Investigation on the Laser-Powder-Interaction when Applying Beam Shaping for DED-LB/M.

• Applicant: Dr.-Ing. Dominic Bartels
• Subject Area: Primary Shaping and Reshaping Technology, Additive Manufacturing
• Term: since 2026
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 572278035

Laser metal deposition, often also referred to as Directed Energy Deposition of Metals using a Laser Beam (DED-LB/M) is a generative manufacturing process that enables the production of near-net-shape components. One or more powderous materials are fed into the process zone where they are melted using a high-power laser. Modern laser beam sources allow the use of customised beam profiles or intensity distributions, which can influence the energy input and thus the temperature fields in the to-be-manufactured body or the substrate. This makes it conceivable, for example, to expand the material portfolio for the DED-LB/M to include difficult-to-weld material systems. The challenge here, however, is that the interaction of the laser beam with the powder material can lead to an undesired change in the intensity distribution arriving at the workpiece’s surface and thus the desired temperature fields. The aim of this project is therefore the fundamental investigation of the laser-powder-interaction when using beam shaping for DED-LB/M. Initially, the formation of the powder cloud will be investigated as a function of the powder feed parameters (mass flow, carrier gas flow) and the material used (particle size distribution, reflectivity). A high-speed camera setup is used for this purpose. This setup makes it possible to detect the caustics of the powder cloud and the particle distribution in it with high spatial and temporal resolution. This data will subsequently serve as the basis for the experimental and numerical analyses, which is used to investigate the interaction of the laser beam profile (geometry, intensity distribution within it) with the powder cloud. For the experimental tests, the laser beam is switched on and the intensity profile arriving at the beam-measuring device is recorded and compared with the initial profile. The attenuating or modifying effect of the powder cloud on the beam profile is initially detected for low laser powers. To describe the laser-powder-interaction, a ray-tracing model is also implemented, which can be used to predict the beam profile arriving at the workpiece as a function of the powder cloud parameters. In parallel, individual welding beads with and without powder and multi-layer components are generated and the resulting material properties are compared on a microscopic (including microstructure and microstructure) and macroscopic (hardness) level. At the same time, an inverse ray-tracing model is being developed based on the fundamental understanding of laser-powder-interaction. The aim of this model is to take into account the modifying effects of the powder cloud so that an intensity distribution required for subsequent material processing arrives at the workpiece’s surface. At the end of the project, a basic understanding on the interaction of arbitrary beam profiles with variable powder clouds in the DED-LB/M will be available.

• DFG Programme: Research Grants