PREVENTING METHOD FOR PICKUP OF NITROGEN IN ARC PROCESS

摘要

PURPOSE:To decrease the amt. of an inert gas to be used by forming a gas flow path to an electrode to be immersed in slag and discharging the inert gas to increase the slag thickness and to decrease the amt. of the inert gas to be supplied. CONSTITUTION:A molten steel 3 is tapped from a converter into a ladle 1 and the electrode 5 is immersed in the slag 4 on the molten steel 3. The electrode 5 is then energized to form an arc between the electrode 5 and the molten steel 3 and to heat the molten steel 3 by the arc. The inert gas (gaseous Ar) is discharged as a prescribed flow rate from the gas flow path 6 provided to the electrode 5 in the longitudinal direction thereof to fill the circumference of the arc with the inert gas and to prevent the nitrogen pickup of the molten steel 3. A flux is introduced into the molten steel 3 to execute the slag refining of the molten steel 3 with progression of the arc heating treatment and therefore the thickness of the slag 4 increases gradually. The flow rate of the inert gas to be discharged is so adjusted as to be decreased with an increase in the slag 4.