工程科学学报，第40卷，第7期：822-832,2018年7月 Chinese Journal of Engineering,Vol.40,No.7:822-832,July 2018 DOI:10.13374/j.issn2095-9389.2018.07.008;http://journals.ustb.edu.cn GH4169合金高温疲劳裂纹扩展的微观损伤机制 侯 杰，董建新四，姚志浩 北京科技大学材料科学与工程学院，北京100083 区通信作者，E-mail:jxdong@usth.cdu.cm 摘要空气环境对高温合金在高温下的损伤行为有显著影响.为了研究标准热处理态GH4169合金在高温疲劳裂纹扩展 过程中的微观损伤机制，在空气环境中进行650℃、初始应力强度因子幅△K=30MPa·m2和应力比R=0.05的低周疲劳裂纹 扩展试验.使用扫描电镜(SEM)及能谱(EDS)对试样的断口、外表面和剖面进行观察和分析.实验结果表明：疲劳主裂纹以 沿晶方式萌生并扩展，随后沿晶二次裂纹出现，并且其数量和长度沿主裂纹方向逐渐增加，进入快速扩展阶段后，断口呈现韧 窝组织形貌：在裂纹扩展过程中，δ相与基体的界面发生氧化，使得沿晶二次裂纹沿界面扩展并产生偏折，从而起到阻碍二次 裂纹扩展的作用：试样外表面的主裂纹周围出现晶界氧化损伤区，其尺寸和晶界开裂程度沿主裂纹扩展方向逐渐增大 关键词GH4169合金：高温；裂纹扩展；晶界氧化；8相 分类号TG146.1 Microscopic damage mechanisms during fatigue crack propagation at high temperature in GH4169 superalloy HOU Jie,DONG Jian-xin YAO Zhi-hao School of Materials Science and Engineering,University of Science and Technology Beijing,Beijing 100083.China Corresponding author,E-mail:jxdong@ustb.edu.cn ABSTRACT The air environment strongly influences the damage behaviors of superalloys at high temperatures.To investigate the mi- croscopic damage mechanisms during high-temperature fatigue crack growth in standard heat-treated GH4169 superalloys,low-cycle-fa- tigue crack growth tests were conducted at 650C with initial stress intensity factor AK=30 MPa.m2 and stress ratio R=0.05 under the air environment.The fracture surface,outside surface,and central sectioned surface of the specimen were observed and analyzed u- sing scanning electron microscopy (SEM)and energy-dispersive spectrometry (EDS).The results show that the main fatigue crack ini- tiates and propagates intergranularly,followed by the appearance of intergranular secondary cracks,whose quantity and length increase along the propagating direction of the main crack.In the rupture stage,a dimpled morphology appears on the fracture surface.Oxida- tion occurs at the interfaces between 8 phases and the matrix during the fatigue crack propagation process,which leads to secondary cracks propagating along the interfaces.This leads to their inflection,which in turn retards their propagation.A grain-boundary oxida- tion damage zone exists at the outside surface of the specimen near the main crack.The size and degree of grain-boundary cracking in- crease along the propagating direction of the main crack. KEY WORDS GH4169 superalloy;high temperature;crack propagation;grain boundary oxidation;8 phase 镍基高温合金由于在高温下具有优异的力学性 造).GH4169(国外牌号Inconel718)合金在航空 能和耐蚀性，被广泛应用于航空发动机涡轮盘的制 发动机历史上是使用最为广泛的镍基高温合金材 收稿日期：2017-06-28 基金项目：国家自然科学基金资助项目(51371023)工程科学学报,第 40 卷,第 7 期:822鄄鄄832,2018 年 7 月 Chinese Journal of Engineering, Vol. 40, No. 7: 822鄄鄄832, July 2018 DOI: 10. 13374 / j. issn2095鄄鄄9389. 2018. 07. 008; http: / / journals. ustb. edu. cn GH4169 合金高温疲劳裂纹扩展的微观损伤机制 侯 杰, 董建新苣 , 姚志浩 北京科技大学材料科学与工程学院,北京 100083 苣 通信作者, E鄄mail: jxdong@ ustb. edu. cn 摘 要 空气环境对高温合金在高温下的损伤行为有显著影响. 为了研究标准热处理态 GH4169 合金在高温疲劳裂纹扩展 过程中的微观损伤机制,在空气环境中进行 650 益 、初始应力强度因子幅 驻K = 30 MPa·m 1 / 2和应力比 R = 0郾 05 的低周疲劳裂纹 扩展试验. 使用扫描电镜(SEM)及能谱(EDS)对试样的断口、外表面和剖面进行观察和分析. 实验结果表明:疲劳主裂纹以 沿晶方式萌生并扩展,随后沿晶二次裂纹出现,并且其数量和长度沿主裂纹方向逐渐增加,进入快速扩展阶段后,断口呈现韧 窝组织形貌;在裂纹扩展过程中,啄 相与基体的界面发生氧化,使得沿晶二次裂纹沿界面扩展并产生偏折,从而起到阻碍二次 裂纹扩展的作用;试样外表面的主裂纹周围出现晶界氧化损伤区,其尺寸和晶界开裂程度沿主裂纹扩展方向逐渐增大. 关键词 GH4169 合金; 高温; 裂纹扩展; 晶界氧化; 啄 相 分类号 TG146郾 1 收稿日期: 2017鄄鄄06鄄鄄28 基金项目: 国家自然科学基金资助项目(51371023) Microscopic damage mechanisms during fatigue crack propagation at high temperature in GH4169 superalloy HOU Jie, DONG Jian鄄xin 苣 , YAO Zhi鄄hao School of Materials Science and Engineering, University of Science and Technology Beijing, Beijing 100083, China 苣 Corresponding author, E鄄mail: jxdong@ ustb. edu. cn ABSTRACT The air environment strongly influences the damage behaviors of superalloys at high temperatures. To investigate the mi鄄 croscopic damage mechanisms during high鄄temperature fatigue crack growth in standard heat鄄treated GH4169 superalloys, low鄄cycle鄄fa鄄 tigue crack growth tests were conducted at 650 益 with initial stress intensity factor 驻K = 30 MPa·m 1 / 2 and stress ratio R = 0郾 05 under the air environment. The fracture surface, outside surface, and central sectioned surface of the specimen were observed and analyzed u鄄 sing scanning electron microscopy (SEM) and energy鄄dispersive spectrometry (EDS). The results show that the main fatigue crack ini鄄 tiates and propagates intergranularly, followed by the appearance of intergranular secondary cracks, whose quantity and length increase along the propagating direction of the main crack. In the rupture stage, a dimpled morphology appears on the fracture surface. Oxida鄄 tion occurs at the interfaces between 啄 phases and the matrix during the fatigue crack propagation process, which leads to secondary cracks propagating along the interfaces. This leads to their inflection, which in turn retards their propagation. A grain鄄boundary oxida鄄 tion damage zone exists at the outside surface of the specimen near the main crack. The size and degree of grain鄄boundary cracking in鄄 crease along the propagating direction of the main crack. KEY WORDS GH4169 superalloy; high temperature; crack propagation; grain boundary oxidation; 啄 phase 镍基高温合金由于在高温下具有优异的力学性 能和耐蚀性,被广泛应用于航空发动机涡轮盘的制 造[1] . GH4169(国外牌号 Inconel 718) 合金在航空 发动机历史上是使用最为广泛的镍基高温合金材