Investigation On Welding Process And Microstructure Of Al-Cu Dissimilar Metal Plate Joint Performed By Magnetic Pulse Welding

In recent years,the miniaturization,light weight,and cost-effectiveness of electric power devices have become a clear trend in the electric power industry.On the premise of guaranteeing the use performance,it is an effective way light weight and reduce the cost by replacing the all-copper components with aluminum and copper composite components.However,the fusion welding process for connecting aluminum and copper is difficult and the quality of the joints is not good.The magnetic pulse welding(MPW)is a solid phase welding technology based on the principles of electromagnetic molding.The base metal does not melt during the welding process,which greatly restricts the production of metal compounds.Therefore,the magnetic pulse welding technology has broad prospects in the welding of dissimilar metals with different physical properties.In this paper,the test material is 1060 aluminum and T2 copper.The welding process and joint morphology of aluminum and copper plate magnetic pulse welding are systematically studied by the method of combination of experiments and finite element simulation.The magnetic pulse welding test was carried out with 1060 Aluminum plate and T2 copper plate as the parent material.The effect of discharge voltage,welding gap and lap welding process parameters on the quality and morphology of the joint was studied by the tensile test,peeling test and weld seam width measurement.The results showed that the optimal gap interval existed in the magnetic pulse welding of the plate;The width of the weld joint and the joint strength were enhanced with the increase of the discharge voltage;When the distance between the aluminum plate and the coil was more than 3mm,the weld was changed from the original flat oval weld joint to the single joint.The morphology of the Al-Cu interface was observed by optical microscope.It was found that the initial morphology of the interface was flat,and the shape of the waveform became obvious with the collision point moving toward both sides.Through SEM to observe the interface and EDS to determine the composition,we found that the diffusion behavior of the element in Al-Cu interface was gradually changed from the diffusion of copper into the aluminum plate to the diffusion of aluminum into the copper plate.At the same time,the line scan results showed that no intermetallic compounds were generated at the detected interface locations.The software Ansoft Maxwell was used to simulate the three-dimensional electromagnetic field in the welding process.The electromagnetic field produced by the coil in the discharge process and the distribution of the electromagnetic force in the aluminum plate were analyzed and studied.Based on the ANSYS finite element analysis software,a two-dimensional model was established,and the loose-coupling method was used to simulate the magnetic pulse welding process of aluminum-copper plate.The simulation results showed that during the magnetic pulse welding process,the induced current direction of the aluminum plate at the coil's center beam position was always opposite to the discharge current in the coil's center beam position.The electromagnetic force received by the aluminum plate mainly concentrated on the position of the coil center beam,and the electromagnetic force reaches the maximum value at the 1/4 cycle of the discharge current.At the same time,the influence of discharge voltage,welding gap,overlap position and coil shape on the electromagnetic force and the collision speed in the process of magnetic pulse welding were analyzed.It provided reference for the selection of welding process parameters and coil design.