A comparison of Fourier vs. Newtonian thermal analyse and its influence on the inverse kinetic growth calculation

• Thermal analysis of cooling curves is a metallurgical process control tool. Any phase transformations and their kinetics are reflected in the cooling rate. An interpretation of the cooling rate and temperatures is coupled to critical parameters, which are needed to assure correct quality of the melt and to give recommendations to modify the melt. This paper was inspired by the question, how well does a thermal ana lysis with one or two thermocouples and subsequent numerical analysis reflect the real phase transformations which occur?Inverse kinetic analysis using Fourier Thermal Analysis and Newtonian Thermal Analysis has been investigated using simulated cooling curves. The present study uses a direct simulation including a kinetic model for simulation of a eutectic phase. In this case, since the solidification sequence is well defined the inverse kinetic analysis should recreate the relation between the growth rate and supercooling of the eutectic phase. The Newtonian Thermal Analysis is based on an interpretation of a single thermal point with respect to solidification and contains a series of assumptions which are not entirely undoubted physically.Consequently the inverse kinetic analysis results in random quality growth parameters. The Fourier Thermal Analysis is based on interpretation of temperature differences between two thermal points with respect to solidification. The calculations conducted, in combination with the inverse kinetic analysis reveal a stable procedure. The decisive parameter determining the quality of inverse analysis is the distance between the thermal points analysed. Closely situated thermal points assure the best quality. The Fourier Thermal Analysis reflects the solidification most correctly.

Nyckelord

Inverse model

thermal analyze

fraction solid

kinetic model

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vet (ämneskategori)

ovr (ämneskategori)