| 摘要 |
<p><P>PROBLEM TO BE SOLVED: To provide a smelting method for producing high-cleanliness steel containing extremely low sulfur [S] of 10 ppm or less and T. [O] of 40 ppm or less, without adding CaF<SB>2</SB>to the molten steel in a ladle and without raising a temperature of the molten steel tapped out from a converter, with a simple means. <P>SOLUTION: The smelting method for producing high-cleanliness steel containing extremely low sulfur [S] of 10 ppm or less and T. [O] of 40 ppm or less includes sequentially performing the steps of: (1) adding a CaO-based flux to the molten steel under ambient pressure; (2) agitating the molten steel and the CaO-based flux by blowing an agitation gas from a lance immersed in the molten steel in the ladle under ambient pressure, supplying an oxidizing gas to the molten steel, and mixing the oxide produced through a reaction between the oxidizing gas and the molten steel with the CaO-based flux; and (3) eliminating sulfide and inclusions in the molten steel by stopping the supply of the oxidizing gas and simultaneously blowing the agitation gas from the lance immersed in the molten steel in the ladle under ambient pressure. The method also includes controlling a ratio (t/t<SB>0</SB>) of an agitation period of time (t) in the step (3) to the oxidizing-gas-supplying period of time (t<SB>0</SB>) in the step (2) to 0.6 or more. <P>COPYRIGHT: (C)2007,JPO&INPIT</p> |
