(1. 中国科学院 金属研究所，沈阳 110016；
2. 钢铁研究总院 高温材料研究所，北京 100081)
摘 要: 对GH4698合金在室温、650及750 ℃的裂纹扩展行为进行研究，讨论温度对裂纹扩展寿命与速率的影响，观察不同温度下的裂纹扩展断口。采用背散射电子衍射(EBSD)技术对合金裂纹扩展的晶体学机制进行分析。结果表明，随着温度的升高，合金的裂纹扩展寿命降低，裂纹扩展速率增加，断裂模式由室温下穿晶断裂为主转变为高温下的沿晶断裂为主；裂纹附近应变程度较大，且小角度晶界密度较高。
关键字: 镍基高温合金；疲劳裂纹扩展；疲劳机制
（1. Institute of Metal Research, Chinese Academy of Sciences, Shenyang 110016, China;
2. High Temperature Materials Research Institute, Central Iron and Steel Research Institute, Beijing 100081, China）
Abstract:The crack propagation behavior of GH4698 alloy was studied respectively at room temperature, 650 and 750 ℃. The effects of temperature on the crack propagation rate were discussed, the fractures under different temperatures were observed and the electron back scattering diffraction (EBSD) technique was applied to investigate the mechanism of crack propagation. The results show that with the increase of temperature, the fatigue life of the alloy reduces and crack propagation rate increases, and the main propagation mode of cracks changes from transgranular to intergranular. The grains near cracks have relative high deformation degree and high density, small angle grain boundaries.
Key words: Ni-based superalloy; fatigue crack propagation; fatigue mechanism
