A Study Of Dissimilar Alloy Materials’ Ultrasonic Welding Process And Its Mechanism

The working principle of ultrasonic metal welding(UMW) use pressure and high frequency shearing motion to achieve solid connection between materials; it is one of high efficiency and convenient welding processing technologies. Though UMW is widely used in the industry, however, now there still have defects on bonding mechanism of welded joint. In order to use this technology better, This paper has conducted a profound research on the bonding strength and mechanism of dissimilar alloy metals(0.1mm of aluminum plate and nickel plated steel of lithium battery electrode tab)by ultrasonic welding.Primary, in the experiment, the peel strength of welded joint is measured by CETR sample test system and the influence research of different welding parameters on bonding strength is analyzed by single factor and orthogonal analysis method in this paper. Subsequently, the hardness of welded joint is measured by digital micro hardness tester, in order to obtain the change rule of different welding parameters on refinement degree of welding seam; and the weldment is welded by using stepping amplitude and constant amplitude, to analyze the influence action of different welding model on bonding strength and surface morphology of welded joint. Finally, the welded microstructure is observed by 3D laser scanning microscope methods, in order to analyze and summarize bonding mechanism of welded joint of ultrasonic metal welding.The results showed that there are three kinds of welding parameters(welding time, welding amplitude and welding pressure)have a certain influence for joint’s strength by single factor analysis method. Moreover, evidences indicated that welding amplitude is the strongest influence factor by orthogonal analysis method. In the hardness measurement, the influence degree of welding amplitude is greater than welding time, so it can show that welding amplitude will improve the refinement degree of metal grains. When adopt the step amplitude in the process of welding, it can not only obtain higher strength of welded joint, but also it will has a stable standard deviation of strength, furthermore adhesion between weldment surface and the tool will be reduced, therefore the weldment surface is smooth before peel test, with the consequence that it may reduce the crack occurs in soft metal. After the observation of microstructure morphology of weld, evidences shows that the metal surface oxidation film can be broken by UMW yet these is not detected any serious melting phenomenon in metal-binding domain, nevertheless the metallic bonding and physical metallurgy plays a key role in the welded joint’s formation, and this is the premise of the solid-state bonding.