Free-surface flow and vortex formation in the continuous cast molding
Overview: Continuous casting is used to manufacture more than 90% of steel in the world, so understanding and optimizing the process is important to minimize defects in steel, most of which being associated with surface flow structure in the mold. Asymmetric surface flow in the mold is one of the main phenomena attributed to cause inclusion entrainment, which can make “sliver” defects in the rolled product, caused by inclusions being trapped in the solidifying shell in the mold.
The challenge: The nozzle flow pattern can be altered by various unexpected elements, such as slight deposition of impurities forming clogged regions, resulting in asymmetric flow in the mold. This in turn may lead to rapid interface deformations on one side of the mold, causing free-surface level fluctuations, vortices and instability of the interfacial layer between the molten steel and liquid mold flux. These phenomena can entrain liquid mold flux into the molten steel, inducing entrapment of inclusions into the solidifying steel shell.
TransAT Solution: Use of a subtle model combination in TransAT consisting of the level-set model for surface deformations and LES for turbulence (LEIS) turned out to be the right way to tackle this problem. In particular, the model predicts surface fluctuations and interactions with turbulence, surface vortexting as shown in the 2nd panel, and the currents induced in the liquid bath and the consequent mixing. The model has recently been completed by heat transfer and phase change capabilities, which could deal with real casting problems.
InfoExpert: Contact our expert
Jan van Rickenbach
Tel. + 41-44-445-4073