镍基单晶高温合金定向凝固雀斑形成机理研究  

Investigation of Mechanism for Formation of Freckle during Directional Solidification of Ni Base Single Crystal Superalloy

作　　者：吴怀洲 玄伟东 张翔宇 段方苗 任兴孚 马德新 任忠鸣 WU Huaizhou;XUAN Weidong;ZHANG Xiangyu;DUAN Fangmiao;REN Xingfu;MA Dexin;REN Zhongming(State Key Laboratory of Advanced Special Steel,Shanghai Key Laboratory of Advanced Ferrometallurgy,School of Materials Science and Engineering,Shanghai University,Shanghai 200444,China;China United Gas Turbine Technology Co.,Ltd.,Beijing 100061,China;Wedge Central South Research Institute,Shenzhen 518004,China)

机构地区：[1]上海大学材料科学与工程学院省部共建高品质特殊钢冶金与制备国家重点实验室上海市钢铁冶金新技术应用重点实验室,上海200444 [2]中国联合重型燃气轮机技术有限公司,北京100061 [3]深圳市万泽中南研究院有限公司,广东深圳518004

出　　处：《热加工工艺》2025年第3期120-124,共5页Hot Working Technology

基　　金：国家重大科技专项项目(2017-VII-0008-0102);国家自然科学基金资助项目(92060104);上海市科委项目(20511107700);中国重燃项目(F035)。

摘　　要：对单晶高温合金熔模组铸件定向凝固过程中产生的雀斑缺陷进行了实验研究和理论分析。结果表明,雀斑缺陷容易出现在铸件的加热侧,组织中存在较多取向随机的等轴晶晶粒,平均尺寸为340μm;并且试样从背阴侧到加热侧再到雀斑区域,共晶含量逐渐增多,分别为1.21%、2.53%和5.41%。分析认为在熔模组铸造过程中铸件处于不对称的温度场下,受温度梯度下的区熔现象(TGZM效应)的影响,铸件加热侧的糊状区形成溶质富集,使加热侧枝晶的元素偏析程度大于背阴侧枝晶,增加了铸件加热侧熔体发生对流的倾向性,促进了雀斑缺陷在加热侧形成。The freckle defect formed during directional solidification of single crystal superalloy investment casting cluster were investigated by experiment and theroy analysis.It is found that freckles tend to form at the heating side of the specimens rather than the shadow side.The freckle defects contain a large amount of equiaxed grains with random orientations and the average grain size of freckles is 340μm.The eutectic content increases gradually from the shadow side to the heating side finally to the the freckle zone of the specimen,which is 1.21%,2.53%and 5.41%,respectively.Based on the detection and theoretical analysis of freckle defects,it is considered that the unsymmetrical thermal condition will lead to solute enrichment at the heating side of the specimens due to the temperature gradient zone melting(TGZM).The solidification segregation of the dendrites at the heating side is more severe than the shadow side.This phenomenon increases the tendency of convection and flow in the mushy zone of the heating side,and promotes the formation of freckle defects.

关 键 词：高温合金 雀斑 定向凝固 温度场 熔模组 

分 类 号：TG27[金属学及工艺—铸造] TG132.32[一般工业技术—材料科学与工程]