Self-consistent modelling of Laser- Activated -TIG (LATIG) welding of Aluminium or Copper

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For welding Aluminum and Copper, laser activated TIG welding (LATIG) represents a suitable process. It is based on the synergetic interaction of laser radiation and arc and offers a particularly high melting efficiency compared to the individual use of both processes. The physical phenomena and their interactions that are responsible for the increase in melting efficiency are not yet sufficiently understood. From a preliminary analysis it can be concluded that the influence of solid-state laser radiation on the TIG welding process is not gained due to a direct interaction of the laser radiation with the arc plasma but that the effects on the work piece surface needs to be considered. Therefore, in this project, a process model will be developed, implemented and used for numerical experiments, in order to analyse the influence of the laser on the efficiency of melting in the case of aluminium and copper. The main phenomenon to be taken into account is the anode sheath with considering the laser-induced evaporation, with the formation of a metallic vapour jet and its influence on the thermal, gas-dynamic and electromagnetic characteristics of the arc plasma, as well as on the current density, heat flux and pressure distributions on the weld pool surface. With the help of such model, the cause and effect chain of these interactions can be investigated and the role of the distinguished interactions can be evaluated. Special focus lies on one side on the effect of the formation of a metallic vapour jet on the thermal, gas-dynamic and electromagnetic characteristics of the arc plasma and its interaction with the work piece surface. On the other side, the model focusses on the dynamics of the weld pool free surface, heat transfer, hydrodynamic and electromagnetic processes in the weld pool taking into account the effects of laser evaporation (convective mode of evaporation) of metal on the anode boundary layer. The extended knowledge and understanding about the LATIG process allow the development of recommendations to achieve the high productivity and process stability for welding aluminium and copper.