Process Mapping of Ti-6Al-4V Solidification Microstructure Across Two E-Beam AM Processes

In direct metal additive manufacturing (AM), the ability to predict and control as-deposited microstructure can reduce post-processing and speed qualification.  In this work, modeling and experimental results are presented for Ti64 prior beta grain size and morphology for two direct metal AM processes:  Electron Beam Melting (EBM) by Arcam and Electron Beam Freeform Fabrication (EBF³) from NASA Langley.  Both EBM and EBF³ use electron beams in a high vacuum environment. The EBM process is conducted in a powder bed.  EBF³ is a wire feed process operating within a very different region of processing space.  For each process, methods for maintaining microstructural features across process variables are identified as are ranges of prior beta grain sizes.  Comparisons are then made between the processes to identify common traits and ranges of microstructural features available across the entire direct metal AM processing space.  Results for this talk are for single bead deposits but methods are identified for extension to other geometries.