9th ECCC European Continuous Casting Conference – ECCC 2017

Hot tearing is a regular defect that affects slab internal soundness. Hot tears form at the end of solidification, typically between 0.8 and 1 solid fraction, when steel exhibits low ductility but can be subjected to stresses which generate deformation. Excessive deformation will then open the dendritic structure and lead to cracks. New steel grades which are currently under development are sensitive to hot tears. Predicting hot tear is thus of primary interest for steelmaker in order to identify key process parameters which lead to hot tears and study level of these parameters. The aim of this study is to evaluate hot tears risks through thermomechanical simulations coupled with computation of an internal crack criterion. Simulations are done with Thercast® software [1] and the internal crack criterion used is a mechanical based criterion (Won criterion [2]). It predicts internal cracks if the cumulated tension strain is higher a critical strain. A good agreement is obtained between the thermomechanical simulation predictions and the experimental results for two configurations: classical bending test and semi-industrial continuous casting pilot trial with reheating to promote internal cracks. [1] O. Jaouen, F. Costes and P. Lasne, "Finite element thermo-mechanical simulation of steel making from solidification to the first forming operation", Metec InSteelCon, Düsseldorf (2011). [2] YM. Won, TJ. Yeo, DJ. Deol, KH. Oh, "A new criterion for internal crack formation in continuously cast steels", Metallurgical and Materials Transactions B, Volume 31B, 2000, p779-794.