During the resistance spot welding of aluminium plates using copper electrodes, the electrode wear is very much higher than in the case of spot welds on steel plates. The diffusion-induced formation of alloys takes place between the copper and the aluminium and there are adhesions of the copper electrodes. If aluminium-copper phases are left behind on the surface of the plate, this results in a constant loss of weight of the electrodes. The influence of the interface contact resistance, of the workpiece surface, of the electrode material, of the electrode geometry and of the contact area on the wear is investigated in this paper. For clarification of the metallurgical processes between the aluminium plate and the copper electrode, diffusion experiments - in order to determine the pickup processes - and energy-dispersive analyses of the alloy layers were carried out.
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