特殊钢中稀土变质夹杂物行为研究

Behavior of Rare Earth on Modifying Inclusion in Special Steel

通过加入稀土金属（Ce）,研究不同稀土含量对变质夹杂物的影响。发现在洁净度较高的A l脱氧特殊钢中稀土能够使氧化铝、硫化锰夹杂变质并能形成硬度较低的铝酸稀土夹杂物。研究结果表明：当稀土含量Ce〈15 ppm时,钢中没有稀土夹杂物;当15 ppm≤Ce≤140 ppm时,能够生成稀土铝氧化物和稀土硫氧化物夹杂物;当Ce〉140 ppm时,夹杂物进一步转变为稀土铝氧化物和稀土氧硫化物的复合夹杂物,并有部分稀土氧硫化物和稀土硫化物,夹杂物的尺寸也随着增大。热力学分析计算表明：在[O],[S]含量较低的前提下,Ce变质A l2O3所需的条件是aCe.aA-l1=0.145,当[A l%]=0.01~0.03时,对应溶解的稀土含量[Ce]=22~67 ppm。

Effects of different content of RE on modifying inclusion were studied by adding cerium.It was discovered that RE could modify alumina and manganese sulfide into RE aluminates with lower hardness in Al-killed special steel with high cleanness.It was found that there was no rare-earth inclusions in steel when the content of Ce〈15 ppm;as 15 ppm≤Ce≤140 ppm,the RE aluminates and rare earth oxysulfide were generated;as Ce〉140 ppm,the inclusions further turned into complex inclusions of cerium aluminates and rare earth oxysulfide,as well as some rare earth sulfides and rare earth oxysulfide,also with increasing of size of the inclusions.The thermodynamic analysis indicated that the cerium could modify alumina when the contents of oxygen and sulfur were at low levels,the ratio of activity of Ce and Al should exceed 0.145,and cerium should be between 22 and 67 ppm when =0.01%~0.03%.