QUANTITATIVE-ANALYSIS OF CONTAMINATION OF LIQUID STEEL IN TUNDISH

Recently, the high grade quality has been demanded for strips and surf ace-treatment steel plates. Especially, the cleanliness of molten stee l in tundishs plays a crucial part in order to improve the quality of steel plate as well as to prevent immersion nozzle clogging. The tundi sh has functions of floatation and removal of inclusions, though, some contaminations to the molten steel also occur in tundishs. Therefore, it is necessary to make clear the cause of each contamination and the ir level for producing super clean steels. In this study, the contamin ation factors to molten steel in the tundish and their influences were analyzed by continual metal sampling during operation and of investig ation of size, number and composition of inclusions. The results are a s follows. (1) Air-oxidation to molten steel is the biggest factor of contamination in the tundish. (2)As the influence of air-oxidation dec reases, slag contamination increases during continuous operations.