Renitrogenation of basic-oxygen steels during decarburization

Claim 1

In a process for the production of steel by decarburizing a ferrous melt contained in a vessel by blowing oxygen into the melt from above the surface thereof, the improvement comprising: producing steel having a high nitrogen content, within a preselected range by: (a) introducing a nitrogen-rich gas into the melt, simultaneously with said oxygen during the latter portion of the decarburization step, in an amount at least equal to 100 NCF of nitrogen gas per ton of molten metal, and in such 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 at least as low as 0.10 percent, 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 molten metal at 1600° C.