Today, steel to aluminum joints are used to facilitate traortation and fuel consumption. These joints are applied from nuclear, aerospace and naval to automobile and kitchen industries. According to previews studies, fusion welding processes are not suitable methods for these joints. Solid-state welding, especially friction stir welding, is proper for these joints. Friction stir welding is of the most applicable methods to join dissimilar metals. However, using this method for these two metals needs adequate prediction of temperature distribution and material flow to obtain enhanced joints. In this study, a finite element method is used to predict the temperature distribution. The heat produced during the joining of 304 stainless steel to 5083 aluminum alloy by friction stir welding method was simulated and the distribution of temperature was predicted by finite element method. Both, transient and steady-state (with and without infinite elements) thermal solutions were used in simulations and the two methods were compared correspondingly. To verify the models, two sheets of stainless steel and aluminum alloy were prepared and welded by friction stir welding. Additionally, by using thermocouples temperature history of different points on the sheets was obtained during welding. Then, the simulation and the experimental results were compared to validate the model. Finally, an Artificial Neural Network model was created and the effect of different process parameters on the maximum temperature was investigated. In addition, a computational fluid dynamics solution is coupled with the thermal solution. Therefore, the flow rate, strain rate and dynamic viscosity were obtained. The effects of welding parameters on material plastic flow and final properties of the weldment for friction stir welding interface is investigated. In order to predict the temperature distribution, a steady-state solution with infinite elements was used. Also to predict the interface morphology, Computational Fluid Dynamics (CFD) with Level Set method was used. It should be noted that computed results were verified using experimental results. It was concluded that by lowering rotational speed and movement of pin offset through aluminum, more continues material flow and proper weldments were obtained. Keywords: Friction stir welding, dissimilar joint, Finite element method, Thermal simulation, Computational fluid dynamics, Level set method, Morphology simulation.
