Abstract
Solidification of metal castings inside moulds is mainly dependent on the heat flow from the metal to the mould which is in turn proportional to an overall heat transfer coefficient h which includes all resistances to heat flow such as the presence of an air gap. In the present work the heat transfer coefficient is determined using a directional solidification set-up with end chill for solidifying commercial-purity aluminium with different superheats (40 K and 115 K) against copper chill. A computer program solving the heat conduction and convection in the solidifying metal is used together with the experimental temperature history in order to determine the heat transfer coefficient at the interface. The variation of h as a function of time, surface temperature and gap temperature for each melt superheat is found. The results indicate that h reaches a maximum value for surface temperature close to the liquidus. The analysis of heat flux from the metal to the mould indicates that it is mainly by conduction. The air gap size is evaluated with time, surface temperature and with melt superheat. It is found that higher h values and smaller gap sizes are obtained with higher superheats.
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References
P. R. Sahm and P. N. Hansen, “Numerical simulation and modelling of casting and solidification processes for foundry and cast-house” (Comité International des Associations Techniques de Forderiet (CIATF), Switzerland, 1984).
S. R. Robertson and E. F. Fascetta, Met. Trans. 8B (1977) 619.
A. Garcia, T. W. Clyne and M. Prates, ibid. 10B (1979) 82.
H. Jacobi, Arch. Eisenhuttenwesen, 47 (1976) 441.
M. Prates and H. Biloni, Met. Trans. 3 (1972) 1501.
S. A. Levy, S. Lipson and H. Rosenthal, AFS Cast Metals Research J. 5 (1969) 9.
E. S. Tillman and J. T. Berry, ibid. 8 (1972) 1.
K. Ho and R. D. Pehlke, AFS Trans. 91 (1983) 689.
Idem., Met. Trans. 16B (1985) 585.
Y. Nishida, W. Droste and S. Engler, ibid. 17B (1986) 833.
N. A. El-Mahallawy and A. M. Assar, J. Mater. Sci. Lett. 7 (1988) 205.
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El-Mahallawy, N.A., Assar, A.M. Effect of melt superheat on heat transfer coefficient for aluminium solidifying against copper chill. J Mater Sci 26, 1729–1733 (1991). https://doi.org/10.1007/BF00543594
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DOI: https://doi.org/10.1007/BF00543594