Abstract:Butt joining of Al-Cu bilayer sheet produced by cold roll bonding was studied through friction stir welding (FSW). A defect free joint was obtained. Flow patterns and mixing of two layers during FSW were investigated. Microstructural investigations and hardness profile measurements were carried out. It is shown that material flow in stir zone leads to the formation of banding structure in Cu layer at advancing side. Traces of Al particles along with Al-Cu intermetallic compounds exist in the fined grain region of this banding structure which leads to higher hardness values.

Key words: bilayer sheet; Al-Cu sheet; friction stir welding; microstructure