Improvement of Macrosegregation in Continuously Cast Bloom and Billet by Electromagnetic Stirring

Abstract

Center segregation is one of the most harmful defects especially for the production of high carbon steel by the continuous casting process.
Many experiments were performed to improve center segregation through laboratory tests and plant trials. In the plant trials of bloom c.c. and billet c.c., two or three stirrers were installed at a mold, the upper and lower parts of the secondary cooling zone.
As a result, it was found that both the deviation and the mean value of center segregation were gteatly reduced by combination stirring at the mold and in the lower part of the secondary cooling zone. Furthermore, there was an optimum condition for the stirring at a later stage of solidification and center segregation showed no change or even became worse if the stirring condition was not satisfactory.
Combination stirring was adopted to the bloom caster and as a result, high quality steels for rods and bars are being produced.