Abstract
The study aimed to investigate the mechanical and microstructural properties of friction-stir welding of cold-rolled aluminium 6082 T6. Aluminium materials are utilised in marine, structural, aerodynamics, and other applications. When joining this material for various applications, the joint's or weld's quality is crucial. The friction-stir welding (FSW) process was invented in 1991 by Thomas and his colleagues as a welding process with few defects.
In this study, the aluminium (Al) 6082 T6 material plates were strain hardened by the severe plastic deformation (SPD) technique cold-rolling method. Before being joined/welded together with the FSW technique, the samples were cold-rolled from 12 mm to 6 mm thickness. As-received aluminium and cold-rolled samples of the same dimension were joint with FSW process. Samples were prepared, cut, mounted, and polished. Both cold-rolled and as-received joint samples were characterised using Optical Microscopy (OM) and Scanning Electron Microscopy (SEM). For further analysis, Energy Dispersive Spectroscopy (EDS) was performed on the specimen to reveal the chemical composition of particles spotted under optical and scanning electron microscopy. The mechanical properties of FSW joint butts were evaluated by conducting tensile and hardness tests. The results show that reducing material by 50% with the cold-rolling process enhances mechanical properties, and it was reported to be 11% harder than the as-received material. The cold-rolled FSW joint becomes more ductile as compared to the as-received material joint with the same welding parameters. The rolled sample has a high hardness on the welded zone. Common FSW defects such as hooks identified on weld joints might have negatively influenced on mechanical properties of both samples. Accordingly, cold-rolling aluminium 6082 enhances the material's mechanical properties; however, the heat generated when joining the plates using the FSW technique reduces mechanical properties to approximately the same level as when joined with as-received materials.