Thermo-mechanical behavior of steel in the continuous casting process from meniscus to caster exit
An efficient computational model has been developed to quantify the thermo-mechanical behavior of the solidifying strand widefaces from meniscus to caster exit. A constitutive model is also developed for steel multiphase mixtures near the eutectoid transformation. This new constitutive model extends the temperature range of existing constitutive models for steel below the temperature range for the austenite phase. The domain of the solidifying steel strand model is a one-dimensional drilling through the strand widefaces, from the inner to the outer radius surface. The model considers the effects of mold cooling, secondary cooling, bending and unbending on the mechanical loading history of the strand. The thermal behavior of the model is calculated using boundary conditions from CON1D, in the mold and in secondary cooling. The thermal boundary conditions in secondary cooling consider the heat extraction of roll contacts and water sprays individually. Specialized boundary conditions are used to simulate bending and unbending and the hard box bending assumption is used. Good agreement is found between the model predicted surface strains during bending and unbending and a simple equation. It was found that non-uniform heat extraction at the strand surface during secondary cooling causes surface temperature fluctuations up to 200°C. These surface temperature fluctuations create cyclic mechanical loading at the strand surface, increasing the risk of transverse crack formation. Reduction in the severity of the surface temperature fluctuations should reduce the severity of the cyclic mechanical loading, and decrease the risk of transverse crack formation.
continuous casting, bending: unbending, straightening, secondary cooling, transverse cracks, steel, constitutive model, mixture model, phase fraction
University of Illinois - Urbana-Champaign
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University of Illinois at Urbana-Champaign