Melt flow and cleanliness in continuous casting tundishes.

摘要

The most efficient and widely adopted method for producing high quality steel is the continuous casting process where the tundish plays an important role. Melt flow in the tundish controls, to a large extent, the cleanliness and quality of the cast product. Thus, fluid flow in tundishes was studied for several different situations.;Flow of fluid in inclined wall tundishes was obtained numerically by developing three dimensional finite difference mathematical models of flow. The predicted results gave good comparison to results obtained from water model experiments.;Water modeling experiments were performed to find out optimum flow configurations in terms of inclusion removal when different flow control devices such as dam, weir and baffle with holes are used. The best configuration were obtained when a dam, weir and baffle combination was used.;During the grade change operations in continuous casting, a new composition of steel is poured into a tundish containing steel of different composition. Consequently, a lot of undesirable "mixed" tonnage of steel is generated. A novel technique has been developed, which has been shown to minimize this mixed volume by about 70%, with the use of a moving baffle.;The fluid flow pattern in shallow strip casting tundishes greatly influences the uniformity of thickness of the strip produced. Both physical and mathematical modeling were performed to study the detailed flow structure and turbulence present in such tundishes.;A mathematical model was developed to simulate the phenomena of transport and removal of inclusions from the tundish. A comparative study of three different flow configurations was performed using this model. The study indicated that the mechanism of inclusion removal by sticking to solid surfaces contributed greatly to the total inclusion removal rate. Inclusion collision to form bigger sized inclusions occurred in regions of high turbulence such as near the inlet flow region. Bigger sized inclusions were removed from the tundish primarily by floating out to the top surface. The flow configuration using dam, weir and baffle with holes resulted in the maximum inclusion removal rate compared to the other two configurations.