Electron Beam Based Additive Manufacturing of Alloy 247 for Turbine Engine Application: From Research towards Industrialization

Abstract

In this contribution it will be shown how the metal powder bed fusion technology electron beam melting (EBM) enables a successful crack- and defect-free processing of the non-weldable Ni-based superalloy Alloy 247. Besides a defect-free processing, EBM process capabilities offer unique opportunities to tailor the microstructure according to material requirements for high-temperature applications. It could be demonstrated that EBM material properties are comparable or even better than traditionally casted Alloy 247 material. Tailored polycrystalline and columnar microstructures were achieved by process parameter adoption for solidification control. The EBM as-built microstructure was characterized by conventional metallography techniques and the results were used to define an adopted HIP + heat-treatment cycle which was applied prior to mechanical testing. Thus, corresponding mechanical and microstructural properties in different conditions will be presented and discussed to show EBM material capabilities. As a result, directionally solidified (DS) EBM material can achieve similar creep performance as DS cast material, despite an observed fine-grained “micro-DS” structure in EBM.Graphical