Scanning Strategies in Electron Beam Melting to Influence Microstructure Development

Recent advances with the use of electron beam melting (EBM) additive manufacturing (AM) have indicated the ability to control the resultant microstructure based on control of the processing parameters. An Arcam A2 EBM system was utilized to control the size of the microstructure for Ti-6Al-4V components. The methodology employed allowed to refine the microstructure at selected regions of a part while maintaining a more typical acicular α+β microstructure in the rest of the components. This process was achieved by partitioning the layer data into two files that enabled different scanning conditions during fabrication. The first scan consisted of hatching of the component geometry (circle with dimensions of 15mm in diameter) excluding a center circle with dimensions of 1mm in diameter. Following the first scan, a pointwise melting for the center circle was completed. The strategy generated a finer structure in the center circle in comparison with the more regular sized microstructure in the rest of the build. Components built were sectioned and prepared into metallographic specimens that were observed through optical microscopy. The micrographs were used to measure the length and width of alpha laths.Mechanical Engineerin