A Multiscale 3D Model of the Vacuum Arc Remelting Process
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A three-dimensional, transient, multiscale model of the VAR process is presented, allowing novel simulations of the influence of fluctuations in arc behavior on the flow and heat transfer in the molten pool and the effect this has on the microstructure and defects. The transient behavior of the arc was characterized using the external magnetic field and surface current measurements, which were then used as transient boundary conditions in the model. The interactions of the magnetic field, turbulent metal flow, and heat transfer were modeled using CFD techniques and this “macro” model was linked to a microscale solidification model. This allowed the transient fluctuations in the dendritic microstructure to be predicted, allowing the first coupled three-dimensional correlations between macroscopic operational parameters and microstructural defects to be performed. It was found that convection driven by the motion of the arc caused local remelting of the mushy zone, resulting in variations in permeability and solute density. This causes variations in the local Rayleigh number, leading to conditions under which freckle solidification defects will initiate. A three-dimensional transient tracking of particle fall-in was also simulated, enabling predictions of “white spot” defects via quantification of the trajectory and dissolution of inclusions entering the melt.
KeywordsRayleigh Number Mushy Zone Molten Pool Crucible Wall Pool Shape
The authors would like to acknowledge the EPSRC grants EP/D505011/1, EP/D505003/1, and EP/D50502X/1 for project support. LY and PDL would like to acknowledge the assistance provided by the Research Complex at Harwell, which was funded in part by the EPSRC grant (EP/I02249X/1).
- 5.K.M. Kelkar, S.V. Patankar, A. Mitchell, O. Kanou, N. Fukada, and K. Suzuki: Computational Modeling of the Vacuum Arc Remelting Process Used for the Production of Ingots of Titanium Alloys, http://inres.com/assets/files/meltflow/VAR-Model_Ti-2007-Conference.pdf.
- 7.R. Woodside: MSc Thesis, Oregon State University, 2008.Google Scholar
- 11.Yuan L, Lee PD, Djambazov G, Pericleous K (2009) International Journal of Cast Metals Research 22(1–4):147-150.Google Scholar
- 18.The PHYSICA code, http://staffweb.cms.gre.ac.uk/~physica/.
- 20.B.G. Nair and R.M. Ward: Liquid Metal Processing and Casting 2009, Santa Fe, 20–23 September 2009, TMS, Warrendale, PA, 2009.Google Scholar
- 23.Clift R., Grace J.R. and Weber M.E. : Bubbles, Drops, and Particles, Dover Publications, Mineola, NY, 2005, p. 381.Google Scholar
- 27.Lee PD, Chirazi A, Atwood RC, and Wang W: Mat. Sci. Eng. A, 365(1-2), 57-65. 2004.Google Scholar
- 30.Clift R, Grace JR and Weber ME, Bubbles, Drops and Particles, Academic Press, 1978.Google Scholar