稀土铈对夹杂物特征的影响

Effects of Rare Earth Cerium on the Characteristics of Inclusions

通过试验冶炼稀土钢,采用扫描电镜与能谱仪,结合热力学计算分析稀土钢中夹杂物的成分以及形貌、尺寸分布等特征,研究稀土钢中夹杂物成分演变机理和稀土添加量对夹杂物特征的影响规律,从而实现稀土钢中夹杂物的精确控制。研究结果表明:在1 873 K时,稀土钢中CeAlO3和Ce2O2S夹杂物最为稳定。稀土钢中铈质量分数为0.015%时,冶炼过程中CeAlO3+CexSy夹杂物逐渐转变为Ce2O3,且夹杂物中Al2O3质量分数和CexSy质量分数降低。稀土钢中铈质量分数为0.028%时,夹杂物主要为Ce2O2S。冶炼初期稀土氧化物较多,随着钢液中溶解氧质量分数的降低,过剩的稀土Ce与硫结合,使得稀土硫化物逐渐增多。增加钢液中的铈含量,CeAlO3夹杂物减少,Ce2O2S增多。将铈含量从0.015%增加到0.028%时,夹杂物平均尺寸由2.83μm降低为2.66μm。

In order to precisely control the inclusions in rare earth steel,the compositions,morphologies and size distribution of inclusions in rare earth steel from a steelmaking experiment are analyzed by SEM-EDS and thermodynamic calculation,on which the composition evolution mechanism of inclusion and effects of rare earth addition on the characteristics of inclusions are studied.The results show that the inclusions of CeAlO3and Ce2O2S in rare earth steel are in the most stable state at 1 873 K.When the cerium content in the rare earth steel is 0.015%,the inclusions of CeAlO3+CexSy gradually change to the inclusions of Ce2O3,and the Al2O3 content and CexSy content in the inclusions decrease.When the cerium content in the rare earth steel is 0.028%,the inclusions are mainly Ce2O2S,inclusions and more rare earth oxides are produced at early melting stage.With the decrease of dissolved oxygen content in the molten steel,the excess rare earth element cerium combines with sulfur,which makes the rare earth sulfide increasing gradually.With the increase of cerium content in molten steel,the CeAlO3inclusions decrease and Ce2O2S inclusions increase.When the cerium content is increased from 0.015% to 0.028%,the average size of inclusions is decreased from 2.83 μm to 2.66 μm.