稀土元素在洁净重轨钢中存在状态的热力学模型研究

A Study on Thermodynamic Model for Rare Earth Element Existence in Clean Heavy Rail Steel

建立了可以定量描述洁净稀土重轨钢凝固过程中成分偏析与夹杂物析出的耦合热力学模型,经文献验证,模型具有较高精度。通过模型分析了稀土加入量对洁净钢中夹杂物的析出规律与稀土存在状态的影响。得出在洁净重轨钢中加入稀土可以变质钢中MnS、Al_2O_3夹杂;钢中首先析出稀土氧硫化物(或稀土铝酸盐),其次是稀土硫化物,最后是稀土氮化物;在同一稀土加入量条件下,固溶La的量要大于固溶Ce的量。

A coupling thermodynamic model to quantitatively describe elements segregation and inclusions precipitation during solidification process of clean RE heavy rail steel has been established, and according to the analysis on literature data, the model has higher precision. The effect of RE adding amount on law of precipitation of inclusions and RE elements existence state in clean steel has been analyzed by the model. It is obtained that the MnS and Al2O3 inclusions in steel can be modified by adding RE elements in clean heavy rail steel; the RE oxysulfide （or RE aluminate） first precipitates in steel, then RE sulfide and last RE nitride; and with adding same RE elements amount, the lanthanum solute content is larger than the cerium solute content.