Numerical simulation on an effect of backing plates on joint temperature and weld quality in air and immersed FSW of AA2014-T6

Abstract

In immersed friction stir welding (FSW), the workpiece is fully immersed in the water during welding. Thermal numerical model development of air and immersed FSW is carried out using three-dimensional heat transfer model. FSW joints were produced in AA2014-T6 plate using different backing plates like mild steel, asbestos, and copper in both air and immersed conditions. K-type thermocouples are used to measure the temperature profile at different locations on the workpiece during air and immersed FSW. Commercially available software ANSYS is used to develop thermal numerical model using temperature-dependent material properties of AA2014-T6. The coefficient of friction between a tool and plate has been considered constant throughout the analysis for the simplification for both air and immersed conditions. Simulation results obtained both for air and immersed FSW are in good agreement with those obtained experimentally. It is observed that diffusivity of backing plate affects the temperature of weld region. It is also observed that higher tensile strength and microhardness attained for the joints produced using mild steel backing plate in immersed FSW compared with other backing plates for the same weld parameters.