Material Flow Behavior of Refill Friction Stir Spot Welded LY12 Aluminum Alloy

摘要

A three-dimensional finite volume model was established by ANSYS FLUENT software to simulate material flow behavior of the refill friction stir spot welding (RFSSW) process. The RFSSW experiment was performed to validate the rationality of the simulation results. Simulation results show that the maximum velocity appears at the sleeve outer wall. The velocity becomes smaller as the increase of the distance to the tool walls. The material flow behaviors are verified by the cross section and microstructure of the RFSSW joint. Low flow velocity in the joint center leads to alclad concentration, which easily results in shear fracture. The sleeve plunge depth must be bigger than the upper sheet thickness in order to obtain joint with large bonding area. Both increasing the rotational speed and refilling speed accelerate the material flow while increasing the rotational speed is a more effective method.