高铁扣件弹簧钢中含Ce夹杂物生成的热力学分析

摘要

通过热力学计算研究稀土Ce夹杂物在高铁扣件弹簧钢中生成的热力学条件，并分析加入稀土Ce对Al2O3夹杂的变质作用及条件。由稀土Ce硫化物、氧化物和氧硫化物的标准吉布斯生成自由能构建了稀土Ce夹杂物的空间析出图，并将其应用在预测高铁扣件弹簧钢中加入稀土Ce后夹杂物的生成顺序，并确定其存在形式及热力学转换条件。计算结果表明：钢液中加入稀土最容易生成的是CeAlO3夹杂，其次是Ce2O2S；在本计算所用钢种的氧活度和硫活度分别为0.000639和0.005845的条件下，钢液中首先会析出Ce2O2S；当钢液中Al含量为0.013%时，稀土变质Al2O3夹杂的理论加入量为0.0019%。%Thermodynamic condition of rare earth cerium inclusion formed in spring steel used in fastener of high­speed railway was studied by the thermodynamic calculation. In addition, the effect and condition of rare earth cerium on modifying Al2O3 inclusion were analyzed. Through the standard Gibbs free energies of formation of the sulfides, oxides and oxysulfides of cerium, the precipitation diagram in space was built. And it was applied to predict the sequence of rare earth inclusion formed the spring steel. Finally, the ultimate state of rare earth inclusions and their thermodynamic transformation condition were determined. The computation results show that the most easily formed inclusion is CeAlO3 when rare earth element Ce is added to the molten steel, with Ce2O2S following. In this work, when the activities of oxygen and sulfur in the steel are 0.000 639 and 0.005 845, respectively, the first precipitated inclusion is Ce2O2S. Moreover, when the aluminum content in the steel is 0.013%, the theoretic amount of added rare earth Ce is 0.0019%, which can realize Al2O3 deformation.