Research On Friction Stir Welding Of 5083 Aluminum And Its Finite Element Simulation

Friction stir welding is a relatively new solid joining method. In this paper 3.5mm thickness 5083-H321 aluminum alloy was joined by friction stir welding. The joints were well formed when parameters were proper. The highest joint strength without any treatment after welding could reach to 93.6% of that of base material, and the joints could reach to 180° without any cracking when face and root bending test. But the void defect was produced when the parameters were not proper, and the tunnel defect appeared when the parameters got worse. The condition of joint without void defect was the heat input should higher than 569.72J/mm.The void defect changed to tunnel defect when the heat input was lower than 146.95J/mm.The measurement and analysis of torque during FSW allowed for improved tool and FSW equipment designs, especially for joining of higher temperature materials such as Ti, Ni and steel alloys. Second, this signal could be used for control of FSW process in real-time. Keeping the torque constant was helpful for obtaining a uniformity quality joint when welding achieved a steady state. Finally, this information could serve as verification for process models. The torque in real-time of motor was measured by torque sensor in this paper. The result showed that the torque almost kept constant when welding came to quasi-steady state.Microstructure of friction stir welded 5083 aluminum alloy joints were analyzed and the results showed that the upside zone of the joining showed itself as a crown shape, and the mid-side and downside was a deposit zone of weld nugget. A ring microstructure could be seen in the nugget of joining. The weld nugget suffered dynamic recovery and recrystallization caused by the intense thermo-mechanical effect, and gained fine and equiaxed grains. The weld transition zone also suffered thermo-mechanical effect, but the dynamic recrystallization didn't occurred due to insufficiency of deformation strain. Therefore the structure grains showed itself as a high deformation structure. The purlieu between weld nugget zone and transition zone in advancing side was more obvious than which in retreating side.The thermal model of FSW process was established. The heat input of plunge, dwell and welding phase were calculated by torque, and the temperature field of each phase was simulated using the thermal model. The result of simulation showed that...