The high-cycle fatigue (HCF) lives of nickel-based single crystal (N-SC) superalloys with different porosity sizes were investigated at $980°\text{C}$. The test results show that the failure cracks are prone to initiate from large pores, and the oxide layer can also act as initiation site for secondary cracks when under low stress level. Despite the observation of oxide layer, the pore defect size remains the dominant parameter controlling fatigue life. Therefore, a prediction model based on the critical plane was used to quantitatively evaluate the effect of pure porosity size on the HCF property of N-SC superalloys. The prediction results show that the proposed model is effective and applicable in engineering.

研究了不同孔隙度的镍基单晶（N-SC）高温合金的高循环疲劳（HCF）寿命。 $980°\text{C}$。测试结果表明，失效裂纹易于从大孔中萌生，并且在低应力水平下，氧化层还可以作为次级裂纹的萌生部位。尽管观察到氧化物层，但孔缺陷尺寸仍然是控制疲劳寿命的主要参数。因此，使用基于临界平面的预测模型来定量评估纯孔隙度对N-SC高温合金HCF性能的影响。预测结果表明，所提模型是有效的，可应用于工程。