The effect of tool transverse speed on the properties of aluminum-steel dissimilar joint by friction stir welding

This present study aimed to create an Al6061-St52 dissimilar joint and investigate the effect of the transverse speed by the friction stir welding process. Welding aluminum to steel is rugged by fusion methods because of the formation of brittle intermetallic compounds (IMCs). Therefore, to designate optimal parameters, acceptable IMC thickness, and mechanical properties determined. This research carried out different three transverse speeds of 16, 40 and 85 mm/min (with a constant pin offset of 0.2 mm). Geometry of toolchr('39')s pin radius and height is 4mm and 1.8mm, respectively. In the transverse speed parameter, the highest ultimate tensile strength (UTS) of 200 MPa was obtained at 85 mm/min. According to the Energy Dispersive X-ray Spectroscopy results, an IMC layer formed in the joint interface. The heat input rate was calculated to designate the optimal parameters. In tensile specimens, fracture mainly occurred in the joints and within the aluminum stir zone due to the combination of thick IMC layer and steel fragments, respectively. The micro-hardness measurement results showed that at (85 mm/min) the hardness values were HV 75 in the aluminum stir zone and HV 315 in the AS vicinity of the interface region. This hardness value is much higher than the base metals (Aluminum base metal is an average of HV 53 and an average steel base metal of HV 245).