A three-dimensional numerical simulation model for weld characteristics analysis in fiber laser keyhole welding

The weld geometry characteristics are highly related to the mechanical properties and performance of the joints. The top surface of the weld is often assumed as the flat surface during calculating the fluid flow in the molten pool and hence weld reinforcement is ignored among the geometric parameters. In this paper, a three-dimensional numerical simulation model is developed to investigate the characteristics of the weld generated in the fiber laser keyhole welding. The gas layer above the molten pool has been considered to simulate the top surface of the weld in the simulation model and the free surface shape of the keyhole is calculated by the volume of fluid method. The hybrid heat source model is determined by the analysis of weld bead characteristics. Based on the numerical simulation results, the evolution of the weld profile characteristics have been demonstrated and the results are adopted to estimate the shape and sizes of the generated weld bead. From the comparison, the simulated results of the weld bead agree well with that of experiments. Furthermore, weld beads formed under different process conditions are calculated and the errors between the simulated and experimental results are analyzed in details. (C) 2016 Elsevier Ltd. All rights reserved.