ABSTRACT In this study, thermomechanical fatigue (TMF) behaviours, failure mechanisms and the lifetime prediction method of a nickel-based single-crystal superalloy with [001] orientation were investigated based on the stress-controlled TMF experiments at different stress/temperature ranges, dwell times and phase angles. The fractographic observations revealed a creep-fatigue failure mechanism for in-phase thermomechanical fatigue (IP TMF) and an oxidation-fatigue failure mechanism for out-of-phase thermomechanical fatigue (OP TMF). According to the observed physical phenomenon of the slip along particular planes during the deformation process, selecting the steady-ratcheting shear-strain rate as the representative physical quantity, a new critical-plane-based lifetime prediction model which was suitable for a variety of experiment conditions was established. The predicted lifetimes for both standard specimens and turbine blades showed good agreements with the experimental data. The strong versatility and the concise mathematic form that made the model have some practical application value.

中文翻译：

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基于临界面的热机械疲劳寿命预测模型及其在镍基单晶涡轮叶片中的应用

摘要 在本研究中，基于不同应力/温度范围的应力控制 TMF 实验，研究了具有 [001] 取向的镍基单晶高温合金的热机械疲劳 (TMF) 行为、失效机制和寿命预测方法，驻留时间和相位角。断口观察揭示了同相热机械疲劳 (IP TMF) 的蠕变疲劳失效机制和异相热机械疲劳 (OP TMF) 的氧化疲劳失效机制。根据观察到的变形过程中沿特定平面滑移的物理现象，选取稳态棘轮剪应变率作为代表物理量，建立了适用于多种实验条件的新的基于临界平面的寿命预测模型。标准试样和涡轮叶片的预测寿命与实验数据吻合良好。强大的通用性和简洁的数学形式使该模型具有一定的实际应用价值。