Thermohydraulic modeling of pulsed laser welding

The major aim of this study is to increase our understanding of the link between operating parameters and thermo-hydraulic evolution in the welding area, in the case of an isolated impact made with a Nd:YAG pulsed laser on a thin Ti6Al4V sheet. Two numerical approaches are used to model both the interaction stage and the cooling one. During the interaction, the free surface behavior is precisely described by a moving mesh method (ALE method). The dependence between the interface temperature and the recoil pressure is discussed and a simplified approach is used. The keyhole collapse and the cooling stage are modeled by the phase field method (Eulerian method), which enables to consider the behavior of the gas trapped into the melting pool. Numerical calculations are compared to experimental characterizations (melted zone shape and defects position), in the case of relatively low laser power (inferior to 1000 W).