9th ECCC European Continuous Casting Conference – ECCC 2017

It is well known now that the cast product defects like hot tears or cracks are rooted at the first beginning of the solid shell birth. Damages result from the competition between hydrostatic pressure within the turbulent flow exit from the SEN and the solidifying skin under tensile stresses and strains state. In addition, the thermal energy extracted from the cast product by the mold has huge impact of the thickness of the shell. It depends on the air gap growth issued from the shrinkage of the solidifying metal together with the deformation of the mold components. In addition, slag that can be inserted between mold and product shell is also impacting the heat exchanges. Numerically speaking, the method able at taking all that phenomena into account through an accurate way is a multi-physics fluid/structure model. Indeed, a standard CFD method does not represent the solid behavior, so that the stresses, strains, air gap evolution due to the shrinkage of the shell are not reachable. In this paper, a new 3D fluid/structure model involving the turbulent fluid flow and the solid constitutive equation is described. The management of the dedicated “liquid time step” allowing high velocity motion into the liquid phase of the alloy coupled with the “solid time step” dealing with the solid phase and the corresponding slow motion, is presented. The model considers as well added slag floating at cast product surface impacting not only the heat exchanges with ambient but also with mold during casting process. An application on continuous casting process taking into account the coupling with the heat control of the mold is presented. Finally, it is shown that the global behavior of the complex system is converging till a quasi steady state, so that it is really possible to optimize the casting process.