Metallurgical and Materials Transactions B

, Volume 40, Issue 3, pp 281–288 | Cite as

Segregation Development in Multiple Melt Vacuum Arc Remelting

Symposium: Liquid Metal Processing and Casting

Abstract

A numerical model of the vacuum arc remelting (VAR) process was used to study multistage VAR processes. The studies of low and high power 3XVAR confirmed the results of the single stage process studies for Ti-10-2-3: (1) high arc power results in strong electromagnetically driven flow and undesirably high macrosegregation; (2) low arc power does not generate significant Lorentz forces and the flow is dominated by weaker buoyancy forces, which cause less segregation; and (3) even short-lived changes in process conditions during the run may result in a switch of the flow regime in low power cases from buoyancy driven to electromagnetically driven. The switch of flow regime results in an increase in macrosegregation levels and a change in the pattern of solute redistribution. The most significant finding in the studies of 3XVAR processing of Ti-10-2-3 is the small effect of the electrode composition distribution on ingot segregation development. In both low and high power VAR cases, macrosegregation levels and patterns in the final ingots were similar to those demonstrated assuming a uniform electrode for that final case. However, for low power cases, nonuniformities in the electrode composition may strongly affect the final ingot macrosegregation. The nonuniformity in the composition of the electrode results in the formation of additional buoyancy forces within the liquid pool, which can cause a switch from buoyancy driven flow to the undesirable electromagnetically driven flow regime and a drastic change in segregation development.

Notes

Acknowledgments

This research was funded by the Specialty Metals Processing Consortium through Sandia National Labs (Albuquerque, NM) and the Purdue Research Foundation. The calculations were performed on a computational cluster donated by Intel Corporation.

References

  1. 1.
    L.A. Betram, R.S. Minisandram, K. Yu: in Modeling for Casting & Solidification Processing, Kuang-O Yu, ed., Marcel Dekker, New York, NY, 2002, pp. 565–611Google Scholar
  2. 2.
    W.D. Zeng, Y.G. Zhou: Mater. Sci. Eng. (A), 1999, vol. A260, pp. 203–11CrossRefGoogle Scholar
  3. 3.
    D. Zagrebelnyy: Ph.D. Dissertation, Purdue University, West Lafayette, IN, 2007Google Scholar
  4. 4.
    D. Zagrebelnyy, K. VanEvery, and M. John M. Krane: 2008, unpublished researchGoogle Scholar
  5. 5.
    W.D. Bennon, F.P. Incropera: Int. J. Heat Mass Transfer, 1987, vol. 30, pp. 2161–70MATHCrossRefGoogle Scholar
  6. 6.
    M.J.M Krane, F.P. Incropera, D.R. Gaskell: Int. J. Heat Mass Transfer, 1997, vol. 40, pp. 3827–35MATHCrossRefGoogle Scholar
  7. 7.
    K. VanEvery: Master’s Thesis, Purdue University, West Lafayette, IN, 2005Google Scholar
  8. 8.
    K. VanEvery, D. Zagrebelnyy, and M. John M. Krane: 2008, unpublished researchGoogle Scholar

Copyright information

© THE MINERALS, METALS & MATERIALS SOCIETY and ASM INTERNATIONAL 2008

Authors and Affiliations

  1. 1.School of Materials EngineeringPurdue UniversityWest LafayetteUSA
  2. 2.Republic Special MetalsCantonUSA

Personalised recommendations