3D Characterization of the Columnar-to-Equiaxed Transition in Additively Manufactured Inconel 718

Title3D Characterization of the Columnar-to-Equiaxed Transition in Additively Manufactured Inconel 718
Publication TypeConference Paper
Year of Publication2020
AuthorsPolonsky AT, Raghavan N, Echlin MP, Kirka MM, Dehoff RR, Pollock TM
EditorTin S, Hardy M, Clews J, Cormier J, Feng Q, Marcin J, O'Brien C, Suzuki A
Conference NameSuperalloys 2020
PublisherSpringer International Publishing
ISBN Number9783030518349
KeywordsAdditive manufacturing, Microstructure, Solidification, Tomography

Additive manufacturing (AM) provides enormous process- ing flexibility, enabling novel part geometries and opti- mized designs. Access to a local heat source further per- mits the potential for local microstructure control on the scale of individual melt pools, which can enable local con- trol of part properties. In order to design tailored process- ing strategies for target microstructures, models predict- ing the columnar-to-equiaxed transition must be extended to the high solidification velocities and complex thermal histories present in AM. Here, we combine 3D charac- terization with advanced modeling techniques to develop a more complete understanding of the solidification pro- cess and evolution of microstructure during electron beam melting (EBM) of Inconel 718. Full calibration of existing microstructure prediction models demonstrates the differ- ences between AM processes and more conventional weld- ing techniques, underlying the need for accurate deter- mination of key parameters that can only be measured directly in 3D. The ability to combine multisensor data in a consistent 3D framework via data fusion algorithms is essential to fully leverage these advanced characteriza- tion approaches. Thermal modeling provides insight on microstructure development within isolated solidification events and demonstrates the role of Marangoni effects on controlling solidification behavior.