The fatigue behavior and damage mechanisms of Inconel 718 are investigated and discussed under thermomechanical fatigue (TMF) and isothermal fatigue (IF) test conditions. The experimental results show that cyclic temperature accelerates fatigue degradation compared to isothermal equivalents, and the fatigue life under in-phase (IP) TMF mode is shorter than that under out-of-phase (OP) mode. The S-N data can be fitted by Coffin-Manson equation under LCF condition, and TMF lifetime can be predicted by the model based on hysteresis loop energy with a comprehensive consideration of mechanical and thermal strains.

中文翻译：

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Inconel 718高温合金的等温和热机械疲劳行为

在热机械疲劳（TMF）和等温疲劳（IF）测试条件下，研究和讨论了Inconel 718的疲劳行为和损伤机理。实验结果表明，与等温等效条件相比，循环温度加速了疲劳退化，同相（IP）TMF模式下的疲劳寿命短于异相（OP）模式下的疲劳寿命。SN数据可以在LCF条件下通过Coffin-Manson方程拟合，而TMF寿命可以通过基于磁滞回线能量并综合考虑了机械和热应变的模型来预测。