| 摘要 |
PURPOSE:To perform refining by vacuum-degassing with high oxygen efficiency with decreased sticking of a base metal by positioning the tip of an oxygen blowing nozzle in the range between the high level of the molten steel in the stage of refining the molten steel which is not yet deoxidized and the low level of the molten steel in the stage of refining the molten steel which is oxidized. CONSTITUTION:An oxygen blowing nozzle 6 is provided by positioning the tip thereof to the position lower than the high level of the molten steel during the reaction in the stage of reflux refining of the molten steel which is not yet deoxidized and is to be subjected to decarburizing, etc. and in the position higher than the low level of the molten steel in the stage of reflux refining of the molten steel which is oxidized in an upper vessel 1 of a vacuum degassing and refining device. The nozzle 6 is attached preferably at 20-50 deg. angle. Since oxygen is directly blown to the molten steel by such device, approximately 95-100% oxygen efficiency is assured. Since the degree of vacuum is low, the volumetric expansion of the gas is small and the splashing of the molten steel 5 is suppressed. |
