Numerical Simulation Of Temperature Fields And Plastic Materials Flow In Friction Stir Welding Of 2A12 Aluminum Alloy

Friction stir welding (FSW) is a relatively new solid-state joining process. This joining technique is energy efficient and environment friendly. Temperature fields and the material flow behaviors are of critical significance for optimizing welding parameters and ensuring weld quality in FSW process.Good joint can be got by appropriate selecting the process parameters,such as axial force, rotation speed and welding speed in FSW of 2A12 aluminium alloy. The samples's microstructures in weld nugget zone(WNZ), thermo-mechanically affected zone(TMAZ), heat affected zone(HAZ) and base material zone(BMZ) are analyzed. Copper alloy bars are inserted into different locations of 2A12 aluminum alloy plate to demonstrate actual plastic material flow in FSW.Using the finite element analysis software the temperature fields is analyzed in FSW process. An appropriate heat generation model is established to consider the frictional heat between the shoulder and workpiece and interacting of pin and workpiece. The results of temperature fields of numerical simulation are compared with the experimental results, and the results show that both are in agreement.Fluid dynamic theory is used to develop a mathematical model for material flow in FSW process. Continuity equation, momentum equation and energy equation are used to describe the plastic material flow in FSW process. The mass flow is treated as a flow of a non-Newtonian, incompressible, visco-plastic material during the simulation, passing a rotary threaded tool as laminar flow. The simulation results show that the materials in both the advancing side(AS) and retreating side(RS) all flow only past the pin on the RS. Rotation speed has great effects on the flow of plastic material. With the rotation speed increases, the size of TMAZ also increases. Welding speed is not obvious in affecting TMAZ size.