| 摘要 |
PROBLEM TO BE SOLVED: To provide a method for continuously casting steel with which a cast slab excellent in the cleanliness can stably be produced at low production cost. SOLUTION: This casting method is applied under a condition of >=1.5τp, whereinτp is an oxide float-up index in molten steel defined by the following equation (A) obtained by dividing tS (s) being the staying time defined by the following equation (B) by tV (s) being the time defined with the following equation (C) and needed for an oxide having 100μm diameter existing in the molten steel near the bottom surface of a tundish to float up to the surface of the molten steel. The equations are:τp=tS/tV...(A), ts=W1/W2...(B), and tV =18×μS×h/ (ρS-ρI)×α×DI2}...(C), wherein W1 is the molten steel quantity in the tundish, W2 is the discharge quantity from the tundish,μS is the viscosity of the molten steel, h is the molten steel depth in the tundish,ρS is the density of the molten steelρI is the density of the oxide in the molten steel,αis the gravitational acceleration, DI is the diameter of the oxide in the molten steel.
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