Benchmark Study of Thermal Behavior, Surface Topography, and Dendritic Microstructure in Selective Laser Melting of Inconel 625

Zhengtao Gan, Yanping Lian, Stephen E. Lin, Kevontrez K. Jones, Wing Kam Liu*, Gregory J. Wagner

*Corresponding author for this work

Research output: Contribution to journalArticle

17 Scopus citations

Abstract

In the NIST additive manufacturing benchmark (AM-Bench) experiments, melt pool geometry, cooling rates, surface topography, and dendritic microstructure in laser melted Inconel 625 were used to challenge and validate computational models of the melting and solidification process. To this end, three thermal models incorporating different physics are compared with the experimental data. It is identified that the heat convection enhanced by the thermocapillary flow inside the melt pool and heat loss caused by vaporization play pivotal roles to guarantee the accuracy of the predictions, and thus should be considered in the thermal model. Neglecting fluid flow and vaporization leads to nearly 100% difference in cooling rate during solidification, and 20% difference in cooling rate after solidification from the results. With the most accurate thermal model, surface topographies of the melt tracks are predicted and quantitatively analyzed. Using the Kurz-Fisher model, the primary dendrite arm spacing is predicted based on the thermal gradient and solidification rate predictions, while elemental segregation is predicted using the Scheil-Gulliver model and a non-equilibrium solidification model. Additionally, it is shown that increasing scan speed inhibits elemental microsegregation.

Original languageEnglish (US)
Pages (from-to)178-193
Number of pages16
JournalIntegrating Materials and Manufacturing Innovation
Volume8
Issue number2
DOIs
StatePublished - Jun 15 2019

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Keywords

  • Additive manufacturing
  • Cooling rate
  • Dendrite arm spacing
  • Fluid flow
  • Microsegregation
  • Ni-based superalloy

ASJC Scopus subject areas

  • Materials Science(all)
  • Industrial and Manufacturing Engineering

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