Development of Novel Duplex Stainless Steels for Laser-Based Additive Manufacturing (PBF-LB/M) with In-Situ-Formed Fine-Grained Ferritic-Austenitic Duplex Structure

• Applicants: Professor Dr.-Ing. Andreas Bührig-Polaczek; Professor Dr.-Ing. Ulrich Krupp
• Subject Area: Materials in Sintering Processes and Generative Manufacturing Processes ; Mechanical Properties of Metallic Materials and their Microstructural Origins
• Term: since 2024
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 547493296

Tailoring the microstructure of alloys during laser-based additive manufacturing (AM) remains a severe challenge given the repeated cyclic temperature input accompanied with high, locally varying cooling and re-heating rates. In this context, simultaneous adaption of alloy composition and AM process parameters plays a crucial role. In this research project, we aim to understand the fundamental liquid-solid and solid-solid phase transformations that govern the microstructure evolution. Novel duplex steels with in situ formed ferritic-austenitic (approx. 50%-50%) grain structures will be developed. In addition to computational alloy design, specimens will be produced via vacuum inert gas atomization (VIGA) and subsequent laser-beam powder bed fusion (PBF-LB/M) experiments. The focus of the project will be put on efficient use of added or precipitated particles with high melting point to promote heterogeneous nucleation during solidification. By strongly increasing the nucleation rate in the undercooling regime, epitaxial growth will be impeded. The influence of the resulting multi-phase, fine-grained, equiaxed microstructure on the mechanical and corrosion properties will be investigated, understood and used to design novel duplex steels for AM.

• DFG Programme: Research Grants
• Co-Investigators: Professor Dr.-Ing. Christian Haase; Dr.-Ing. Iris Raffeis