Formation Of Porosities During Spot Laser Welding : Case Of Tantalum Joining

C. Touvrey
CEA Valduc, France

During the welding of tantalum with a ND: YAG pulsed laser, a deep and narrow cavity, called the keyhole, is formed. At the end of the process, surface tension forces provoke the collapse of the keyhole. For important interface deformations, gas bubbles can be trapped into the melting pool. If the solidification time is insufficient, these bubbles give birth to residual porosities. The aim of the study is to predict the porosities diameters depending on the keyhole shape with the help of COMSOL Multiphysics. The level set method has been first used to compute the dynamics of the interface position during the keyhole collapse. A comparison with the phase field method has then been performed for particular conditions.