Additive manufacturing of single crystalline nickel-based components by electron beam based powder bed fusion (T12*)

• Subject Area: Materials in Sintering Processes and Generative Manufacturing Processes
• Term: since 2024
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 190389738

Electron beam based powder bed fusion (PBF-EB) allows the manufacturing of single crystalline (SX) specimens with well defined orientation. Homogenization treatment is completed after some minutes and the resulting properties are superior to conventional SX material produced by investment casting. The latter results from the unprecedented homogeneity of PBF-EB SXs. In addition, the basic mechanisms for PBF-EB SX formation and suitable process windows were identified in previous works. However, feasibility has been demonstrated using simple test samples, i.e. the concept has not yet been proven for larger parts or components. In addition, the prepared PFB-EB SX samples feature an SX core covered by a polycrystalline shell. Size and dimension of this PX shell is still too large and requires in this state of the art a significant amount of post-processing and a large overstock for a component. The aim of this project is to develop SX process strategies for complex geometries based on the knowledge gained and to apply them to real components. For this, process strategies have to be worked out how to transfer the SX process window for simple geometries on complex ones and how to reduce the thickness of the polycrystalline shell. In a first step, this will be performed within the digital realm by applying numerical simulation combined with multi-criteria optimization. The underlying criteria are deduced from our acquired knowledge of SX-formation. In a second step, these strategies are implemented as part of PBF-EB processes. For this, open, free programmable machines with full access to process control are absolutely necessary. In addition, the strategy must also be realistically implementable. In order to assess the latter, a very precise knowledge of the machine properties must be available, e.g. the jump accuracy as a function of speed, the beam diameter as a function of the beam power or how quickly the power can be regulated.

• DFG Programme: CRC/Transregios (Transfer Project)
• Subproject of: TRR 103: From Atoms to Turbine Blades - A Scientific Approach for Developing the Next Generation of Single Crystal Superalloys
• International Connection: Sweden
• Applicant Institution: Ruhr-Universität Bochum
• Business and Industry: Arcam AB
• Project Head: Professorin Dr.-Ing. Carolin Körner