Microstructure and mechanical properties in dissimilar friction stir welding of aluminium alloys

Friction stir welding is a gateway for joining the two dissimilar lightweight materials, and the implementation is applicable for various industries. In the present work, a non-heat treatable and heat treatable aluminium alloys were welded as butt joints using friction stir welding technique. The welding parameters used were 1000rpm for rotational speed and 100mm/min for transverse speed. Three different aluminium alloy grades i.e. AA1100, AA5083 and AA6061 were dissimilar joined into an AA6061-AA1100 and AA6061-AA5083. All welded joints were successfully produced without defect at outside and inside the welded region. The different mixing patterns were observed in the stirred zone due to the different materials flow eventhough using the same parameter. The dissimilar joints exhibited very high joint efficiency with tensile strength close to the strength of AA6061 base metal. In particular, the ultimate tensile strength of AA6061-AA5083 and AA6061-AAI100 welded joints were 97% and 80%, respectively. Therefore, the dissimilar friction stir welding of aluminium alloys successfully possess strength of more than 80% of the base metal.