Modeling of macrosegregation due to thermosolutal convection and contraction-driven flow in direct chill continuous casting of an Al-Cu round ingot
Tóm tắt
Macrosegregation in direct chill (DC) continuous casting of an Al-4.5 wt pct Cu round ingot is numerically simulated. The model incorporates descriptions of heat transfer, solute redistribution, and melt convection on the system scale with microscopic relations for grain growth, solutal undercooling, and microsegregation. Simulations are conducted to study the effects of mushy zone permeability, thermosolutal convection, and solidification contraction on the macrosegregation pattern in a DC casting. The results indicate that centerline segregation can be either positive or negative, depending upon the grain density in and permeability of the mush. In addition, it is shown that the flow induced by solidification contraction not only causes inverse segregation at the ingot surface, but also has a significant influence on the macrosegregation across the central portion of the ingot. A comparison with temperature and macrosegregation patterns measured in a previous experiment shows reasonable agreement. Several areas for future model improvements are identified.
Tài liệu tham khảo
M.G. Chu and J.E. Jacoby: Light Met., 1990, pp. 925–30.
H. Yu and D.A. Granger: Aluminum Alloys: Their Physical and Mechanical Properties, Proc. Int. Conf., Charlottesville, VA, EMAS, United Kingdom, 1986, vol. 1, pp. 17–29.
H. Kastner: Z. Metallk., 1950, vol. 41, pp. 193–205 and 247–54.
K. Buxmann: Metallurgy, 1977, vol. 31, pp. 163–70.
R. Ellerbrok and S. Engler: Metallurgy, 1983, vol. 37, pp. 784–88.
L. Ohm and S. Engler: Metallurgy, 1989, vol. 43, pp. 520–24.
M.C. Flemings and G.E. Nereo: Trans. TMS-AIME, 1967, vol. 239, pp. 1449–61.
M.C. Flemings, R. Mehrabian, and G.E. Nereo: Trans. TMS-AIME, 1968, vol. 242, pp. 41–49.
R. Mehrabian, M. Keane, and M.C. Flemings: Metall. Trans., 1970, vol. 1, pp. 1210–20.
T.L. Finn, M.G. Chu, and W.D. Bennon: in Micro/Macro Scale Phenomena in Solidification, C. Beckermann, L.A. Bertram, S.J. Pien, and R.E. Smelser, eds., ASME, New York, NY, 1992, HTD-vol. 218/AMD-vol. 139, pp. 17–26.
B. Gariepy and Y. Caron: Light Met., 1991, pp. 961–71.
S.C. Flood, L. Katgerman, A.H. Langille, S. Rogers, and C.M. Read: Light Met., 1988, pp. 943–47.
S.C. Flood, L. Katgerman, and V.R. Voller: in Modeling of Casting, Welding and Advanced Solidification Processes V, M. Rappaz, M.R. Ozgu, and K.W. Mahin, eds., TMS, Warrendale, PA, 1991, pp. 683–90.
B.Q. Li, J.C. Liu, and J.A. Brock: in EDP Congr., TMS, Warrendale, PA, 1992, pp. 841–57.
B.Q. Li and P.N. Anyalebechi: in Transport Phenomena in Solidification, C. Beckermann, H.P. Wang, L.A. Bertram, M.S. Sohal, and S.I. Guceri, eds., ASME, New York, NY, 1994, HTD-vol. 284, AMD-vol. 182, pp. 97–107.
Ch. Raffourt, Y. Fautrelle, J.L. Meyer, and B. Hannart: in Modeling of Casting, Welding and Advanced Solidification Processes V, M. Rappaz, M.R. Ozgu, and K.W. Mahin, eds., TMS, Warrendale, PA, 1991, pp. 691–98.
C. Devadas and J.F. Grandfield: Light Met., 1991, pp. 883–92.
G.U. Grün, I. Eick, and D. Vogelsang: Light Met., 1994, pp. 863–69.
A.V. Reddy and C. Beckermann: in Materials Processing in the Computer Age II, V.R. Voller, S.P. Marsh, and N. El-Kaddah, eds., TMS, Warrendale, PA, 1994, pp. 89–102.
A. Hakonsen and D. Mortensen: in Modeling of Casting, Welding and Advanced Solidification Processes VII, M. Cross and J. Campbell, eds., TMS, Warrendale, PA, 1995, pp. 763–70.
J. Ni and C. Beckermann: Metall. Trans. B, 1991, vol. 22B, pp. 349–61.
C. Beckermann and C.Y. Wang: in Annual Review of Heat Transfer VI, C.L. Tien, ed., Begell House, New York, NY, 1995, pp. 115–98.
P.J. Prescott and F.P. Incropera: in Advances in Heat Transfer, D. Poulikakos, ed., Academic Press, New York, NY, 1996, vol. 28, pp. 231–338.
S.C. Flood, P.A. Davidson, and S. Rogers: in Modeling of Casting, Welding and Advanced Solidification Processes VII, M. Cross and J. Campbell, eds., TMS, Warrendale, PA, 1995, pp. 801–08.
E. Haug, A. Mo, and H.J. Thevik: Int. J. Heat Mass Transfer, 1995, vol. 38, pp. 1553–63.
J. Ni and C. Beckermann: J. Mater. Processing Manufacturing Sci., 1993, vol. 2, pp. 217–31.
P.K. Agarwal and B.K. O’Neill: Chem. Eng. Sci., 1988, vol. 43 (9), pp. 2487–99.
P.N. Rowe and K.T. Claxton: Trans. Inst. Chem. Eng., 1965, vol. 43, pp. T321-T331.
S. Ganesan and D.R. Poirier: Metall. Trans. A, 1987, vol. 18A, pp. 721–23.
C.Y. Wang and C. Beckermann: in Materials Processing in the Computer Age II, V.R. Voller, S.P. Marsh, and N. El-Kaddah, eds., TMS, Warrendale, PA, 1994, pp. 129–43.
C.Y. Wang and C. Beckermann: Mater. Sci. Eng. A, 1993, vol. A171, pp. 199–211.
A.V. Reddy: Ph.D. Thesis, University of Iowa, Iowa City, IA, 1995.
D.P. Ziegler: Alcoa Technical Center, Alcoa Center, PA, private communication, 1994.
M. Rappaz, J.L. Desbiolles, J.M. Drezet, Ch.A. Gandin, A. Jacot, and Ph. Thevoz: in Modeling of Casting, Welding and Advanced Solidification Processes VII, M. Cross and J. Campbell, eds., TMS, Warrendale, PA, 1995, pp. 449–57.
D.C. Weckman and P. Niessen: Metall. Trans. B, 1992, vol. 23B, pp. 593–602.
R.T. DeHoff and F.N. Rhines: Quantitative Microscopy, McGraw-Hill Book Company, New York, NY, 1968.
P. Rousset, M. Rappaz, and B. Hannart: Metall. Trans. A, 1995, vol. 26A, pp. 2349–58.