Many high-temperature rotating components are always subjected to complex loading waveforms, arising the concerns for multi-damage driving crack initiation. In this paper, a series of strain-controlled low cycle fatigue (LCF) and creep-fatigue interaction (CFI) tests as well as the novel creep-fatigue combined with high-low cycle (CF-HL) tests were performed in a nickel-based superalloy at 650 ℃. Then, post-test microstructure observations were carried out to reveal the damage mechanisms under the multi-damaged CF-HL loading based on the EBSD-TEM combinative characterizations. In this aspect, the single-slip-dominated deformation mechanism under CFI loadings transformed to double-slip-dominated one under CF-HL loading was revealed. Computationally, a numerical procedure with a combination of crystal plasticity theory and finite element implementation was constructed for predicting the CF-HL crack initiation life and quantifying the crack initiation mechanisms. With the help of the developed fatigue and creep indicator parameters represented by accumulated energy dissipation, good agreements between experimental data and simulated results were achieved within a scatter band of ± 2 on life prediction. In addition, the simulation results indicate that the combined effects of grain orientation and multiple slip system activation showed great influence on the CF-HL crack initiation.

许多高温旋转部件总是受到复杂的加载波形，引起多损伤驱动裂纹萌生的担忧。在本文中，在镍合金中进行了一系列应变控制的低周疲劳 (LCF) 和蠕变疲劳相互作用 (CFI) 试验，以及新型蠕变疲劳结合高低周 (CF-HL) 试验。基高温合金在 650 ℃。然后，基于 EBSD-TEM 组合表征，进行了测试后微观结构观察，以揭示多损伤 CF-HL 载荷下的损伤机制。在这方面，揭示了CFI载荷下的单滑移为主的变形机制转变为CF-HL载荷下的双滑移为主的变形机制。计算上，构建了一个结合晶体塑性理论和有限元实现的数值程序，用于预测 CF-HL 裂纹萌生寿命和量化裂纹萌生机制。借助所开发的以累积能量耗散为代表的疲劳和蠕变指标参数，在寿命预测的±2散布带内，实验数据和模拟结果之间取得了良好的一致性。此外，模拟结果表明，晶粒取向和多滑移系激活的综合作用对CF-HL裂纹萌生有很大影响。借助所开发的以累积能量耗散为代表的疲劳和蠕变指标参数，在寿命预测的±2散布带内，实验数据和模拟结果之间取得了良好的一致性。此外，模拟结果表明，晶粒取向和多滑移系激活的综合作用对CF-HL裂纹萌生有很大影响。借助所开发的以累积能量耗散为代表的疲劳和蠕变指标参数，在寿命预测的±2散布带内，实验数据和模拟结果之间取得了良好的一致性。此外，模拟结果表明，晶粒取向和多滑移系激活的综合作用对CF-HL裂纹萌生有很大影响。