Welding of Dissimilar A5754-A5083 and A6061- A6082 Aluminium Alloys for Automotive Applications

Abstract

In the present study, dissimilar aluminium alloy combinations A6061 T6-A6082 T6 and A5754 H111-A5083 H111 were welded using the cold metal transfer (CMT), tungsten inert gas (TIG) welding and friction stir welding (FSW) processes. Each dissimilar combination was welded by two different fillers, such as ER4043 and ER5356, in CMT and TIG. Since FSW is a solid-state welding process, no filler materials were used. The miniature tensile samples were extracted from the interface regions of the TIG and CMT welded joints and the stir zone (SZ) of the FSWed joint. The TIG and CMT welded alloys' individual interface microstructure has been correlated with mechanical properties. The SZ of FSWed parts is of prime importance because this zone primarily decides the resulting property of the welded joint. Therefore, the microstructural features and mechanical properties of the SZ in the FSWed joints have been investigated in detail. The tensile properties of the overall weld region samples have been determined using macro-tensile testing samples. The dissimilar A6061-T6 and A6082-T6 joints welded by CMT and TIG welding processes using two different fillers (ER5356 and ER4043) exhibited higher strength in the A6082 interface in comparison to the A6061 interface. When the dissimilar A5754 and A5083 alloys were welded by CMT and TIG welding processes using two different fillers (ER5356 and ER4043) fillers, the interface region of the A5083 side exhibited higher strength than the interface region of the A5754. In the FSWed joints, the refined grain structure in SZ increased the hardness and strength. The overall joint tensile properties of the dissimilar joints are essential for identifying a suitable welding process to join A6061-A6082 and A5754-A5083 dissimilar alloys. Among the A6061-A6082 dissimilar joints, the CMT joint produced by ER5356 filler and the FSW joint exhibited higher tensile properties than the other joints. The tensile properties of the A6061-A6082 dissimilar CMT joint produced by ER5356 filler and the FSW joint are nearly the same. However, the FSW process does not use any shielding gas, filler materials, and the surface preparation is also not critical for the process. These factors can play a vital role to reduce the cost of welding effectively. Also, the FSW process is environment friendly, due to the absence of fumes and shielding gases. In the case of A5754-A5083 dissimilar joints, the FSW joint shows higher tensile properties than the other joints. Therefore, the FSW process can be recommended as the preferable joining method among all the investigated processes.