Speaker
Description
A simple Lagrangean traveling slice model has been successfully used in the past for prediction of the relations between the process parameters and the temperature field in steel continuous casters. Such models are used in basic process parameters optimization with respect to the casting format and steel-grade. It is the purpose of the present paper to include also the concentration, mechanical stress and deformation models as well as the grain structure model on top of the temperature model. The basis of all the mentioned additional models is the slice heat-conduction model that takes into account the complex heat extraction mechanisms in the mould, with the sprays, rolls and through the radiation. Its main advantage is very fast calculation time and disadvantage that there is no other interaction but the convection in the direction of the casting. The macroscopic model used in this study is based on the continuum mixture theory, calculating enthalpy and mixture composition as input parameters for microscopic calculations. The grain structure model is based on the cellular automata concept, replaced by a random node point automata concept. The macrosegregation model is based on the Scheil rule microsegregation model. The thermal conductivity and the species diffusivity of the liquid phase are artificially enhanced to consider the convection of the melt. The calculated thermal field is used to estimate the thermal contraction of the solid shell, which, in combination with the metallostatic pressure, drives the elastic-viscoplastic model. The results of the model are used to estimate the areas susceptible to crack nucleation using several hot-tearing and damage models. A sensitivity study on the recently introduced standard continuous casting test geometry is performed as well as on the realistic conditions in a round and square billet caster. Possible additional refinements of the model are discussed.