CONTROLLING METHOD FOR NITROGEN CONTENT IN BLOWING OUT STEEL AT BOTTOMMBLOWN CONVERTER REFINING

摘要

PURPOSE:To control the nitrogen content with a high yield, by blowing nitrogen in the bottom-blown converter within the limits of 0.1-0.7% of carbon content in the steel at the time of manufacturing nitrogen contained steel in the above converter. CONSTITUTION:On occasion of refining steel by oxygen blowing the bottom-blown converter, sample is picked out at the closing stage of blowing and carbon content is analyzed quickly. Oxygen blowing is stopped for a while when the carbon content is made within the limits of 0.1-0.7% and nitrogen is blown from the tuyere of furnace bottom and then, is absorbed so as to contain aimed nitrogen. Next, oxygen blowing is carried out again and decarbonizing refining is carried out so as to contain the aimed nitrogen content. The steel containing aimed C and N, is manufactured without lowering the nitrogen content at the time of blowing out. Absorptivity of nitrogen is good and the nitrogen content by oxygen blowing is not lowered nearly and then, hitting rate of the nitrogen content is improved when nitrogen is blown within the limit of 0.1-0.7% of C content.