Development of numerical simulation technique for laser welding

We have been developing numerical simulation technique for laser welding. This study present some results obtained recently on the improvements of simulation models and numerical procedures, experimental data for code validation and the results of comparison of experiments with numerical analysis. We added the surface evaporation model under boiling temperature and introduced the level-set method as accurate and low numerical diffusion tracking procedure. We extend our gas phase model as enable to treat multi species of gas and mutual diffusion process. Two kinds of experiment were carried out in this study for code validation. One is the experiment to observe the surface tension driven convective flow and the other is to confirm the threshold of laser power density to form the keyhole. In these experiments, 6 kW YAG laser is used in CW mode and test pieces of aluminum alloy A1050P are irradiated in an inert atmospheric box. We calculated the heat conduction type of welding using improved code based on the actual welding conditions including the surface tension and surface evaporating models. And we simulated a series of transient behavior of molten pool irradiated by high laser power density.