碲处理控制Y15易切削钢中MnS夹杂物形貌

 为了研究碲对钢中MnS夹杂物形貌的影响，针对Y15高硫易切削钢，利用SEM-EDS扫面电镜，结合FactSage热力学计算，分析了不同碲质量分数对钢中MnS夹杂物形貌、尺寸、长宽比的影响，同时探讨了稀散金属碲对MnS夹杂物形貌控制的机理。研究结果表明，钢液中加碲后，在MnS夹杂物的外环形成了碲、锰、铁的复合相。钢中加碲后MnS夹杂物的形貌和分布大幅度改变，当碲硫比为0.05时，链状MnS夹杂物大幅度减少，球状MnS夹杂物数量增加；当碲硫比增加到0.2时，链状MnS夹杂物基本消失；当碲硫比增加到0.5时，MnS夹杂物形貌的变化不再明显。钢中加碲显著降低了MnS夹杂物的长宽比，控制MnS夹杂物长宽比最合适的碲硫比为0.2。FactSage计算结果表明，MnTe的生成温度为1 900 ℃，在MnS的析出温度下，MnTe是作为液态夹杂物存在的。在凝固过程中，MnTe和MnS发生固溶现象，由于MnTe为液态，两者形成的固溶体会趋于球形生长。

Morphology of MnS inclusions in Y15 high sulfur free-cutting steel by tellurium treatment

For the purpose of investigating tellurium on the morphology of MnS in steel,aiming at Y15 high sulfur free-cutting steel,using scanning electron microscopy,combined with FactSage thermodynamic calculation,the effect of tellurium on morphology,size and aspect of MnS inclusions in steel was studied and the controlling mechanism of scat-tered metals tellurium in the morphology of MnS inclusions was discussed.The results show that,after tellurium added into liquid steel,the compound which is identified as complex phase containing Fe,Mn and Te by elementmapping forms. The morphology and distribution of MnS changes significantly by adding Te into liquid steel.MnS inclusions of chain shapearegreatly reduced and quantities of globular MnS inclusions increase when the ratio of Te content to S con-tent reaches 0.05. MnS inclusions of chain shape almost entirely disappear when the ratio of Te content to S content reaches 0.2,andthe change of MnS inclusions morphologyis no longer obvious when w(Te)/w(S) reaches 0.5. The aspect of MnS inclusions reduces significantly by adding Te into liquid steel and the best ratio to control MnS inclusions is 0.2. FactSage calculation shows that the formation temperature of MnTe is 1900℃.Solid solution occurs between MnS and MnTe during solidification. Solid solution growsspherical because of liquid MnTe.