钢液真空处理过程中Mn挥发动力学研究

Kinetic study of Mn evaporation during the vacuum treatment of molten steel

Mn作为提高钢材强度的主要元素之一,在钢液真空处理过程中的挥发会对钢材成分及质量控制产生不利影响,因此,明确钢液中Mn的挥发机理,并据此精确调控钢液中Mn含量,对于保证钢材质量显得尤为重要。本研究针对X80管线钢的真空精炼处理过程,分析了气相压强和熔炼温度对钢液中Mn挥发行为的影响。结果表明:随着熔炼温度的升高和气相压强的降低,钢液中Mn挥发速率明显加快;在熔炼温度1903 K、气相压强19 Pa、处理时间40 min条件下,Mn挥发率高达92.26%。在熔炼温度1823~1973 K、气相压强19~670 Pa条件下,Mn挥发遵循一级反应规律,其表观挥发速率常数在(0.41~26.56)×10^(-5)m/s范围内;在气相压强19~670 Pa、熔炼温度1903 K的条件下,Mn挥发主要受气相传质的限制;在气相压强226 Pa、熔炼温度1823~1973 K的条件下,Mn挥发的表观活化能达到120.20 kJ/mol,限制性环节为气-液界面反应;本研究条件下,液相传质对Mn挥发速率的影响较小。

Mn,as one of the primary elements enhancing the strength of steel,can adversely affect the composition and quality control of steels due to its evaporation during the vacuum treatment of molten steel.Therefore,elucidating the evaporation mechanism of Mn in molten steel and accurately controlling its content is crucial for ensuring the quality of steels.Focusing on the vacuum refining process of X80 pipeline steel,this paper investigated the effects of gas pressure and melting temperature on the evaporation behaviour of Mn in molten steel.The results reveal that the evaporation rate of Mn significantly increases with the increase of melting temperature and the decrease of gas pressure;under conditions of a melting temperature at 1903 K,a gas pressure at 19 Pa,and a treatment time of 40 min,the evaporation rate of Mn can reach as high as 92.26%.At melting temperatures ranging from 1823 to 1973 K and gas pressures from 19 to 670 Pa,the evaporation of Mn follows first-order reaction kinetics,with the apparent evaporation rate within the range of(0.41~26.56)×10^(-5) m/s.Under the conditions of gas pressure from 19 to 670 Pa and a melting temperature at 1903 K,Mn evaporation is primarily limited by gas phase mass transfer;at a gas phase pressure of 226 Pa and melting temperatures from 1823 to 1973 K,the apparent activation energy of Mn volatilization reaches 120.20 kJ/mol,with the limiting factor being the gas-liquid interface reaction.Under the current experimental conditions,the impact of liquid phase mass transfer on the Mn evaporation rate is minimal.