Optimization of tensile properties by rotary friction welded dissimilar 2014 T6 and 6082 T6 aluminium alloys

Sub-melting temperature bonding has the advantages of joining ferrous and non-ferrous material with a lack of filler metal, flux, shielding gas and shorter welding periods, allowing dissimilar welding. This research examines the impact of varying friction pressure (FRT), forging pressure (FP), and friction time (FT) on the rotary friction welding of dissimilar 6082 T6/AA2014 T6 aluminium alloy rods with a diameter of 18 mm. The parameters are optimized to enhance the tensile strength using the design of experiments technique of Taguchi L9 orthogonal analysis coupled with analysis of variance. The study examines the relationship between microstructural characteristics and mechanical properties, including tensile strength and microhardness. The friction pressure and forging pressure were the dominant factor influencing the tensile strength having joint efficiency of 89.54%. Extreme grain growth and recrystallization due to heat accumulation on the AA6082 side result in elongated grains adjacent to the interface, with the TMAZ grains of the rotating side being coarser than those of the AA2014 stationary side in the S6 specimen. Maximum tensile strength of 291 MPa and impact strength of 119 J were observed in the S6 specimen, which exhibited ductile failures with dimple structures in the fracture zone. The hardness in the weld zone was higher than the base metal indicating stronger bonding in the weld zone and weaker bonding in the TMAZ where the fracture occurred. The analysis showed that the S6 specimen with FRT of 90 MPa, FP of 100 MPa and FT of 22 s was the optimum parameter to enhance the tensile strength.