Analysis of The Main Hydrodynamic Mechanisms in Laser Induced Keyhole Welding

Adequate modeling of additive laser technologies and laser welding requires a comparative analysis of the main hydrodynamic mechanisms and modes. The melt hydrodynamics during laser processing can be generated by the vapor recoil pressure and the thermocapillary effect. Analysis of the measured values of melt flow velocity at the front wall of keyhole and other measured parameters accompanying the welding allows to reveal the role of each mechanism. It is shown that the hydrodynamics in this case are determined by the thermocapillary shear flow in the thin surface layer at the negligible evaporation.