Experimental investigation on friction stir welding of dissimilar aluminium alloys

In current research work, dissimilar aluminium alloys such as AA5083, AA6081, AA6082, and AA7039 are butt joined by employing friction stir welding (FSW). The present study explores the effect of material positions of aluminium alloys (i.e., advancing side (AS) and retreating side (RS)) on the mechanical and metallurgical properties of FS welded dissimilar aluminium joints. The performance characteristics of the present study are analyzed in terms of mechanical and metallurgical properties. It is concluded that maximum strength is obtained for all the joints in which higher strength aluminium alloy is placed on the AS ((i.e., 386 MPa for AA7039-AA5083, 343 MPa for AA7039-AA6082, 320 MPa for AA5083-AA6082, and 225 MPa for AA6082-Aa6061). Furthermore, two types of macrostructures (i.e., banded and an onion ring) are observed at the nugget zone (NZ) of all the welded joints during metallurgical analysis. Besides this, energy-dispersive X-ray spectroscopy (EDS) analysis at NZ of FSW joints is also carried out to find out the chemical composition at NZ. It is observed that the key element of AS material is high er in weight percent as compared to RS at NZ. Moreover, tensile fractured surface locations are also analyzed to understand the process better. It is witnessed that most joints are fractured at heat affected zone (HAZ) on the lower strength material side.