In this study, cyclic deformation behaviors of nickel-based GH4169 superalloy are investigated in both experimental and simulated aspects via cyclic loading waveforms (i.e., PP, CP, PC and CC) at 650℃. Cyclic softening, stress relaxation and damage evolutions are analyzed, in which asymmetric cyclic softening in both peak/valley directions are demonstrated. The analysis of internal stress evolutions indicates that back stress is dominant and isotropic stress is secondary in cyclic softening. Afterward, a modified damage-coupled viscoplastic constitutive model is established to describe the complex cyclic behaviors as well as the damage evolutions. A term related to the first invariant of stress is incorporated into isotropic hardening rule and a softening factor introduced into the Ohno-Wang kinematic hardening rule. Additionally, a damage variable related to Young’s modulus is coupled into the model, which is experimentally validated via life prediction for more abundant experimental data points. The modified model is expected to provide an in-depth insight into cyclic behaviors and fatigue life under wide loading waveforms for industrial applications.

本研究通过循环载荷波形（即PP、CP、PC和CC）在650℃下从实验和模拟两个方面研究镍基GH4169高温合金的循环变形行为。分析了循环软化、应力松弛和损伤演化，其中证明了峰/谷方向的不对称循环软化。内应力演化分析表明，在循环软化过程中，背应力占主导地位，各向同性应力占次要地位。然后，建立了一个修正的损伤耦合粘塑性本构模型来描述复杂的循环行为以及损伤演化。与应力的第一不变量相关的术语被纳入各向同性硬化中规则和软化因子引入到 Ohno-Wang 运动硬化规则中。此外，将与杨氏模量相关的损伤变量耦合到模型中，通过寿命预测进行实验验证，以获得更丰富的实验数据点。修改后的模型有望深入了解工业应用在宽负载波形下的循环行为和疲劳寿命。