Numerical and experimental study of microstructural and mechanical evolutions in dissimilar friction stir welding of AA5083-O and AA6061-T6 aluminum alloys

In the present study, a rigid viscoplastic finite element model based on Lagrangian and remeshing methods was developed to simulate the dissimilar friction stir welding of AA5083-O and AA6061-T6 aluminum alloys. Then, a combination of Cellular Automata (CA) and Laasraoui Jonas (LJ) methods was used to investigate the microstructural evolutions of materials with regard to the thermo-mechanical conditions engaged in the process. Moreover, the point tracking method was used to evaluate the flow pattern of the material around the tool and the results were compared with experiment which the elongation and movement of the material towards the upper part of the advancing side was observed for the stirring and mixing of the material. By studying the dynamic recrystallization in the simulation, the simultaneous effect of temperature and severe plastic deformation on grain refining was investigated. The results of microstructural changes showed that with increasing Zener-Hollomon (Z) parameter, grain size decreases and changes the hardness and strength of the alloys used. Also in the mechanical test, the decrease in strength at the advancing side caused the samples become fractured from this side in the tensile test.