The Effect of Pulse Electric Current on the Mechanical Properties and Fracture Behaviors of Aluminum Alloy AA5754

Abstract

The influences of pulse electric currents at energy density levels of 0.105 J/mm3 and 0.150 J/mm3 on AA5754's flow stress and elongation are investigated. Different combinations of current density and pulse duration are carried out for each energy density. The nonJoule heating effects in electrically assisted forming (EAF) are revealed since the temperatures generated by the electric currents of the same energy density are identical. It is observed that a pulse current helps reduce AA5754's flow stress and increase its elongation. At the same level of energy density, as the current density increases, the instant drop of stress increases as well as the elongation, although the maximum flow stress remains almost unchanged. A theoretical model is proposed that can predict the stress drop during electrically assisted forming. The fracture surfaces of AA5754 subject to pulse currents are observed and analyzed. The dimples of fracture continue to decrease until they completely disappear as the density of pulse current increases. The suppression of voids nucleation and growth by a pulse current leads to the increase of total elongation.