Prospects in the application of active energy filtration for the management of electron beam powder bed fusion processes.

In recent years, Electron Beam Powder Bed Fusion (EB-PBF) Additive Manufacturing (AM) has grown from a niche technology operating in a limited application space to a capable and effective tool for manufacturing using crack prone alloys, refractory metals, and copper for a great variety of applications. The primary challenge facing EB-PBF as a methodology is that bespoke part qualification relies on nondestructive methods of evaluation such as X-ray micro-computed tomography. The cost of this qualification, however, often exceeds that of the build itself, which limits the ability of EB-PBF to be applied in situations where low to single-unit batch sizes are required, which is a demand that it is particularly suited to fill as a manufacturing methodology.

By nature, EB-PBF enabled novel strategies making use of localized control of part heating, cooling rates, and solidification conditions, which allows for precise control over outcomes such as solidification, microstructure, and crystal orientation. This introduces new design capabilities, as microstructure is vital in determining the mechanical performance of a part. The only current means to validate the created microstructure, however, is through the use of destructive methods such as Electron Backscatter Diffraction. This renders the part useless and is impractical for the production of custom pieces.

Our recent work has explored a quantitative approach to the use of the energy profiles of backscattered, secondary, and thermionic electrons generated within the printing process in order to enhance the level of detail in the information which these emissions can provide about the part during the printing process. The capabilities of this method to assess the in situ thermal and microstructural can provide information which would be critical to the non-destructive qualification of printed parts.