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Additive manufacturing of nickel-based superalloy Inconel 718 by selective electron beam melting: Processing window and microstructure

Published online by Cambridge University Press:  11 August 2014

Harald Ernst Helmer ,
Carolin Körner  and
Robert Friedrich Singer
Harald Ernst Helmer*
Affiliation:
Zentralinstitut für Neue Materialien und Prozesstechnik (ZMP), University of Erlangen-Nuernberg, Fürth 90762, Germany
Carolin Körner
Affiliation:
Department of Materials Science, Chair of Metals Science and Technology, University of Erlangen-Nuernberg, Erlangen 91058, Germany
Robert Friedrich Singer
Affiliation:
Department of Materials Science, Chair of Metals Science and Technology, University of Erlangen-Nuernberg, Erlangen 91058, Germany
*
a)Address all correspondence to this author. e-mail: harald.e.helmer@fau.de
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Abstract

Cube-shaped IN718 samples were produced by selective electron beam melting (SEBM) with varying beam power, deflection speed, and beam spot size. Process parameter windows were identified where fully dense samples are obtained with no surface unevenness. High deflection speeds were demonstrated to result in smaller demand of area energy. This result is explained by the reduced time for heat dissipation into the substrate during hatching. The grain structure was strongly affected by SEBM process parameters. Under certain conditions, epitaxial growth over many layers and well-developed columnar grain structures were obtained with a polycrystalline substrate plate. A more defocused beam led to a lower melt pool temperature and shallower melt pool geometry where maximum temperature gradients and solidification rates were more or less in parallel with the building direction and primary dendrite arm orientation. These conditions help to suppress grain nucleation ahead of the nucleation front as vigorous melt movement, fragmentation of dendrites, and tertiary arm growth are suppressed.

Type
Articles
Information
Journal of Materials Research , Volume 29 , Issue 17: Focus Issue: The Materials Science of Additive Manufacturing , 14 September 2014 , pp. 1987 - 1996
Copyright
Copyright © Materials Research Society 2014 

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