Multiscale modeling of the onset of freckle formation during vacuum arc remelting

L. Yuan, P. D. Lee, G. Djambazov, K. Pericleous

    Research output: Chapter in Book/Report/Conference proceedingConference contributionpeer-review

    Abstract

    A multiscale model for the Vacuum Arc Remelting process (VAR) was developed to simulate dendritic microstructures during solidification and investigate the onset of freckle formation. On the macroscale, a 3D multi-physics model of VAR was used to study complex physical phenomena, including liquid metal flow with turbulence, heat transfer, and magnetohydrodynamics. The results showed that unsteady fluid flow in the liquid pool caused significant thermal perturbation at the solidification front. These results were coupled into a micromodel to simulate dendritic growth controlled by solute diffusion, including local remelting. The changes in Rayleigh number as the microstructure remelts was quantified to provide an indicator of when fluid flow channels (i.e. freckles) will initiate in the mushy zone. By examining the simulated microstructures, it was found that the Rayleigh number increased more than 300 times during remelting, which suggests that thermal perturbation could be responsible for the onset of freckle formation.

    Original languageEnglish
    Title of host publicationLMPC 2009 - Proceedings of the International Symposium on Liquid Metal Processing and Casting
    Pages39-46
    Number of pages8
    Publication statusPublished - 2009
    EventInternational Symposium on Liquid Metal Processing and Casting, LMPC 2009 - Santa Fe, United States
    Duration: 20 Sept 200923 Sept 2009

    Conference

    ConferenceInternational Symposium on Liquid Metal Processing and Casting, LMPC 2009
    Country/TerritoryUnited States
    CitySanta Fe
    Period20/09/0923/09/09

    Keywords

    • Freckle formation
    • Multiscale modeling
    • Rayleigh number
    • Remelting

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