Mechanisms of capillary and weld seam formation in laser and electron beam welding (Capillary Twins)

• Applicants: Dr.-Ing. Christian Hagenlocher; Dr.-Ing. Simon Olschok
• Subject Area: Joining and Separation Technology
• Term: since 2025
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 571456669

The aim of the research project is to gain insights into the mechanisms of capillary formation and their influence on the resulting weld seams in laser welding (LBW) and electron beam welding (EBW). The focus is on investigating the comparability of the two processes, starting with the similarity of weld seams under identical parameters and, derived from this, the comparability of the capillaries. The in-situ recording of the capillary geometry of the two different processes is carried out on the one hand by X-ray internal reflection in EBW and on the other hand by radiography in LBW. The optimisation of the measurement technology for more precise recording of the capillary geometry forms the basis for increasing process understanding. Based on the findings on the comparability of the capillaries and weld seams, the existing models of the energy transport mechanisms within the capillaries for both beam welding processes are reviewed. This will provide insights into the transferability of process parameters between the processes: It must be investigated whether energy is transferred from the capillary front to the capillary rear wall in EBW and how great the influence of multiple reflection is on capillary formation in LBW. The comparison of energy transport and multiple reflection is carried out on different materials whose varying optical and physical properties make it possible to validate and adapt the theories on capillary formation. Appropriate experiments and analyses are intended to provide a more comprehensive understanding of the processes in order to significantly improve the weld seam quality and exploit the full potential of the two beam welding processes.

• DFG Programme: Research Grants