Keyhole Behavior During Spot Laser WeldingV. Bruyere , C. Touvrey , P. Namy 
 SIMTEC, Grenoble, France
 CEA DAM, Is-sur-Tille, France
The formation of porosities in spot laser welding depends on complex thermo-hydraulic phenomena. To understand and control these mechanisms, the COMSOL Multiphysics® software is used to model both the interaction and cooling stages of an isolated impact made with a Nd:YAG pulsed laser. The model is based on the Phase Field method in order to apprehend the evolution of the liquid-gas interface shape. To validate the model, numerical results are compared to experimental characterizations. At last, the mechanisms responsible for the formation of porosities are identified and the beneficial effect of the laser power control (pulse shaping) is demonstrated.