The creep-fatigue behavior of a nickel-based superalloy: Experiments study and cyclic plastic analysis

• Published in: International journal of fatigue 2021-06, Vol.147, p.106187, Article 106187
• Main Authors: Sun, Li, Bao, Xiao-Guang, Guo, Su-Juan, Wang, Run-Zi, Zhang, Xian-Cheng, Tu, Shan-Tung
• Format: Article
• Language: English
• Subjects: Back stress; Creep-fatigue; Cyclic softening; Isotropic stress; Stress relaxation
• ISSN: 0142-1123; 1879-3452
• DOI: 10.1016/j.ijfatigue.2021.106187

•Creep-fatigue tests for GH4169 under symmetric and asymmetric strain cyclic loadings.•Comprehensive study on the cyclic plastic evolution and creep-fatigue life of GH4169.•GH4169 shows tension–compression asymmetry and more obvious tensile cyclic softening.•Mean stress relaxes under asymmetric and symmetric loading with valley strain dwells.•Cyclic softening dominated by back stress evolution and accelerated by strain dwells. Cyclic behavior of a nickel-based GH4169 superalloy under fully-reversed and asymmetric creep-fatigue tests with strain-controlled is investigated at 650℃. Significant tension–compression asymmetry and continuous cyclic softening are observed for all loading waveforms. The material exhibits mean stress relaxation under asymmetric loading and fully-reversed loading with valley strain dwells. Moreover, stress relaxation behavior during the dwell period is almost independent of the number of cycles. In order to identify the deformation mechanism, the evolutions of mean value and amplitude of the internal stress (back stress and effective stress) based on the partition of hysteresis loops are analyzed. Results show that both the cyclic softening and mean stress relaxation are primarily dominated by the evolution of back stress and secondarily affected by that of effective stress. Such findings lay a solid foundation for further investigations of reasonable cyclic deformation description and accurate life prediction in GH4169 alloy under creep-fatigue loadings.