| 摘要 |
PROBLEM TO BE SOLVED: To obtain a continuous casting method of a steel, in which the cooling can be executed so as to lower the temp. on the surface of a steel slab once lower than the A3 transformation temp. or so as not to lower the temp. thereon lower than the A3 transformation temp., by using the same air-water nozzle, when secondary cooling of the cast slab is performed with the air-water mist. SOLUTION: The length from the mixing part of the water and the air in the nozzle to the tip part of the nozzle is 100-300 mm, and in between the straightening position of the cast slab, in the case of reheating it to the A3 transformation temp. or higher after lowering the temp. of the cast slab surface once lower than the A3 transformation temp., the mixing ratio A/W (vol. ratio) of the air A and the water W at a room temp. and ordinary pressure, is regulated to 5-15, and the water quantity density is regulated to 0.03-0.09 l/cm2.min. In the case the temp. of the cast slab surface is not lowered than the A3 transformation temp., the mixing ratio A/W (vol. ratio) of the A and the water W at a room temp. and ordinary pressure, is regulated to 50-200 and the water quantity density is regulated to 0.005-0.015 l/cm2.min.
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