| 摘要 |
<p>PROBLEM TO BE SOLVED: To perform the heat-up without damaging the cleanliness in molten steel and also, without increasing carbon content even in the case of restraining the carbon concentration to low, such as an extra-low carbon steel, when the molten steel during treating in a vacuum refining furnace, is heated up by burning Al with oxygen. SOLUTION: Into the molten steel 3 refined in the vacuum refining furnace 1, the metallic Al or flux containing the metallic Al together with the oxygen or the oxygen-contained gas, are blown upon or blown into the molten steel. At this time, from a viewpoint of the secureness to the cleanliness in the molten steel, it is desirable that the flux containing CaO is used as the flux containing the metallic Al, the flux containing CaO is added into the molten steel at the same time of blowing the metallic Al or the flux containing the metallic Al upon or into the molten steel, and further, the adding quantity of CaO to the adding quantity of the metallic Al is regulated to in the range of 0.9-5.0 as the mass ratio.</p> |
