The effects of heat treatment on the microstructure,tensile properties of the GH41 69 Ni-base superalloy and the effects of grain sizes on the behavior of fatigue crack growth were studied by optical microscopy, scanning electron microscopy,tensile and fatigue testers.The results show that the mechanical properties of the tested alloy were improved after solution treatment followed by double aging treatment.With the increase of the solution temperature,the grain sizes of the alloy increased the strength decreased and the fatigue life was prolonged. The stages of small crack took up about 80% of fatigue life.The effects of grain sizes on small fatigue crack growth were not obvious.However the long crack growth rate decreased with the increase of the grain size.%采用光学显微镜、扫描电镜、拉伸及疲劳试验机等研究了热处理对 GH4169镍基高温合金显微组织和力学性能的影响，重点研究了晶粒尺寸对其疲劳小裂纹扩展的影响。结果表明：采用固溶加双时效的热处理工艺能够提高试验合金的力学性能，随着固溶温度升高，合金中晶粒尺寸变大，强度下降，疲劳寿命延长；小裂纹阶段占疲劳寿命的80％，晶粒尺寸对疲劳小裂纹扩展速率的影响不明显，但随着晶粒尺寸增大，长裂纹的扩展速率下降。
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