含Ce 7Mo超级奥氏体不锈钢凝固组织及夹杂物分析研究  

Solidification microstructure evolution and inclusion analysis of Ce-containing 7Mo super-austenitic stainless steel

作　　者：王旗 杜越 王丽君[2] 张威 郑亚旭 鲁素玲[1] 朱立光 WANG Qi;DU Yue;WANG Lijun;ZHANG Wei;ZHENG Yaxu;LU Suling;ZHU Liguang(College of Materials Science and Engineering,Hebei University of Science and Technology,Shijiazhuang 050018,Hebei,China;University of Science and Technology Beijing,Beijing 100083,China;Baowu Group,Taiyuan 030003,Shanxi,China)

机构地区：[1]河北科技大学材料科学与工程学院,河北石家庄050018 [2]北京科技大学,北京100083 [3]宝武集团太原钢铁集团,山西太原030003

出　　处：《钢铁钒钛》2025年第1期124-132,共9页Iron Steel Vanadium Titanium

基　　金：河北省自然科学基金(E2021208017);国家自然科学基金(52204341);河北省钢铁联合基金(E2021208006)。

摘　　要：采用稀土Ce处理是超级奥氏体不锈钢凝固组织调控研究的热点,系统分析了中试500 kg级Ce处理7Mo超级奥氏体不锈钢凝固相组织、夹杂物演变、元素偏析行为,为Ce处理7Mo超级奥氏体不锈钢提供理论依据。结果表明,7Mo超级奥氏体不锈钢非平衡凝固路径为L→L+γ→L+γ+δ→L+γ+δ+σ→L+γ+σ→L+γ+σ+Cr_(2)N。降温凝固过程中存在中间相δ相,凝固末期δ相会分解成σ相和γ_(2)相。钢中主要析出第二相为富Cr和Mo的σ相,铸态凝固组织由奥氏体相和σ相组成。7Mo超级奥氏体不锈钢Ce处理后,铸锭中的夹杂物主要为AlCeO_(3)和Al_(11)O_(18)Ce组成的复合夹杂物,其具有低错配度AlCeO_(3)结构,可以作为异质形核核心。降温凝固过程中Al脱氧能力增强,脱氧反应平衡被打破,导致Al_(11)O_(18)Ce包裹AlCeO_(3)形貌的夹杂物生成。铸锭芯部微观晶粒粗大,枝晶间微观偏析严重,微观晶粒尺寸是影响枝晶间微观偏析的核心因素,微观凝固组织晶粒尺寸降低可以有效改善晶粒内部各元素的偏析程度,降低枝晶间σ相中Mo、Cr含量。Rare earth Ce treatment is a hot topic in the modification of solidification microstructure for super austenitic stainless steel.In this study,the solidification phase structure,evolution of inclusions,and element segregation behavior of a 500 kg scale Ce-treated 7Mo super austenitic stainless steel were systematically analyzed,for the purpose of providing theoretical basis for Ce treatment of 7Mo super austenitic stainless steel.The results show that the non-equilibrium solidification path of 7Mo super austenitic stainless steel is L→L+γ→L+γ+δ→L+γ+δ+σ→L+γ+σ→L+γ+σ+Cr_(2)N.During cooling and solidification process,an intermediate phaseδphase exists,and theδphase decomposes intoσphase andγ_(2) phase at the end of solidification.The main second phase precipitated in the steel is theσphase rich in Cr and Mo,resulting in a cast solidification structure composed of austenite andσphase.After Ce treatment in super austenitic stainless steel,the inclusions in the ingot are mainly composite inclusions composed of AlCeO_(3) and Al_(11)O_(18)Ce,with a low mismatch AlCeO_(3) structure,which can serve as heterogeneous nucleation cores.During cooling and solidification process,the deoxidation ability of Al is enhanced,and the equilibrium of deoxidation reaction is broken,resulting in the generation of inclusions with Al_(11)O_(18)Ce encapsulating AlCeO_(3) morphology.The microstructure of the ingot core is coarse,with severe microsegregation between dendrites.The size of micro grains is the key factor affecting the microsegregation between dendrites,and reducing the size of micro solidification structure grains can effectively improve the degree of element segregation inside the grains and then reduce Mo and Cr content in theσphase between dendrites.

关 键 词：7Mo超级奥氏体不锈钢 凝固偏析 热力学计算 夹杂物 

分 类 号：TF771[冶金工程—钢铁冶金]