Numerical analysis and analytical modeling of the spatial distribution of heat flux during friction stir welding

The quantitative characterization of the in-process energy input during friction stir welding (FSW) is crucial for the prediction and the control of microstructure and properties in the welds. In this study, a novel CFD model is established to quantitatively investigate the spatial distribution of frictional heat flux and plastic deformation heat flux during the FSW of AA2024-T4, in which an advanced frictional boundary condition is used to capture the complex interplay between the spatial distribution of heat flux and the contact states at the welding tool/workpiece interface. It is found that the heat flux distribution is closely related to the contact states at the interface. An analytical model of the heat flux distribution is proposed based on the simulation results. The distribution of frictional heat flux at the welding tool/workpiece interface could be represented by a modified Gaussian heat source model and the distribution of plastic deformation heat flux at proximity of the welding tool could be represented by the Two - phase Hill function. The analytical model in this study provides a more realistic mathematical description of the heat flux distribution during FSW, which provides further support for the process optimization and thermal analysis of FSW.