SCM420连铸坯热送过程MnS-AlN复合相的析出行为  

Precipitation behavior of MnS-AlN composite phase during hot charging of SCM420 continuous casting slab

作　　者：詹欣林 成国光 申文君 李尧 刘俊江[2] 郑宏光[2] ZHAN Xin-lin;CHENG Guo-guang;SHEN Wen-jun;LI Yao;LIU Jun-jiang;ZHENG Hong-guang(State Key Laboratory of New Technology of Iron and Steel Metallurgy,University of Science and Technology Beijing,Beijing 100083,China;Baoshan Iron and Steel Co.,Ltd.,Shanghai 201900,China)

机构地区：[1]北京科技大学钢铁冶金新技术国家重点实验室,北京100083 [2]宝山钢铁股份有限公司,上海201900

出　　处：《中国冶金》2022年第3期34-42,共9页China Metallurgy

基　　金：国家自然科学基金资助项目(51874034)。

摘　　要：为了研究SCM420连铸大方坯不同热送条件下铸坯表层MnS-AlN复合相的析出特征及形成机理,利用冷场发射电镜对MnS-AlN的三维形貌与分布特征进行了观察,对钢中AlN析出热力学、不同形核机制下的析出动力学特征进行了理论计算,分析了不同形貌MnS-AlN基底MnS的当量直径D与AlN相对析出量指标A的关系,最后得出了热送过程中3种形貌MnS-AlN的形成机理。研究结果表明,两相区热送条件下铸坯表层MnS-AlN的形貌有胚芽状(TypeⅠ)、长方体棒状(TypeⅡ)和六棱板状(TypeⅢ)3种;高温热送条件下铸坯表层MnS-AlN的形貌有胚芽状(TypeⅠ)和六棱板状(TypeⅢ)2种,大部分MnS-AlN位于晶界附近,少部分位于晶内。TypeⅠ、TypeⅡ、TypeⅢ3类MnS-AlN的基底MnS平均当量直径D依次递减,AlN相对析出量指标A依次递增。不同热送条件下,相同类型MnS-AlN的基底MnS尺寸以及AlN相对析出量指标A值相差不大。在热送过程中最先形成TypeⅠ类MnS-AlN,随后AlN在小尺寸的TypeⅠ类MnS-AlN上析出长大形成TypeⅡ和TypeⅢ类MnS-AlN。In order to study the precipitation characteristics and formation mechanism of the MnS-AlN composite phase on the surface of the SCM420 continuous casting bloom under different charging conditions,the three-dimensional morphology and distribution characteristics of MnS-AlN were observed by cold field emission electron microscope.The thermodynamics of AlN precipitation and the kinetic characteristics of precipitation under different nucleation mechanisms were theoretically calculated.The relationship between the equivalent diameter D of the MnS substrate with different morphologies of MnS-AlN and the relative precipitation index A of AlN were analyzed.Finally,the evolution law of the three morphologies of MnS-AlN during the hot charging process was obtained.In this study,the morphology of MnS-AlN on the surface of the cast slab under the condition of two-phase zone hot charging is germ-like(TypeⅠ),cuboid rod-like(TypeⅡ)and hexagonal plate-like(TypeⅢ).The surface MnS-AlN morphology of the cast slab under the condition of hot charging has germ-like(TypeⅠ)and hexagonal plate-like(TypeⅢ).Most of MnS-AlN is located near the grain boundary,only a small part is located in the grain.The average equivalent diameter D of the base MnS of TypeⅠ,TypeⅡ,and TypeⅢMnS-AlN decreases successively,and relative precipitation index A increases successively.Under different heat charging conditions,the size of base MnS of the same type of MnS-AlN and the relative precipitation index A value of AlN are almost the same.TypeI MnS-AlN is formed first during the hot charging process,and then AlN precipitates and grows into TypeⅡand TypeⅢMnS-AlN on the small-sized TypeI MnS-AlN.

关 键 词：SCM420 热送 MnS-AlN 三维形貌 形核机制 形成机理 

分 类 号：TF777.2[冶金工程—钢铁冶金]