Promoting Dynamic Recrystallization of Al-Zn-Mg-Cu Alloy via Electroshock Treatment

Abstract

The application of high-strength Al-Zn-Mg-Cu alloy is seriously limited because of its poor formability. A novel electroshock treatment (EST) technique with low frequency combined with tensile deformation was proposed to address the issues of low plasticity and poor formability of Al-Zn-Mg-Cu alloy, which could revolutionize conventional plastic forming methods and realize near-room temperature forming of complex components. Al-Zn-Mg-Cu alloy was examined in this work to figure out how EST affects the tensile characteristics and dynamic recrystallization of the alloy during tensile deformation. The findings demonstrate that when electroshock with a current density of 30 A/mm² and a period of 5 s, the elongation of the alloy increased by 21.74%, and the fraction of dynamic recrystallization increased by 77.56% compared to the sample without EST at a temperature far below the recrystallization temperature. The electron back scatter diffraction (ESBD) results show that after appropriate EST, the average grain size decreased from 40 μm to 30 μm, the distribution of grain was more uniform, and the sample’s grain boundary angle generally increased, which is more attractive to facilitate the nucleation and growth of dynamic recrystallization. Additionally, transmission electron microscopy (TEM) results indicate that electroshock energy motivated the migration of dislocations from the grain interior to near the grain boundaries, improving the ability of Al-Zn-Mg-Cu alloy to dynamically recrystallize at near ambient temperature and enhancing elongation.