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在晶体塑性理论的基础上,提出了一种适用于镍基单晶高温合金热机械疲劳的本构模型,并采用该模型对单晶材料不同晶体取向的热机械疲劳力学响应进行有限元模拟。结果表明,该本构模型可以较好地模拟镍基单晶合金的热机械疲劳行为。对于同相位热机械疲劳,压缩应力幅大于拉伸应力幅,循环平均应力小于零;对于反相位热机械疲劳,拉伸应力幅大于压缩应力幅,循环平均应力大于零。随着循环次数的增加,材料呈现出在高温半周为初始软化,低温半周为初始硬化的特征。晶体取向对于材料的热机械疲劳性能具有显著的影响。
Based on the crystal plasticity theory, a constitutive model suitable for thermo-mechanical fatigue of Ni-based single crystal superalloy was proposed and used to simulate the thermo-mechanical fatigue response of different crystal orientations of single crystal materials. The results show that this constitutive model can simulate the thermo-mechanical fatigue behavior of Ni-based single crystal alloys. For the same phase of thermo-mechanical fatigue, the compressive stress amplitude is greater than the tensile stress amplitude, the average cyclic stress is less than zero; for the anti-phase thermal mechanical fatigue, the tensile stress amplitude is greater than the compressive stress amplitude, the average cyclic stress is greater than zero. With the increase of the number of cycles, the material showed the initial softening at high temperature for half a week and the initial half-cycle at low temperature. The crystal orientation has a significant effect on the thermo-mechanical fatigue properties of the material.