Experimental and Theoretical Analysis of Deep Penetration Welding Processes with Low-Power Laser-Assisted Plasma Arcs

• Applicants: Professor Dr.-Ing. Eckhard Beyer; Professor Dr.-Ing. Uwe Füssel
• Subject Area: Production Automation and Assembly Technology
• Term: from 2015 to 2019
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 263050501

This research project aims at the further improvement of our current knowledge about laser-assisted plasma arc welding processes with particular consideration of the experimentally verified deep penetration effect at low laser beam intensities and low arc currents. Firstly, the processing conditions are to be identified by means of bead-on-plate welding trials for different types of metals such as iron, aluminum, magnesium, titanium or their alloys. Secondly, it is intended to reveal the most relevant interaction mechanisms being responsible for the transfer into the deep penetration welding regime by particular experimental and theoretical approaches. For the first time, new research hypotheses, concerning possible changes of the energy transfer efficiency and of thermal and fluid-mechanical interactions during laser-assisted plasma arc welding, will be verified. This involves investigations of beam absorption, arc root formation and preheating effects under conditions of deep penetration welding. Furthermore, the impact of changes in ambient pressure distribution and local flow fields, induced by the arc flow in interaction with laser-induced evaporation processes, on the deep penetration effect are to be characterized. A self-developed coaxial arrangement of the laser beam and the plasma arc, which directs the laser beam through a thin hollow tungsten cathode, will be applied for the laser-assisted plasma arc welding trials. In addition, different experimental setups are designed for detailed investigations of possible interaction phenomena. Adapted numerical simulation models support the evaluation of effects that cannot be directly observed by experimental methods. As a result, the most important interaction mechanisms in laser-assisted plasma arc welding will be identified. With the improved process understanding, guidelines for optimal parameter settings for laser-assisted plasma arc welding can be derived, depending on the particular properties of the material being welded.

• DFG Programme: Research Grants