| 摘要 |
PROBLEM TO BE SOLVED: To obtain powder for continuously casting a steel having difficult-to- entrapping and excellent lubricity without developing powdering defect by using the powder having a specific value or higher of the viscosity at a specific temp. when the shearing speed is a specific value or lower, and a specific value or lower of the viscosity at the specific temp. when the shearing speed is a specific value or higher. SOLUTION: It is desirable to use the powder having >=5 poise of the viscosity at 1300 deg.C when the shearing speed is <=20 (l/sec) and <=4 poise of the viscosity at 1300 deg.C when the shearing speed is >=80 (l/sec). At a portion A of molten steel 3, the shearing speed is 80-160 (l/sec) with the oscillation of a mold 1 and at a portion B, the shearing speed is 10-40 (l/sec) with the molten steel fluid. The molten layer 5 of the powder is low viscosity and high lubricity at the portion A and is high viscosity and difficult-to-entrap at the portion B. The composition of the powder is e.g. by wt.% of 30; CaO 30; SiO2, 20; Al2O3, 10; F, 5; N and 5; Li2O.
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