A model for the calculation of flow patterns and inclusion separation in continuous casting tundishes is described. Velocity and turbulence fields for the liquid steel are calculated, assuming three-dimensional, turbulent steady-state flow. A transport equation for particles is solved, which takes into account buoyancy, convection und turbulent dispersion. Particle concentration fields and the percentage of removed particles are calculated as a function of particle rise velocity. The influence of increased tundish width and height and of dams and weirs on the rate of inclusion separation is investigated for a slab caster tundish. Non-dimensional representations and approximation expressions are discussed and used to compare the computed removal rates to measured values from literature. Stahlstromunq und EinschluBabscheidung in GieBverteilern von StranggieBanlagen. Ein Modell zur Berechnung von Stromungsprofilen und EinschluBabscheidung in Verteilerqefalsen von StranggieBanlagen wird beschrieben. Geschwindigkeitsund Turbulenzfelder fur flussiqen Stahl werden unter Annahme eines dreidimensionalen, turbulent stationaren Strornunqszustandes berechnet. Unter Berucksichtiqunq von Antrieb, Konvektion und turbulenter Dispersion wird eine Transportgleichung fur Teilchen erstellt. Konzentrationsfelder der Teilchen und der Prozentsatz der abgeschiedenen Teilchen werden als Funktion der Teilchen-Aufstiegsgeschwindigkeit berechnet. Der EinfluB einer Verqrolserunq des Verteilerqefafses in Breite und Hohe sowie von Dammen und Wehren auf die Abscheidungsrate von Einschliissen wird fur ein VerteilergefaB einer Brammenstrang-gieBanlage ermittelt. Dimensionslose Darstellungen und Naherunqsforrneln werden diskutiert und zum Vergleich von berechneten Abscheidungsraten mit MeBwerten aus der Literatur verwendet.

SUMMARYA mathematical model has been developed to quantify the effects of process conditions during turbulent solidification and mixing of a liquid metal jet in a confined co-flowing molten metal stream.The modelling has been split into three parts. First, a single phase model with no latent heat effects to consider the solidification potential. Secondly, a two phase model where the second phase is comprised of solid particles which solidify during mixing of the two streams. Thirdly, a two phase model where the second phase consists of the inner jet, which is assumed to break up into droplets of given size, and solid particles are allowed to form by solidification within the droplets.The results show that the thermal history (solidification path) of the solid phase formed is affected by latent heat and particle sLe, which implies that solidification, nucleation and jet fragmentation events should be included dynamically to ensure realistic predictions. METALLURGICAL BACKGROUNDThe mechanical properties of metal alloys are controlled by their microstructure, which in turn is largely controlled by the solidification mode during casting. For a number of applications it is desirable to make the structure as fine and uniform as possiblc, and this can be achieved by solidifying the melt very rapidly.There are a variety of methods commonly used for achieving rapid solidification which involve fragmentation of a melt into droplets (e.g. atomization) or stabilkation of thin melt sections to produce ribbons or flakes (e.g. melt spinning),' but for most applications the resultant materials must be reconsolidated into a bulk product via elaborate and often costly fabrication routes. Moreover, the extensive thermomcchanical treatments involved in reconsolidating often result in a loss of mechanical properties in the finished product, due to the accelerated kinetics of solid state transformations. The 1 urbulent solidification process described here has bcen developed by Alcan International to help overcome the abovc kinetic constraints as well as avoiding the need to reconsolidate.The process is best described by reference to Figure 1. The final alloy composition is initially split inlo two components; a minor component ofhigh concentration and high melling point (feedstock)

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