Abstract: Increasing nitrogen by blowing nitrogen at the bottom of the furnace is an effective nitrogen alloying method which can save the nitrogen alloy and reduce the cost. The factors of the solubility of nitrogen in steel were analyzed by theoretical calculation, and the technological conditions of the time and pressure of the ladle bottom blowing were determined, then the experiments of industrialization have been carried out. The results showed that the mass fraction of nitrogen increased with the increase of pressure and flow rate, the nitrogen pressure increased by 0.2MPa and the solubility of nitrogen increased by 25×10-6, but the impact of the flow is far from the pressure. The steel whose nitrogen mass fraction was （100-150)×10-6 could be producted by means of bottom blowing nitrogen without adding nitrogen nitride.

Key words: steelmaking, nitrogen alloying, thermodynamics, LF, bottom blowing