| 摘要 |
PURPOSE:To execute addition of nitrogen in a converter having bottom blowing tuyere, while the nitrogen concn. in molten steel is accurately restrained during blowing out by blowing N2 gas or mixed gas containing N2 gas from the bottom in accordance with the prescribed oxygen concn. and the aimed blowing out nitrogen concn. into the molten steel. CONSTITUTION:In the addition of nitrogen in the converter having the bottom blowing tuyere, the relation between the oxygen concn. in the molten steel during blowing and the yield of nitrogen, is shown in the figure. That is, the yield of nitrogen is increased in accordance with decreasing the oxygen concn. in the molten steel, but in the range of <=50ppm oxygen concn., dispersion of the yield of nitrogen increase. Therefore, in order to execute control of nitrogen concn. in the molten steel with good accuracy, it is necessary to blow N2 gas at the time oxygen concn. in the molten steel is >=50ppm. On the other hand, in case the oxygen conc. is >=300ppm, the dispersion of the yield of nitrogen is decreased, to value of <=3.0%. Therefore, an oxygen concn. range of 50-300ppm in the molten steel is suitable in case of blowing of N2 gas. In this way, the high nitrogen contained steel, in the converter is rapidly and economically produced with small dispersion.
|
