Turbulent Flow and Particle Motion in Continuous Slab-Casting Molds

Turbulent flow in the continuous casting process involves transient phenomena and the transport of inclusion particles and plays an important role in the quality of the steel. As shown in Fig. 1, the molten steel jet entering the mold may carry inclusion particles (e.g. alumina) and argon bubbles. Liquid flux can also be entrained from the shear of the liquid flow across the top surface and form harmful inclusions. These inclusions and bubbles will either be safely transported to the top surface and removed by the slag layer, or become entrapped in the final product to form costly defects (e.g. internal porosity, blisters, slivers etc.). The flow in the mold region is highly turbulent with Reynolds numbers exceeding 100,000. The chaotic structures of this transient flow greatly influence the unsteady transport of the inclusions and bubbles, which has been evidenced by intermittent defects in plant observation . This transient flow itself is also of great interest for being associated with other defects. The time-varying top surface level, for instance, changes the thickness of the liquid flux layer covering the molten steel, and further affects the steady supply of liquid flux into the interfacial gap between the shell and mold. Sudden level fluctuations are associated with surface cracks and other defects in plant studies. The present study is part of a larger ongoing research project to investigate the transient structures of this mold flow and inclusion particle behavior with the objective of understanding and minimizing these defects.