Production, characterization and simulation of TRIP/TWIP compositionally complex alloys produced by PBF-EB

• Applicants: Professor Dr.-Ing. Christoph Leyens; Professor Dr. Ingo Steinbach
• Subject Area: Materials in Sintering Processes and Generative Manufacturing Processes
• Term: since 2024
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 550329829

The aim of this project is the reproducible and local adjustment of the alloy composition of a Fe-Mn-Co-Cr "Compositionally Complex Alloy" (CCA) by means of electron beam powder bed fusion (PBF-EB). Due to the high entropy effects, CCA alloys often have unique combinations of properties, such as high oxidation,- corrosion resistance and very good mechanical strength, as well as high elongation. The reduction of the manganese content in Fe-Mn-Co-Cr CCA leads to a change in the stacking fault energy and thus exerts a considerable influence on the transformation mechanism taking place in the microstructure (TRIP or TWIP effect). This results in the possibility of setting an application-optimized property profile and graduated microstructures. Applying the phase-field method, the highly transient solidification process can be reliably simulated. Furthermore, the grain refinement is simulated by the martensitic γ-ε transformation during the thermal cycling in the building process and the heating and cooling phases, depending on the Mn content. To evaluate the results, the resulting samples are extensively analyzed in terms of materials science. In addition to a detailed microstructural characterization (e.g. using SEM, EBSD, XRD and CT), the mechanical properties are investigated using static test methods such as the tensile test and the hardness test. The aim is to gain initial insights into the interaction of different microstructure types. For this purpose, the feedback and comparison of the experimentally determined results in the simulation are of great importance.The synergetic combination of the investigations on the process microstructure property correlation by the TU Dresden and the simulative support by the Ruhr University Bochum will provide comprehensive knowledge on the adjustment of locally adapted microstructure variations and their effects on the mechanical properties. Furthermore, a fundamental understanding of the alloying process using PBF-EB is being developed.

• DFG Programme: Research Grants