Abstract
A physical model was established to study the mechanism of mould powder entrapment in the funnel type mould of a flexible thin slab casting machine, and the effects of operational parameters on the powder entrapment were investigated. The results show that there are three mechanisms of mould powder entrapment, vis-à-vis entrapment caused by shear stress, entrapment caused by vortex and entrapment caused by shear stress and vortex. Three different modes of the entrapment caused by the shear stress, between the mould powder and the molten steel flow produced by the flow from the upper ports of a four-port submerged entry nozzle, were observed. The entrapment caused by vortex occurs at the lowest position of the metal/slag interface. The entrapment caused by shear stress and vortex is a new mechanism, in which the powder is firstly drawn downward by shear stress and then pulls the powder layers above under the common action of shear stress and vortex.
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