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Modelling Decarburization in Electrical Steels
Author(s) -
Soenen Bart,
Jacobs Sigrid,
Wulf Marc De
Publication year - 2005
Publication title -
steel research international
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.603
H-Index - 49
eISSN - 1869-344X
pISSN - 1611-3683
DOI - 10.1002/srin.200506032
Subject(s) - decarburization , annealing (glass) , materials science , metallurgy , diffusion , thermodynamics , physics
A model is presented to predict the decarburization rate of electrical steels during reactive annealing. In a first step, the warm annealing atmosphere composition is calculated as function of the composition of the cold gas containing N 2 ‐H 2 ‐H 2 O‐CO‐CO 2 ‐CH 4 ‐O 2 . In a second step, the decarburization kinetics, which is controlled both by the surface reaction and by the diffusion of carbon towards the surface, is calculated. The model is then used to study the balance between surface reaction and the diffusion control of the decarburization process. We could conclude that for low sheet thickness and/or low H 2 O/H 2 ratio in the annealing atmosphere, the decarburization is surface reaction controlled, while for commercial thicknesses and industrially applied dew points, the process is diffusion controlled. Furthermore, we looked at the difference in decarburization between complex N 2 ‐H 2 ‐H 2 O‐CO‐CO 2 atmospheres used in industrial application, and N 2 ‐H 2 ‐H 2 O atmospheres typically used in lab annealing. We could conclude that the decarburization rate is influenced by the addition of CO and CO 2 and that the final carbon level is increased if CO and CO 2 are added to the gas.