Improvement of Center Segregation in A New Large 400X500 MM2 Bloom Caster with EMS and Soft Reduction

by Kyung Shik Oh, Joo Dong Lee

Publisher - POSCO, Korea

Category - General Novel

A new large bloom caster of 400x500mm section size was built and started up at Feb. 29, 2008 to satisfy requirement of high quality for the high grade steels such as tire cord steel, bearing steel, spring steel, and cold heading quality(CHQ) steel for automobiles. Surface and internal quality of the wire rods produced from the large sized bloom was found to be better than the existing bloom of 300x400mm section size. Mold EMS enlarged equiaxed zone to 55% and final EMS and soft reduction reduced center segregation level of the bloom for tire cord steel from 3.35 to 1.75. The effect of soft reduction on center segregation of blooms was the largest among various casting parameters. For optimum use of soft reduction, precise roll gap calibration, correct reduction zone and thickness, proper combination of roll pressure, reduction thickness and ordered thickness should be satisfied. Since start up of the new bloom caster, annual sales amount of the high grade steels was increased from 710,000 ton to 840,000 ton.

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