ALLEVIATING DEFECTS IN CONTINUOUS-CAST INGOTS BY INSERTING VORTEX SUPPRESSORS IN THE TUNDISH

摘要

Automotive manufacturing is one of the main activities that uses cold-rolled sheet, and standards on the surface quality and strength of automobile sheet are continually being raised due to changes in the design of the body of the automobile, changes in the manufacturing technology, and the use of various types of coatings. However, it is impossible to completely eliminate random defects from the sheet. Study of defects in automobile sheet has shown that a significant percentage of them are related to the presence of slag inclusions - coarse, multiphase inclusions that consist of alumosilicates and spinels, silicate glasses, and corundum. Some of these inclusions are composed of emulsified slag from the tundish. Equipping tundishes with perforated full-profile partitions in tundishes in which the holes are oriented at a certain angle to the surface of the metal alleviates the contamination of the steel by these inclusions but does not completely solve the problem. It has been established that more slag is drawn down into the bottom part of the tundish when slab withdrawal speed is increased and when the stream of steel flowing from the pouring ladle into the tundish is asymmetric (the latter factor is related to the amount of slag that enters the bottom part of the tundish bottom due to the asymmetric distribution of dynamic pressure in front of the holes in the partitions).