ISIJ International
Online ISSN : 1347-5460
Print ISSN : 0915-1559
ISSN-L : 0915-1559
Regular Article
Evaluation of Defect Distribution in Continuously-Cast Slabs by Using Ultrasonic Defect Detection System and Effect of Electromagnetic Brake on Decreasing Unbalanced Flow in Mold
Kohei Furumai Yutaka MatsuiTakeshi MuraiYuji Miki
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2015 Volume 55 Issue 10 Pages 2135-2141


In order to clarify the suppression mechanism of an unbalanced flow in the continuous casting mold under high molten steel throughput conditions, the relationship between the unbalanced flow and the distribution of defects entrapped on the solidified shell was measured by ultrasonic defect detection. The relationship between the unbalanced flow and the defect distribution in the mold with an electromagnetic brake was also investigated. The main results are summarized as follows.
(1) By using a new ultrasonic defect detection system, accurate measurement of defects was achieved for the defects’ diameter of more than 0.6 mm in the range 2–10 mm from surface.
(2) The effect of the electromagnetic brake on decreasing molten steel momentum was measured. The measured value was consistent with the calculated value. Molten steel momentum could be reduced by more than 50% when the Stuart number (N) was more than 3.5 under molten steel throughput conditions of 4.7 and 5.3 ton/min.
(3) The position of entrapped defects on the solidified shell in the mold was influenced by the molten steel throughput condition and the magnetic flux density of the electromagnetic brake.

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© 2015 by The Iron and Steel Institute of Japan
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