Manipulating local heat accumulation towards controlled quality and microstructure of a Co-Cr-Mo alloy in powder bed fusion with electron beam

Controlled forming quality and solidification microstructure are crucial issues for the application of additive manufactured metal. The local heat accumulation through a line order hatching strategy was considered when a Co-28Cr-6Mo alloy was fabricated by powder bed fusion with electron beam. The study revealed that by weakening the local heat accumulation, overheating as a source of unevenness was easily avoided. Transient geometry of the molten pool and associated temperature gradient direction were determined by the local heat accumulation, which subsequently alters the solidification microstructure. The numerical simulations were performed to clarify the mechanisms involved. (C) 2019 Elsevier B.V. All rights reserved.