Application of the phase field model towards selective laser melting of Inconel 718, through an integrated multiscale framework

Authors
Peters, Scott
ORCID
Loading...
Thumbnail Image
Other Contributors
Sundararaman, Ravishankar
Duquette, David J.
Maniatty, Antoinette M.
Lewis, Daniel
Issue Date
2021-12
Keywords
Materials engineering
Degree
PhD
Terms of Use
Attribution-NonCommercial-NoDerivs 3.0 United States
This electronic version is a licensed copy owned by Rensselaer Polytechnic Institute (RPI), Troy, NY. Copyright of original work retained by author.
Full Citation
Abstract
The Selective Laser Melting (SLM) process is a developing additive manufacturing process for metals. This technique allows for very fine details to be produced with minimal post-processing required, and is especially useful for creating parts from traditionally hard-to-manufacture materials, such as Inconel 718. For this technique to mature, a link between the thermal conditions within the SLM process and the final microstructure must be established. In our work, we have used a thermal field for a set of known print parameters from the literature, provided to us by collaborators, to drive the evolution of a multicomponent phase field model approximating that of Inconel 718. Using the frozen gradient approximation, the solidification of γ-FCC dendrites in the liquid melt is observed, and values for primary dendrite arm spacing (PDAS) and composition are computed. In addition, the potential for secondary phase formation is evaluated through the measurement of the free energy of formation of secondary phases at characteristic points in the simulation. Finally, we develop an analytic model, taking certain approximations, demonstrating that as thermal gradient increases, a larger range of dendrite widths can exist at steady state. We also show how grain orientation plays a role in selecting the observed PDAS, as dendrite spacing will tend to be determined by the characteristic dendrite width formed through the tertiary arm branching process. Our work demonstrates that multicomponent phase field simulations of the primary solidification of Inconel 718 in the SLM process are feasible to conduct, and that with future work to improve the quantitative accuracy of the model, increasingly accurate results can be obtained from simulation. As this model is composition-ambivalent, this technique can lead to the the production of new, SLM-optimized alloys, testing their performance in silico before they are ever manufactured.
Description
December 2021
School of Engineering
Department
Dept. of Materials Science and Engineering
Publisher
Rensselaer Polytechnic Institute, Troy, NY
Relationships
Rensselaer Theses and Dissertations Online Collection
Access
CC BY-NC-ND. Users may download and share copies with attribution in accordance with a Creative Commons Attribution-Noncommercial-No Derivative Works 3.0 license. No commercial use or derivatives are permitted without the explicit approval of the author.