VACUUM-REFINING METHOD OF MOLTEN STEEL HAVING HIGH DECARBURIZING CHARACTERISTIC

摘要

PURPOSE: To provide an effective refining method by which decarburizing velocity is not lowered even in the case of an extradecarburizing treatment in a vacuum-refining furnace. ;CONSTITUTION: In this vacuum-refining method of the molten steel 4, a straight barrel-shaped immersion vessel 1 is dipped into the molten steel 4 in a ladle tapped from a refining furnace, and also, the pressure in the immersion vessel 1 is reduced and gas for stirring is supplied from a lower position than the lower end of the immersion vessel. In the case of reducing the pressure to 50Torr in the immersion vessel, the horizontal surface corresponding to the geometrically generated molten steel surface level in the immersion tube is used as the reference and the diameter A of the immersion vessel at the upper side from this horizontal surface is enlarged from 1.1×D to 2.4×D of the diameter D of the immersion vessel at the lower part than the horizontal surface. By this method, the wide bubble activating surface is obtd. without lowering the molten steel surface level and, even in the case of the extra-low carbon range, the vacuum-refining is executed to the molten steel having high decarburizing characteristic.;COPYRIGHT: (C)1995,JPO