Experimental Investigation On Electrohydraulic Forming Of 5052 Aluminum Alloy Tube

Electrohydraulic forming(EHF) is a typical high energy rate process which has the advantage of efficient production, high formability, good surface quality and sound production environment, etc. Under the shock loading applied evenly on the surface of workpieces, plastic deformation at a higher strain rate occurs, leading to a significant improvement in formability. In this paper, experiments on electrohydraulic forming of 5052 aluminum alloy tubes were carried out under different discharge parameters, and effects of the process parameters on the forming quality were analyzed; “two-step” electrohydraulic forming process was proposed to improve the fitting ability of tube on die. Uniformity in the thickness and plastic deformation behaviors were investigated via comparison between electrohydraulic forming and electromagnetic forming.The transient discharge currents were measured by the flexible current probe.By comparing the forming results and the current waveforms under different discharge parameters, it was concluded that the shock wave intensity in the liquid is not necessarily determined by the peak current; total loop inductance and total resistance decreases and the current oscillation frequency increases while the wire diameter increases; the current frequency decreases during the current rapid decay process. These results could be attributed to the increasing loop inductance induced by the plasma after metal wire gasification.The electrohydraulic forming experiments at different discharge parameters were carried out and the fitting ability under different discharge parameters was studied. The results show that there is an optimal diameter of the wire while giving the discharge voltage. Moreover, the optimum wire diameter increases as the discharge voltage increases, both of which were positively correlated.Two-step electrohydraulic forming process was used to form aluminum alloy tubes, the fillet filling effects of single and two-step electrohydraulic forming were investigated. Compared to a single discharge liquid forming, the two-step method improves the tube shaping and shows a better result of forming process with the complete filling in the die corner zone.It can be concluded that the electrohydraulic forming eliminates the springback effectively, produces a uniform thickness and performs a better deformation in comparison to electromagnetic forming. The circumferential tensile properties of pipes formed by electrohydraulic forming were superior to those formed by the electromagnetic forming under the same deformation. Compared withelectromagnetic forming, electrohydraulic forming remarkably improves the energy efficiency.