In this paper, the friction stir welding (FSW) technique was used to create dissimilar alloy joints of AA6061-AA5083, and dissimilar material joints of AA6061-S235JR mild steel. Joints were fabricated by a conventional belting milling machine. Plates of 5 mm thickness were welded in a butt joint configuration. The joints were evaluated by extracting tensile testing specimens to study the failure strength at different rotational speeds. Tunnel defects were formed under certain parameters and changing the parameter values had different effects on the tunnel defects depending on the type of dissimilar joint welded. Vickers micro hardness measurements were taken on cross sections of welded joints to study the hardness pattern across the weld zones.
