Analyses of tensile, fatigue crack growth and corrosion properties of dissimilar welded AA6061-T6/AA5083-H112 joints fabricated by GMAW and FSW: A comparison

In engineering design, the application of dissimilar metal weld (DMW) joints is sometimes unavoidable due to engineering and economic considerations. In this investigation, dissimilar AA5083-H112/AA6061-T6 aluminum alloy plates were joined using gas metal arc welding (GMAW) and friction stir welding (FSW) and their weld performances were compared in terms of weld microstructure, strength, fatigue and corrosion. Both welding processes were carried out using optimum welding parameters as reported previously. Results indicated that the weld nugget zone (WNZ) microstructure of the dissimilar FSW joints was characterized by the formation of fine grained equiaxed structure with some unmixed regions were observed. In contrast, a complete material mixing was found in the weld metal zone of the dissimilar GMAW joints with the microstructure was mainly coarse dendritic structures. The tensile strength of the dissimilar FSW joints could attain 175.1 MPa which was 51.0 % lower than that of AA6061-T6 base metal whereas the strength of the dissimilar GMAW joints was higher. In the dry atmosphere, the fatigue crack growth resistances of both dissimilar FSW and GMAW joints were competitive. In corrosive environment, however, the dissimilar FSW joints showed better fatigue performance which could be attributed to the weld microstructure, corrosion and residual stress.