Carbide Additivation to Hot Working Tool Steel by an Optimized Satelliting Process with Pectin Binder

• Applicants: Professor Dr.-Ing. Christoph Broeckmann; Professor Dr. Andrij Pich
• Subject Area: Materials in Sintering Processes and Generative Manufacturing Processes
• Term: since 2024
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 539485538

Recently, a process referred to as "satelliting" was introduced in the feedstock preparation for additive manufacturing processes. Small satellite particles are bonded to larger parent particles in order to avoid demixing within a multi-component powder feedstock. The feasibility of the use of polysaccharide pectin as a bonding agent instead of synthetic polymer PVA in the satelliting method for PBF-LB/M processing of tool steel was previously demonstrated. The results have shown improved chemical homogeneity using the satelliting technique with a 2% binder amount. The additivated alloy showed a promising martensitic microstructure after subsequent heat treatment. However, unresolved questions include the potential of different pectin types for improved properties, reducing carbon pickup from the binder, and the influence of alloy composition and processing on microstructure and mechanical properties. This project has two main objectives: The first objective is to investigate how the chemical structure and molecular weights of different pectins affect their binding effectiveness to various surfaces. Further, the most suitable drying process for powder particles with adhesive polymers will be determined. Both spray drying and fluidized bed processing will be evaluated and compared using the selected pectin samples. The second main objective is to comprehend how the optimized satelliting process impacts the mechanical properties of alloys processed using PBF-LB/M. The study aims to link carbon pickup to binder content, shifted martensite transformation temperatures, and alloy properties. A direct comparison with pre-alloyed atomized tool steels of the same compositions is planned to assess the binder's influence on the processed materials. An additional reference of a conventionally processed tool steel will be included for benchmark purposes. Static bending strength and fatigue resistance of the reference materials and the alloy from satellited powder will be characterized. This analysis will provide insights into mechanical properties as well as fatigue mechanisms and crack initiation. Through this comprehensive approach, the project aims to improve the satelliting technique's effectiveness in alloy production, from understanding surface binding to enhancing processability and evaluating resulting mechanical properties.

• DFG Programme: Research Grants