METHOD FOR MANUFACTURING ULTRA LOW CARBON STEEL BY INGOT TECHNIQUES USING VACUUM-DEGASSING SYSTEM

摘要

An object of the present invention is to make it possible to advantageously shorten vacuum-degassing processing time, without causing decarburization failure and/or decrease in purity of molten steel, by adequatel increasing temperature of the molten steel in a degassing chamber by adding heat-generating agent thereto, while oxygen gas is being introduced into the degassing chamber, during decarburization process in manufacturing ultra low carbon steel byt ingot techniques using a vacuum-degassing system. Specifically, the present invention provides a method for manufacturing ultra low carbon steel by using vacuum-degassing system, comprising carrying out a decarburization process of molten steel by adding an amount of oxygen required for decarburization of the molten steel in a vacuum-degassing chamber, characterized in that the decarburization process further comprises:adding an amount of oxygen required for combusting a heat-generating agent to be added for heating the molten steel; adding the heat-generating either during or after said further addition of oxygen to heat the molten steel; and continuing the decarburization of the milten steel.