Experimental investigation into the electropulsing assisted punching process of 2024T4 aluminum alloy sheet

During the punching process of high strength lightweight materials such as 2024T4 aluminum alloy, the severe die wear and edge fracture of the punched part are one of the main concerns of manufacturing industries and the scientific community. Researches have found that the electric current can reduce the metals’ flow stress, improve their ductility, and promote the dislocation annihilation below the annealing temperature. Therefore, the electric current was proposed to help improve the punching process of 2024T4 aluminum alloy sheet in this paper. The experiments of electropulsing assisted punching (EAP) were carried out by applying different values of electric current on the specimens at different punching phases. For convenience to compare the punching results, the punching load, the surface quality of the punched profile and edge strain hardening (ESH) were analyzed under different electropulsing ways. In addition, the uniaxial tensile tests of punched parts were carried out to evaluate the influence of electropulsing on the ultimate tensile load of punched specimen with a hole. The results show that the electropulsing has a significant effect on reducing the punching load and improving the surface quality of the punched profile. Moreover, the anisotropy of material and the ESH of the punched edge, which are characterized by the level or distribution of microhardness, are eliminated partially due to the electropulsing induced annealing effect. The ultimate tensile load has been effectively enhanced by electropulsing, which may stem from the fact that elimination of ESH and the healing and arrest of microcracks and microvoids near punched edge.