不锈钢熔体中氮溶解度的热力学计算模型

在实验研究和前人研究工作的基础上,建立了一个新的不锈钢熔体中氮溶解度与体系温度、氮分压和合金成分的热力学计算模型,在该模型中引入了氮分压对氮活度系数的作用系数.该模型的计算结果与实验值吻合很好.基于该模型的计算结果,讨论了氮分压、温度、合金成分对不锈钢熔体中氮溶解度的影响规律.在压力较高(大于0.1 MPa)特别是合金元素较高的不锈钢熔体中,氮分压与氮的溶解度关系不符合Sievert定律.在一定氮分压下,温度对不锈钢熔体中氮溶解度的影响取决于合金体系的化学成分.在常压(氮分压为0.1 MPa)下,20%Cr-20%Mn的合金体系在1 873 K可获得氮质量分数为0.8%的高氮无镍奥氏体不锈钢.

Thermodynamic Calculation Model of Nitrogen Solubility in Molten Stainless Steel

A new thermodynamic model was developed to calculate the nitrogen solubility in molten stainless steel,in a wide range of system temperature,nitrogen partial pressure and alloying constituents by introducing an interaction coefficient expressing the effect of nitrogen partial pressure on nitrogen activity coefficient on the basis of experiments and other authors' earlier works.The calculation results were in good agreement with measured values,with which the influences of nitrogen partial pressure,temperature and alloy constituents on the nitrogen solubility in molten stainless steels were discussed.Under high pressure especially the high concentration of alloying elements,it was found that the relationship between nitrogen solubility in liquid stainless steels and nitrogen partial pressure doesn't follow Sievert's law.The dependence of temperature on the nitrogen solubility is determined by the composition of alloying elements under a certain nitrogen partial pressure.The mass fraction of nitrogen in the 20%Cr-20%Mn alloy can be up to 0.8% at 1 873 K under normal pressure(N2 partial pressure=0.1 MPa).