K439B铸造高温合金800℃长期时效组织与性能演变

Evolution of Microstructures and Mechanical Properties of K439B Superalloy During Long-Term Aging at 800℃

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中文摘要：对K439B合金开展800℃、3000 h长期时效,研究合金显微组织及力学性能的演变,分析室温拉伸及815℃、379 MPa持久性能的变形机制.结果表明:热处理态K439B合金中的γ'相呈球状,晶界存在MC及M23C6 2种碳化物,而枝晶间仅存在MC碳化物.在800℃长期时效过程中,γ'相的粗化遵循Ostwald熟化机制且形貌趋于立方化,γ'相粗化速率为71.7 nm3/h;晶界和枝晶间MC碳化物发生退化,M23C6碳化物析出含量逐渐增加.时效3000 h后晶界γ'相与M23C6碳化物存在[111]γ'//[111]M23C6、(22ˉ0)γ'//(22ˉ0)M23C6 的位向关系.热处理态合金的室温抗拉强度和屈服强度分别为1159.0和911.5 MPa,815℃、379 MPa持久寿命为150.4 h.长期时效后γ'相尺寸增加使得位错的运动方式由以位错在基体中滑移为主向位错切入γ'相为主转变,γ'相中出现了更多的堆垛层错,合金室温拉伸强度和815℃、379 MPa持久寿命均降低.

外文摘要：The K439B alloy is a novel equiaxed superalloy and is used for producing hot section components that need to resist high temperatures in aero engines and gas turbines as its temperature ca-pacity exceeds 800℃.In this study,the evolution of the microstructure and mechanical properties of K439B equiaxed superalloy after being subjected to long-term aging at 800℃ for 3000 h was examined.The predominant deformation mechanisms affecting room-temperature tensile and stress rupture proper-ties at 815℃ and under 379 MPa stress following different aging durations for the K439B alloy were inves-tigated.Results indicate that for heat-treated alloy,the morphology of the γ′ phase is spherical,MC carbide is generated in the interdendritic region and grain boundaries,while M23C6 carbide is in the grain boundar-ies.During long-term aging at 800℃,γ′ precipitates conform to the Ostwald ripening mechanism for growth and tend to take a cubic form;the coarsening rate of the γ′ phase is calculated to be 71.7 nm3/h;Additionally,the MC carbide deteriorates while the content of M23C6 carbide gradually increases.After long-term aging for 3000 h,the precipitated grain boundary phase comprises MC carbide,γ′ phase,and M23C6 carbide;the orientation relationship between γ′ phase and M23C6 carbide can be described as[111]γ′//[111]M23C6 and(22ˉ0)γ′//(22ˉ0)M23C6.The heat-treated alloy demonstrates room-temperature tensile and yield str-engths of 1159.0 MPa and 911.5 MPa,respectively.Meanwhile,the stress rupture life at 815℃ and under 379 MPa stress is 150.4 h.As the size of γ′ precipitates increases,the dominant deformation mechanism shifts from dislocation slipping in the matrix to dislocation cutting through the γ′ phase after long-term ag-ing,resulting in superior stacking faults appeared in the γ′ phase.Consequently,the room-temperature tensile strength and stress rupture life show reduction at 815℃ and under 379 MPa stress.

外文关键词：

K439Blong-term agingmicrostructuremechanical propertydeformation mechanism

作者：

张雷雷、陈晶阳、汤鑫、肖程波、张明军、杨卿

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作者单位：

西安理工大学材料科学与工程学院西安 710048

中国航发北京航空材料研究院先进高温结构材料重点实验室北京 100095

关键词：

K439B 长期时效显微组织力学性能变形机制

基金：

国家科技重大专项项目国家重点研发计划项目先进高温结构材料重点实验室基金先进高温结构材料重点实验室基金中国航空发动机集团科技创新平台项目

项目编号：

J2019-VI-0004-01172022YFB370680461429032101046142903220101CXPT-2018-006

出版年：

2023

DOI：

10.11900/0412.1961.2023.00141

金属学报

中国金属学会

金属学报

CSTPCDCSCD北大核心

影响因子：0.925

ISSN：0412-1961

年,卷(期)：2023.59(9)

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