摘要
针对第4代粉末高温合金FGH4108,开展不同温度、不同保载时间下的疲劳裂纹扩展实验和中断实验研究,并结合扫描电子显微镜(SEM)、电子背散射衍射(EBSD)、电子探针X射线显微分析(EPMA)等表征手段分析温度和保载时间对裂纹扩展行为的影响,揭示氧化损伤对裂纹扩展的影响机理,提出1种描述机械-氧化耦合作用的疲劳裂纹扩展速率模型。结果表明:随着温度和保载时间增加,裂纹扩展速率上升,疲劳寿命显著下降;断面特征分析发现,在650℃时疲劳裂纹主要呈现穿晶扩展、断面平整,在750℃以上时疲劳裂纹主要呈现沿晶扩展、并伴随着二次裂纹的形成;同时,裂纹扩展过程中还伴随有尖端形貌改变与氧化物生成等现象,揭示了氧化作用对裂纹扩展的影响。提出的模型可以较好地描述不同温度与保载时间下的疲劳裂纹扩展速率,同时解耦了机械损伤、氧化损伤对裂纹扩展的影响,并确定了氧化损伤参数的温度相关性。
Fatigue crack growth experiments and interrupted tests are conducted on the fourth-generation powder metallurgy superalloy FGH4108 under varying temperatures and dwell time.The influence of temperature and dwell time on crack growth behavior is analyzed using characterization techniques such as Scanning Electron Microscopy(SEM),Electron Backscatter Diffraction(EBSD),and Electron Probe Microanalysis(EPMA).The mechanism by which oxidation damage affects crack growth is revealed.A fatigue crack growth rate model describing the mechanical-oxidation coupling effect is proposed.The results show that as temperature and dwell time increase,the crack growth rate rises and fatigue life decreases significantly.Fractographic analysis reveals that at 650℃,fatigue cracks primarily propagate transgranularly with relatively flat fracture surfaces,while at temperatures above 750℃,fatigue cracks mainly propagate intergranularly,accompanied by the formation of secondary cracks.Concurrently,phenomena such as alterations in crack tip morphology and oxide formation were observed during crack propagation,elucidating the im-pact of oxidation on crack growth.The proposed model can better describe the fatigue crack growth rate at different temperatures and dwell time.At the same time,the effects of mechanical damage and oxidative damage on crack growth are decoupled,and the temperature dependence of oxidative damage parameters is determined.
作者
秦豪
刘强
江荣
宋迎东
张强
刘建涛
邓健
卢天健
QIN Hao;LIU Qiang;JIANG Rong;SONG Yingdong;ZHANG Qiang;LIU Jiantao;DENG Jian;LU Tianjian(MIIT Key Laboratory of Multifunctional Lightweight Materials and Structures,Nanjing University of Aeronautics and Astronautics,Nanjing 210016,China;MIIT Key Laboratory of Aero-engine Thermal Environment and Structure,Nanjing University of Aeronautics and Astronautics,Nanjing 210016,China;High Temperature Material Institute,Central Iron and Steel Research Institute,Beijing 100081,China)
出处
《航空学报》
北大核心
2025年第21期117-130,共14页
Acta Aeronautica et Astronautica Sinica
基金
国家自然科学基金(12272174)
国家科技重大专项(2017-Ⅵ-0008-0078)
江苏省双创团队(JSSCTD202206)
江苏省自然科学基金(BK20220136)
航空发动机及燃气轮机基础科学中心重点项目(P2022-B-Ⅲ-007-001)。
关键词
粉末高温合金
氧化损伤
疲劳裂纹扩展
裂纹扩展速率模型
高温
powder metallurgy superalloy
oxidation damage
fatigue crack propagation
crack propagation rate model
high temperature
