PURPOSE: To produce low N-contg. steel of superior plastic workability by subjecting the molten steel of respectively specified contents of C, Si, Al and N to a cleaning and melting treatment and component control without Al deoxidation treatment, charging this steel together with a heat insulation type flux into a mold for casting and drawing it out continuously under electromagnetic induction agitation.
CONSTITUTION: The steel material contg. ≤0.25% C, ≤0.02% Si, ≤0.18% Al and ≤25ppm N is tapped into a ladle without undergoing a deoxidation treatment involving charging of Al at the tapping. The molten steel in the ladle is agitated by Ar to reduce inclusions and Al is charged thereto to control the Al component, after which the molten steel is supplied through an immersion nozzle into a mold for casting. While a heat insulation flux is charged onto the melt surface, the molten steel is drawn out continuously to the bottom of the mold and is solidified. It is necessary to draw out the molten steel from the mold while agitating the same by electromagnetic induction by the magnetic field induced by the AC of specified frequency and magnetic flux density in the mold.
KUCHIISHI SHIGEMATSU
SHIAKU KIYOSHI
KAWASAKI MASAZOU
EBATO KOUICHI
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