Improvement in mechanical properties of Al-Zn-Mg alloy by applying electric pulse during hot extrusion

摘要

For the first time, an electric pulse was applied during the hot extrusion of an Al-Zn-Mg alloy. Extrusion experiments were conducted with and without the presence of the electric pulse to compare the effects of the electric pulse on the microstructure and mechanical properties of the extruded alloy. The grain growth behavior was promoted by the thermal effects, and dynamic recrystallization was promoted by the athermal effects. Therefore, the width of the elongated grains slightly increased; further, both the fraction and the grain size of recrystallization also increased. It was observed that the types of textures were not affected; however, the fractions of the textural components changed and their intensity was enhanced. The electric pulse significantly enhanced the elongation of the extruded alloy and slightly decreased its ultimate tensile strength. The elongation of the sample extruded with an 80-V/250-Hz electric pulse was highest, at 11.9%, which was 19% higher than that of the sample that received no electric pulse. Moreover, both the hardness and resistance to intergranular corrosion were enhanced by the electric pulse.