Casting/mold thermal contact heat transfer during solidification of Al-Cu-Si alloy (LM 21) plates in thick and thin molds |
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Authors: | K Narayan Prabhu Bheemappa Chowdary N Venkataraman |
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Affiliation: | (1) Department of Metallurgical & Materials Engineering, National Institute of Technology Karnataka, P.O. Srinivasnagar, 575 025 Surathkal, India;(2) NITK, Surathkal;(3) Present address: M/s Chowgule Industries Limited, Panaji, Goa, India;(4) National Institute of Technology Karnataka, Surathkal, India |
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Abstract: | Heat flow at the casting/mold interface was assessed and studied during solidification of Al-Cu-Si (LM 21) alloy in preheated
cast iron molds of two different thicknesses, coated with graphite and alumina based dressings. The casting and the mold were
instrumented with thermocouples connected to a computer controlled temperature data acquisition system. The thermal history
at nodal locations in the mold and casting obtained during experimentation was used to estimate the heat flux by solving the
one-dimensional inverse heat conduction problem. The cooling rate and solidification time were measured using the computer-aided
cooling curve analysis data. The estimated heat flux transients showed a peak due to the formation of a stable solid shell,
which has a higher thermal conductivity compared with the liquid metal in contact with the mold wall prior to the occurrence
of the peak. The high values of heat flux transients obtained with thin molds were attributed to mold distortion due to thermal
stresses. For thin molds, assumption of Newtonian heating yielded reliable interfacial heat transfer coefficients as compared
with one-dimensional inverse modeling. The time of occurrence of peak heat flux increased with a decrease in the mold wall
thickness and increase in the casting thickness. |
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Keywords: | casting/mold interface heat conduction inverse modeling Newtonian heating solidification |
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