Experimental study on deep denitrogenation of molten steel via vacuum coupled with carbon-oxygen reaction

WU Huajie; LIU Zuoyu; SUN Yue; ZHANG Ke; HUO Jiaxing; XU Jialong

doi:10.7513/j.issn.1004-7638.2026.04.010

Volume 47 Issue 4

Aug. 2026

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WU Huajie, LIU Zuoyu, SUN Yue, ZHANG Ke, HUO Jiaxing, XU Jialong. Experimental study on deep denitrogenation of molten steel via vacuum coupled with carbon-oxygen reaction[J]. IRON STEEL VANADIUM TITANIUM, 2026, 47(4): 85-91, 108. doi: 10.7513/j.issn.1004-7638.2026.04.010

Citation:

WU Huajie, LIU Zuoyu, SUN Yue, ZHANG Ke, HUO Jiaxing, XU Jialong. Experimental study on deep denitrogenation of molten steel via vacuum coupled with carbon-oxygen reaction[J]. IRON STEEL VANADIUM TITANIUM, 2026, 47(4): 85-91, 108. doi: 10.7513/j.issn.1004-7638.2026.04.010

Citation:

WU Huajie, LIU Zuoyu, SUN Yue, ZHANG Ke, HUO Jiaxing, XU Jialong. Experimental study on deep denitrogenation of molten steel via vacuum coupled with carbon-oxygen reaction[J]. IRON STEEL VANADIUM TITANIUM, 2026, 47(4): 85-91, 108. doi: 10.7513/j.issn.1004-7638.2026.04.010

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Experimental study on deep denitrogenation of molten steel via vacuum coupled with carbon-oxygen reaction

doi: 10.7513/j.issn.1004-7638.2026.04.010

Collaborative Innovation Center of Steel Technology, University of Science and Technology Beijing, Beijing 100083, China

More Information

Received Date: 2026-03-03
Accepted Date: 2026-03-12
Rev Recd Date: 2026-03-10
Publish Date: 2026-08-31

Abstract

Abstract

Excessively high nitrogen content in steel significantly deteriorates its mechanical properties and subsequent processing performance. Achieving stable and efficient deep denitrogenation is a key technical challenge in producing high-quality steel during the converter and electric arc furnace steelmaking processes. This study, utilizing experiments in a 10 kg vacuum induction furnace, proposes and validates a method to enhance deep denitrification in molten steel by coupling carbon-oxygen reactions to generate endogenous CO bubbles under vacuum conditions. The effects of carbon-oxygen reaction intensity and initial nitrogen content on the denitrification behavior were systematically investigated and analyzed from both thermodynamic and kinetic perspectives. The results indicate that under vacuum conditions, the endogenous CO bubbles generated by the carbon-oxygen reaction significantly increase the gas-liquid reaction interface, thereby greatly enhancing the denitrification efficiency. As the intensity of the carbon-oxygen reaction increases, the denitrification rate of the molten steel accelerates markedly. With an initial carbon content of 1500×10^-6, the nitrogen content in the steel can be reduced to below 10×10^-6 within 10 minutes. Under the same carbon-oxygen reaction intensity, the initial nitrogen content does not significantly affect the denitrification rate but plays a decisive role in determining the final nitrogen content. Thermodynamic calculations show that the minimum nitrogen content achieved in the experiments is close to the equilibrium solubility under a vacuum of 30 Pa. Kinetic analysis reveals that the denitrification process is controlled by a mixed mechanism involving liquid-phase mass transfer and interfacial chemical reactions. A quantitative relationship was established at the experimental scale, showing that the denitrification rate is proportional to the 2/3 power of the decarburization rate. The study also found that in the ultra-low nitrogen range, as the carbon-oxygen reaction weakens, the molten steel's behavior can easily shift from denitrification to nitrogen absorption, necessitating strict control of vacuum conditions during the later stages of denitrification. The findings of this paper provide a theoretical basis and experimental reference for optimizing deep denitrification processes in vacuum refining processes.
- denitrogenation,
- carbon-oxygen reaction,
- kinetics,
- internal bubbles,
- vacuum

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References(27)

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