Microstructural influences on fatigue crack initiation and early propagation in Ni-based superalloy
Microstructural influences on fatigue crack initiation and early propagation in Ni-based superalloy
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DOI：
10.1080/02670836.2022.2070336
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发表时间：
2022-05-07
影响因子：
1.8
通讯作者：
Reed, Philippa
中科院分区：
文献类型：
--
作者：
Kim, Donghyuk;Jiang, Rong;Reed, Philippa
本文研究了RR 1000合金在室温下单峰二次γ尺寸和晶粒取向对疲劳裂纹萌生和早期裂纹扩展的影响。疲劳试验表明，裂纹主要是在滑移带和/或孔隙，然后由晶体学刻面形成，而更分散的应变局部化观察周围的孔隙由SEM-DIC分析。疲劳寿命与裂纹萌生和随后的裂纹合并（加速裂纹扩展）的数量有关。EBSD映射的滑动轨迹分析表明，裂纹可能沿着具有相对高的施密德因子的主活动滑动系统扩展。在这里进行的测试中，裂纹萌生事件的随机性比二次伽马尺寸的变化对总寿命有更多的控制。
Effects of unimodal secondary gamma' size and grain orientation on fatigue crack initiation and early crack propagation at room temperature have been investigated in RR1000 alloy. Fatigue tests show cracks mainly initiated at slip bands and/or pores followed by crystallographic facet formation while more diffuse strain localisation is observed around the pores by SEM-DIC analysis. Fatigue lifetime is linked to the number of crack initiations and consequent crack coalescence, which accelerates crack propagation. Slip trace analysis with EBSD mapping shows cracks are likely to propagate along the primary active slip system with a relatively high Schmid Factor. In the tests conducted here, the stochasticity of crack initiation events has more control on the overall lifetime than variations in secondary gamma' size.