The Effect of Oxide Film on the Strength of an Ultrasonically Welded Joint, and Welding Process

Study on the Ultrasonic Welding of Dissimilar Metals (2nd report)

Abstract

In this study, the effect of oxide film on the strength of the dissimilar-metal joint performed with ultrasonic welding process was investigated. Furthermore, we examined the fracturing behavior of the thick oxide film, which was anodized on the aluminum surface, during ultrasonic welding between aluminum and copper or SUS304, and presumed the joining process. The obtained results are as follows.
In the joining of aluminum-copper, the strength of the joint decreases with increasing in thickness of the oxide film on the copper surface. However, the increase in the thickness of the oxide film on the aluminum surface has no effect on the strength of the joints of aluminum-copper or aluminum-SUS304.
At the welding interface of aluminum-copper, the aluminum oxide film is partially broken and the welded area is gradually increased as welding time increases. In the case of aluminum-SUS304, the aluminum oxide film is broken over the whole area of the interface at the initial stage of welding, and the welded area and the joint strength increase abruptly.