| 摘要 |
PURPOSE:To control the content of N in killed steel in the stage of tapping under continuation of blowing of an inert gas into a steel bath after oxygen blowing in a converter having a bottom blowing function by controlling the timing for adding Al during tapping. CONSTITUTION:Oxygen is blown through the inside pipes of the double pipe tuyeres 3 in the bottom 2 of a furnace body 1, and propane or the like through the clearances of the outside pipes simultaneously into molten iron, whereby oxygen blowing is effected. After the prescribed blowing-out is attained, blowing or Ar or N2 through the tuyeres 3 is continued to dehydrogenate and deoxidize the molten iron; thereafter the body 1 is tilted to tap molten steel 4 into a ladle 6. Al is added through a chute 7 in this time, and since the influence of the timing of addition of the Al upon the absorption of nitrogen by tapping is as shown in the figure, the amt. of nitrogen is controlled if the timing for addition of the Al is controlled. |
