The effect of cyclic loading on the creep fatigue life and creep strength of a DS superalloy: Damage mechanism and life modeling

Fatigue Fract Eng Mat Struct

Han

et al. 2020

Considering the flexible operation conditions, the creep‐fatigue performance of P92 steel plays a crucial role in manufacturing structural components of ultra‐supercritical fossil power plants at 620°C–630°C. The creep‐fatigue interaction tests of P92 steel were conducted at 630°C in air with different duration periods, where the duration periods were simultaneously added on the peak tensile strain and valley compressive strain. The addition of hold time resulted in a rapid decrease of fatigue life, where the reduction amplitude increasing with the hold time. There was more than five times reduction as the hold time increased to 300 s. Moreover, the stress relaxation behavior during hold time exhibited a saturation behavior at long dwell time, where the limited relaxed stress gradually approached to the creep threshold stress. Furthermore, a modified strain energy density exhaustion model involving creep threshold stress was proposed and provided more accurate predictions in comparison with the conventional model, reducing the conservatism.

Section: Introductionmentioning

confidence: 99%

Analysis on stress‐strain behavior and life prediction of P92 steel under creep‐fatigue interaction conditions

Fatigue Fract Eng Mat Struct

Han

et al. 2020

“…HTHC fatigue/creep-fatigue experiments in Zhao et al 40 were performed at a frequency of 0.5 Hz, and in Li et al 41 at a constant stress rate of 400 MPa s À1 . The specific experimental process and data are presented in Zhao et al, 40 Li et al, 41 Hu et al, 42 and Huang et al 43 Similarly, the oxidation fatigue/creep-fatigue experimental results at 980 C are shown in Figure 3 from Hu et al 42 and Huang et al 43 HTHC fatigue/creep-fatigue experiments were conducted at 850 C for tensile hold times of 0, 1, 60, 120, and 240 s. The test results are shown in Figure 4 from Zhao et al 40 and Li et al 41…”

Section: Creep-fatigue Testing Results At Elevated Temperaturesmentioning

confidence: 99%

Damage evolution and life modeling of hot corrosion environment on creep‐fatigue of a directionally solidified nickel‐based superalloy

Fatigue Fract Eng Mat Struct

et al. 2023

This study developed a corrosion‐creep fatigue‐life‐prediction methodology based on continuous‐damage mechanics (CDM). A systematic investigation of the turbine‐blade material DZ125 (a nickel‐based superalloy) was conducted, including oxidation and high‐temperature hot corrosion‐creep fatigue tests. Pre‐exposure experiments explained the damage process in DZ125. The applicability of the CDM‐based life‐prediction model of DZ125 was verified experimentally and by comparison with corresponding data from published studies. The model exhibited excellent life‐prediction ability for gas‐turbine hot‐section components vulnerable to cyclic loads and hot corrosion combined.

“…However, research on the cyclic creep response of a nickel-based super alloy, DZ125, under different gradients of stress amplitudes and temperatures showed that cyclic creep accelerated the strain accumulation rate compared to static creep. The fatigue rate without a peak stress hold was reported to be the upper rate of the cyclic creep [14]. Other cases where fatigue damage dominated could be found on pure metal copper [15] and AMg6 alloy [16].…”

Section: Introductionmentioning

confidence: 98%

Cyclic Creep Behavior and Modified Life Prediction of Bainite 2.25Cr-1Mo Steel at 455 °C

Jiang

Ogunmola

et al. 2020

Metals

Uniaxial static and cyclic creep tests were carried out on bainite 2.25Cr-1Mo steel at 455 °C. Effects of the unloading rate from 0.6 to 39 MPa/s and valley stress duration from 0 to 30 min on the cyclic creep deformation behavior were discussed. The results indicated that the fracture behavior under static and cyclic creep conditions showed a consistent ductile mode. The strain accumulation rate under cyclic creep was significantly retarded as compared with static creep due to the presence of anelastic recovery which was apparently influenced by the unloading conditions. For cyclic creep tests, the unrecoverable strain component determined by a systematic classification of the stress–strain curve was the true damage. A modified life prediction method proposed based on the unrecoverable strain component presented a good life prediction for cyclic creep.