稀土铈对20CrMnTi钢中TiN相析出热力学计算及分析  

Thermodynamic calculation and experimental analysis on effects of rare earth Ce on TiN phase precipitation in 20CrMnTi steel

作　　者：王健[1,2] 彭军[1,2,3,4] 张芳 彭继华[1,2,3] 刘爽[1,2,3] 安胜利 WANG Jian;PENG Jun;ZHANG Fang;PENG Jihua;LIU Shuang;AN Shengli(School of Materials and Metallurgy,Inner Mongolia University of Science and Technology,Baotou 014010,Nei Mongol,China;Inner Mongolia Key Laboratory of Advanced Ceramic Materials and Devices(Inner Mongolia University of Science and Technology),Baotou 014010,Nei Mongol,China;Key Laboratory of Green Extraction and Efficient Utilization of Light Rare-Earth Resources,Ministry of Education(Inner Mongolia University of Science and Technology),Baotou 014010,Nei Mongol,China;School of Rare Earth Research and Development,Inner Mongolia University of Science and Technology,Baotou 014010,Nei Mongol,China)

机构地区：[1]内蒙古科技大学材料与冶金学院,内蒙古包头014000 [2]内蒙古自治区先进陶瓷材料与器件重点实验室(内蒙古科技大学),内蒙古包头014010 [3]教育部轻稀土资源绿色提取与高效利用重点实验室(内蒙古科技大学),内蒙古包头014010 [4]内蒙古科技大学稀土产业学院,内蒙古包头014010

出　　处：《钢铁》2024年第4期66-73,84,共9页Iron and Steel

基　　金：国家自然科学基金资助项目(52264044);内蒙古自治区自然科学基金资助项目(2022L HMS05009,2022MS05017)。

摘　　要：TiN夹杂物尺寸和形貌对20CrMnTi齿轮钢产品质量、服役性能均有影响,控制TiN析出尺寸及形貌是提高20CrMnTi钢服役稳定性的关键。利用计算及试验等方法,对添加稀土铈元素前后20CrMnTi钢中TiN夹杂形核行为进行了研究。并对钢中夹杂物形貌、种类、尺寸等进行了表征及统计分析;研究了稀土铈对20CrMnTi钢中TiN夹杂物改质的行为机理。结果表明,热力学计算TiN析出温度为1744 K。温度为1873 K时,钢液中无法析出TiN等夹杂物,即TiN只能在钢液凝固过程中析出长大。当钢中钛质量分数大于0.03%时,Ti-N平衡趋于平缓,温度对其析出影响相对较小,并且20CrMnTi钢中析出的TiN易富集长大形成大尺寸含钛夹杂物。加入稀土铈元素后,钢中会形成Ti、O、Ce、Al、N等元素富集的复合相,该复合相棱角收缩,外形为球形或者椭球形状,较TiN、Al_(2)O_(3)-TiN夹杂物尺寸更小。经相鉴定分析可知,该复合相为钢中稀土铈与Al_(2)O_(3)反应生成的CeAlO_(3),可作为TiN夹杂物的形核核心,形成椭球型的CeAlO_(3)-TiN复合夹杂物,进而达到改质含钛夹杂物的目的。铈元素加入后,钢中含TiN夹杂物总面积并没有减小,但形成了更为细小的含TiN复合相CeAlO_(3)-TiN。因形成尺寸更小的复合夹杂物CeAlO_(3)-TiN,使钢中尺寸大于5μm夹杂物占比降低了17.2%,细化了钢中含TiN夹杂物,有效减小了钢中TiN夹杂物尺寸,从形貌和尺寸上,达到改质钢中TiN的效果。The size and morphology of TiN inclusions have an effect on the quality and service performance of gear steel 20CrMnTi.Controlling the size and morphology of TiN precipitation is the key to improving the service stability of 20CrMnTi.The nucleation behaviors of TiN inclusions in 20CrMnTi before and after the addition of rare earth Ce element was studied by the calculations and experiments.The morphologies,types and sizes of the inclusions were characterized and analyzed statistically.The behavior mechanisms of rare earth Ce on the modifications of TiN inclusions in 20CrMnTi were studied.The results show that TiN precipitation temperature calculated by thermodynamics is 1744 K.TiN inclusions cannot precipitate in the molten steel at 1873 K.TiN can only precipitate and grow during the solidification of the steel.After the additions of rare earth Ce,a composite phase enriched with Ti,O,Ce,Al and N elements will be formed in the steel.The composite phase is angular contracted,and the shape is spherical or ellipsoid,smaller than TiN and Al_(2)O_(3)-TiN inclusions.Through phase identification analysis,it can be seen that the composite phase is CeAlO_(3) produced by the reaction of rare earth Ce and Al_(2)O_(3) in steel,which can be used as the nucleation cores of TiN inclusions to form the ellipsoidal CeAlO_(3)-TiN,and then achieve the purpose of modifying titanium-containing inclusions.After the addition of Ce element,the total areas of TiN-containing inclusions in steel does not decrease,but a smaller CeAlO_(3)-TiN is formed.Due to the formations of the smaller composite inclusions of CeAlO_(3)-TiN,the number of inclusions with a size larger than 5μm reduces by 17.2%,and refines TiN containing inclusions in steel.The addition of Ce effectively reduces the size of TiN inclusions in steel,and achieves the effect of modifying TiN in terms of morphology and size.

关 键 词：齿轮钢 稀土铈 微合金化 夹杂物 形核核心 

分 类 号：TG142.1[一般工业技术—材料科学与工程]