Microporosity is one of the most common defects in nickel base single crystal (N-SC) superalloys, which is a great threat to fatigue performance. In this paper, nine porosity-related fatigue damage parameters for N-SC superalloys were selected by referring to those parameters originally proposed for casting and 3D printing metal materials as well as the critical plane damage parameters commonly used in N-SC superalloys. According to the plastic constitutive model of single crystals, a crystal plastic finite element (CPFE) model was established to evaluate these different fatigue damage parameters, and the parameters of CPFE were calibrated by the low cycle fatigue (LCF) hysteresis loop obtained from the fatigue test. The evaluation results showed that the geometric mean of stress–strain concentration factor (GCF) $k_g$ was a satisfactory parameter to quantify the effect of porosity defects on fatigue. Inspired by the discovery and considering the slip systems characteristics of N-SC superalloys, the geometric mean of resolved stress–strain concentration factor (GRCF) $k_{\mathit{rg}}$ on slip systems was proposed, and it was found that the $max(k_{\mathit{rg}},k_g)$ could be used to predict the fracture modes of N-SC superalloys. Based on the $max(k_{\mathit{rg}},k_g)$, a porosity-related fatigue life prediction method which can distinguish the fracture modes was put forward. The prediction results showed that the fracture mode prediction results were consistent with the test results, and the life prediction results were also improved compared with the GCF parameter.

微孔性是镍基单晶（N-SC）高温合金中最常见的缺陷之一，它对疲劳性能具有很大的威胁。本文通过参考最初建议用于铸造和3D打印金属材料的参数以及N-SC超级合金常用的临界平面损伤参数，选择了N-SC超级合金的9个与孔隙率相关的疲劳损伤参数。根据单晶的塑性本构模型，建立了结晶塑性有限元（CPFE）模型来评估这些不同的疲劳损伤参数，并通过从疲劳获得的低周疲劳（LCF）磁滞回线对CPFE的参数进行了校准。测试。评价结果表明，应力-应变集中系数（GCF）的几何平均值${ķ}_G$是量化孔隙缺陷对疲劳影响的令人满意的参数。受发现的启发并考虑了N-SC超级合金的滑移系统特性，解析应力-应变集中系数（GRCF）的几何平均值${ķ}_{\mathit{g}}$ 在滑移系统上提出了建议，结果发现 $最高（{ķ}_{\mathit{g}}，{ķ}_G）$可用于预测N-SC高温合金的断裂模式。基于$最高（{ķ}_{\mathit{g}}，{ķ}_G）$提出了一种可以区分断裂模式的孔隙率相关的疲劳寿命预测方法。预测结果表明，与GCF参数相比，断裂模式预测结果与试验结果一致，寿命预测结果也有所改善。