RENITROGENATION OF BASIC-OXYGEN STEELS DURING DECARBURIZATION

摘要

11,323 RENITROGENATION OF BASIC-OXYGEN STEELS DURING DECARBURIZATION Basic-oxygen steels containing a high, controlled level of nitrogen are made by: (a) introducing a nitrogen-rich gas into the melt during the latter portion of the decarburization step, through the oxygen lance together with the oxygen, in an amount sufficient to impart at least 100 NCF of nitrogen per ton of molten metal, and in such a manner as to promote intensive interaction of the nitrogen-rich gas with the molten metal, (b) refining the melt with the oxygen and nitrogen-rich gas by blowing the melt to a final manganese content of 0.10 percent or less, and (c) maintaining the partial pressure of nitrogen in the vessel head-space at least equal to that calculated to be in equilibrium with the aim dissolved nitrogen content of the melt at 1600.degree.C.