在室温下使用超声疲劳试验机对GH4169镍基高温合金进行了105~108周次的疲劳试验,获得了S-N曲线并观察了疲劳断口形貌.结果表明:S-N曲线呈逐渐下降的趋势,没有出现疲劳极限,在超过107周次的循环后试样仍发生疲劳破坏;疲劳裂纹的萌生位置并未随S-N曲线的下降呈现出规律性,裂纹主要萌生于试样表面,少量萌生于试样内部;在超声疲劳载荷作用下试样同时存在塑性和脆性两种破坏方式.
The fatigue tests in 105-108 cycles of GH4169 Ni-based superalloy were carried out at ambient temperature by the ultrasonic fatigue tester, and then the S-N curve was obtained and the fatigue fracture morphology was observed.The results show that the S-N curve exhibited a descending trend and the fatigue limit was not observed.The fatigue fracture of the specimen still occurred when the number of cycles exceeded 107 .The fatigue crack initiation positions didn′t show the regularity with the S-N curve descending.The fatigue cracks mostly initiated from the surface and few from internal of the specimen.Under the ultrasonic load the plastic and brittle failure modes were both found in the specimen.
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