9th ECCC European Continuous Casting Conference – ECCC 2017

This papers presents an experimental and numerical analysis of the redistribution of the alloy chemical components, the grain solidification structure and likelihood of porosity formation in continuous casting of stainless steel. An experimental setup consisting of a rectangular ingot was developed to mimic the solidification conditions of a continuous cast slab. The amount of energy extracted from the system was recorded and used as an input for the numerical model. Extensive experimental investigations were carried out to reveal the ingot cross sections grain structure features, including the CET location, and the three chemical component elements distribution. The experimental measurements of the secondary dendrite arms spacing were in agreement with the recorded cooling rate curves. A comprehensive modelling approach was adopted to take into account the effect of the solutal/thermal buoyancy forces driving the overall segregation at the casting scale. The model consists of two full coupled solvers which allow the simulation of grain structure at the full ingot scale. The energy, mass, flow and species balances equations are solved at the macro scale using Finite Volume (FV) method. In addition, the solidification grain structure is computed at the mesoscale; i.e. real time tracking of the growth of solidification grain structure is achieved and coupled with the FV solver resulting in the full ingot grain structure and grains boundaries and features (columnar/equiaxed). The mathematical model was implemented using openfoam, a C++ opensource library, and was validated against experimental and numerical benchmark. The solver, SPrime, was then used to predict the formation of macrosegregation and shrinkage cavity during the ingot solidification. The predicted as-cast structure and the columnar-to-equiaxed transition (CET) were in good agreement with the experimental data. The implantation of a dimensionless Niyama criterion which takes into account the alloy properties; offered better prediction of the porosity distribution.