An investigation of slag floatation and entrapment in a continuous-casting tundish using fluid-flow simulations, sampling and physical metallurgy

Some aspects of inclusion behaviour in the tundish have been investigated both theoretically and experimentally. Good agreement was obtained between measured and predicted temperature and flow fields for 1- to 6-strand continuous-casting tundishes. In this study the flow field was redesigned with weirs, resulting in the addition of a vertical component to Stoke's equation. The results indicate an increase in the velocity that cause a rise of inclusions (smaller inclusions (<20 mum)). Consideration of slag, flux and refractory in the model has also made it possible to simulate the mixing of steel and slag. Special sampling techniques were used to gather information. Samples were analysed using ultrasonic testing, LOM, SEM and Atomic Force Microscopy (AFM). The analysis results were used to verify the predictions regarding steel/slag mixing and understanding of physical conditions at the interfaces. As a result, the casting praxis was improved (cleaner steel) and the products were of higher quality.