum basal texture intensity decreases from 8.26 to 5.58, and the Schmid factor for basal slip increases from 0.15 to 0.21, indicating effective texture modification. In contrast, CHT at the same temperature and time produces little change in microstructure or properties. Only when CHT is conducted at 250℃ for 10 min does the annealed AZ31B wire show microstructure and mechanical properties comparable to those of EPA-treated samples, which confirms the key role of the athermal effects of EPA in improving microstructures and performances. Overall, EPA provides a rapid, efficient, and practical route for intermediate annealing, based on which 1.00 mm AZ31B wires with both high strength and ductility are successfully fabricated.