The rebound suppression and rapid solid solution of Al–Zn–Mg–Cu alloy under high-density electropulsing

As a high-strength aluminum alloy, Al–Zn–Mg–Cu alloy is widely used in aerospace and aviation applications. Due to the high yield strength and low modulus of elasticity, Al–Zn–Mg–Cu alloy is prone to springback problems during processing, which limits the high-precision forming. Numerous studies have been conducted to eliminate or minimize springback. Recently, pulsed current assisted forming has been reported to mitigate springback. However, the underlying mechanism of the non-thermal effect on springback remains unclear. The mechanism of reducing springback of Al–Zn–Mg–Cu alloy by high-density electropulsing treatment was investigated by experiments, microstructure characterization and theoretical analysis. The results show that springback decreases as discharge voltage increases, and is fully eliminated at 10 kV (with a peak current density of 9210 A/mm2). Comparing the results of isothermal experiments, it is found that the electrothermal effect is not the only reason for the reduction of springback, but the electromagnetic effect of pulse current also plays an important role. Furthermore, electropulsing promotes the dissolution of the secondary phase, resulting in a reduction in strength, which can be recovered by the subsequent artificial aging.