The reaction of metallic melts during laser beam welding under microgravity

• Applicant: Professor Dr.-Ing. Stefan Kaierle
• Subject Area: Joining and Separation Technology
• Term: since 2021
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 492053502

The objective of this research project is to determine basic knowledge about the influence of microgravity on the melt for the laser beam welding process, especially with regard to the interaction of the melt with the laser radiation and the resulting melt pool dynamics. The topic is initially investigated under earth gravitation as a reference. The experiments under microgravity are carried out using the large-scale research device Einstein-Elevator.The effects of gravity on manufacturing processes and especially on the melt pools are examined. For heat conduction and deep penetration welding processes, flow characteristics, mixing, melt pool characteristics and the resulting weld seam shape for similar and dissimilar joints are investigated. Furthermore, the increased influence of surface tension on the weld pool under microgravity is considered. Starting with bead on plate welds, joint welds (lap and butt joints) are also studied. For laser beam deep penetration welding, the influence of gravity on the formation and stability of the keyhole as well as the shape of the weld root is analyzed in addition.To carry out the research work introduced, the system technology and the experimental setup will be designed with regard to the loads occurring during the drop tower tests concerning robustness and stability. The system will be adapted to the boundary conditions.As a first idea for answering the question "Under which conditions a joining production process in space is feasible?”, a gain in knowledge regarding the influence of significantly reduced gravity on the laser beam welding process is provided.

• DFG Programme: Research Grants
• Major Instrumentation: Faserlaserstrahlquelle 2 kW, Lichtwellenleiter 100 μm, Bearbeitungsoptik
• Instrumentation Group: 5700 Festkörper-Laser