METHOD FOR REFINING HIGH PURITY STEEL

摘要

PURPOSE: A method is provided to refine steel having less than 15ppm of the entire oxygen among high purity steel by taking caustic lime flux powder in a non-deoxidized molten steel and shape-controlling an inclusion with a calcium aluminate type inclusion. CONSTITUTION: Non-deoxidized molten steel refined in a converter is taken out by a ladle(10). Caustic lime flux powder(22) is taken to the molten steel(12) put in the ladle by transmission gas. An aluminium deoxidizing material is input in the molten steel in which the flux powder is put. Then, the molten steel is returned into a vacuum tub of RH. Herein, the particle degree of the caustic lime flux powder is less than 0.5mm and includes 68 to 87% of CaO and 10 to 30% of CaF2.