Double-pass process was newly performed to a friction stir welded (FSWed) A3003 aluminum alloy /SUS304 stainless steel dissimilar lap joint in order to improve the asymmetry of the FSWed joint. A sound symmetrical joint was produced by running the tool again at the bead which ˆrstly produced by FSW. Tensile strength of specimens was improved by leaving the tool distance from 2 mm to 5 mm where both edges of the stirred zone were advancing side (AS-AS joint). Micro-tensile test revealed that most of the stirred zone in the AS-AS joint with the tool distance of 5 mm fractured at A3003 base metal.

The needs of aluminum joints have grown in recent years. However, as aluminum forms strong oxide layers on the surface in an atmosphere, joining of these materials is di‹cult. This is where we conceived of a new inatmosphere solid phase bonding method which uses high-frequency induction heating and ultrasonic vibration. The effects of ultrasonic vibration and bonding conditions on this new bonding method were investigated. As the results, we were able to confirm the effcacy of ultrasonic waves on bonding. The bonding mechanism of new bonding method was also clear.