| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a method for refining molten steel in molten steel refining in which molten steel in a ladle is circulated to a reduced-pressure vacuum tank to be refined, reducible of A-type inclusions in a steel sheet while keeping an excellent rate of desulfurization, when desulfurizing refining is performed by adding a powder desulfurizing agent to the molten steel. <P>SOLUTION: In molten steel refining in which molten steel in a ladle is circulated to a reduced-pressure vacuum tank to be refined, desulfurizing refining is performed by adding a powder desulfurizing agent to the molten steel, then oxygen gas is sprayed to the molten steel in a vacuum tank to burn Al in the molten steel, and further, the molten steel is circulated between the ladle and the vacuum tank. Thereby, even when the powder desulfurizing agent with a small particle size is used as a desulfurizing agent, A-type inclusions are hardly generated in a hot-rolled steel sheet and ultra-low sulfur steel having favorable workability can be produced while resulfurization is suppressed. <P>COPYRIGHT: (C)2012,JPO&INPIT |
