Deformation mechanisms of a nickel-based single-crystal superalloy during low-cycle fatigue at different temperatures

Wang, X.G.; Liu, J.L.; Jin, Tao; Sun, Xiaofeng; Zhou, Yu; Hu, Z.Q.; Do, Jeonghyeon; Choi, Baig-Gyu; Kim, I.S.; Jo, Chang-Yong

doi:10.1016/j.scriptamat.2014.11.026

Cited by 53 publications

(6 citation statements)

References 20 publications

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“…Therefore, the DDP calculations predict higher climb rates and increased cyclic softening in the h = 0.5 µm composite compared to the h = 1 µm composite. We emphasise that the dislocation cell structures predicted by the DDP calculations are consistent with a wide body of observations [4,21,22,23] reported for high-temperature LCF of nickel-based superalloys.…”

Section: Resultssupporting

confidence: 87%

Discrete dislocation plasticity analysis of the high-temperature cyclic response of composites

Shishvan

McMeeking

Pollock

et al. 2018

Materials Science and Engineering: A

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Discrete dislocation plasticity (DDP) analysis of the high-temperature cyclic deformation of twophase composites comprising a plastic matrix and elastic precipitates is presented. Deformation of the matrix is by climb-assisted glide of dislocations while the precipitates deform by a combination of bulk elasticity and stress-driven interfacial diffusion. The DDP calculations predict a cyclically softening response due to the formation of dislocation cell structures within the matrix. The dislocation cell sizes decrease with decreasing size of the unit cell (or equivalently matrix channels) and this results in an increased cyclic softening rate in composites with smaller unit cells. Interfacial diffusion also enhances the formation of dislocation cell structures and thereby promotes cyclic softening. These results are consistent with predictions of the creep behaviour that indicate that the increase in the creep rate (i.e. tertiary creep) is also associated with the formation of dislocation cell structures within the matrix.

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Section: Resultssupporting

confidence: 87%

Discrete dislocation plasticity analysis of the high-temperature cyclic response of composites

Shishvan

McMeeking

Pollock

et al. 2018

Materials Science and Engineering: A

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“…And the SFs significantly affect mechanical behaviors. However, during the LCF at 760 °C, the SFs just appeared in the γ phase, whereas few was present in the γ' phase [27].…”

Section: Introductionmentioning

confidence: 95%

Low-Cycle Fatigue and Creep-Fatigue Behaviors of a Second-Generation Nickel-Based Single-Crystal Superalloy at 760 °C

Zhang

Guo

Yang

et al. 2020

Acta Metall. Sin. (Engl. Lett.)

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Low-cycle fatigue (LCF) behaviors of a second-generation nickel-based single-crystal superalloys with [001] orientation at 760 °C have been investigated. Different strain amplitudes were introduced to investigate the creep-fatigue effects. The LCF life of none tensile holding (NTH) was higher than that of the 60-s tensile hold (TH) at any strain amplitude. As the strain amplitude was 0.7%, the stacking and cross-slip dislocations appeared together at the γ/γ' coherent microstructure in both TH and NTH specimens. At the strain amplitude of 0.9%, plenty of the cross-slip dislocations appeared in γ channel and other dislocations were stacking at γ/γ' interfaces. However, the SFs still appeared in γ' phase with 60-s TH which caused cyclic softening. As the strain amplitude increased up to 1.2%, the dislocations are piling up at the γ/γ' interfaces and cutting through the γ' phase in both TH and NTH tests, which caused cyclic hardening. The influences of strain amplitude and holding time were complicated. Different stress response behaviors occurred in different loading conditions. The surface characteristic and fracture mechanism were observed by scanning electron microscopy. This result is helpful for building the relationship of various blade fatigue failure modes, cyclic stress response and microstructure deformation under different strain amplitudes.

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“…6, for LCF tests, reveals that the fatigue life is decreased when the temperature shifts from 600°C to 800°C for all strain amplitudes. The occurrence of the cyclic softening behavior in precipitation-hardened alloys depends on some reasons which are the formation of dislocation networks at the γ/γ' interface, shearing of precipitates, dissolution of precipitates, and coarsening of the precipitates 11,46,47 . The cyclic stress-strain hysteresis loops obtained with the experimental test data for two temperature conditions indicated that, at a lower temperature, the material had higher stiffness when the load was aligned along the solidification direction of the material.…”

Section: Resultsmentioning

confidence: 99%

Low cycle fatigue behavior and fracture mechanism of a directionally solidified CM247 LC superalloy

Salehnasab

poursaeidi

2020

Preprint

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In gas turbines, superalloys are exposed to thermal as well as mechanical cyclic loadings during start-up and shut down processes, which can accelerate the formation of fatigue failure mechanisms. In the present study, low cycle fatigue behavior and fracture mechanism of a directionally-solidified CM247 LC superalloy at two temperatures of 600°C and 800°C were investigated. For this purpose, strain-controlled low cycle fatigue tests were carried out at 600°C and 800°C, and constant total strain amplitudes of 0.4, 0.6, 0.8, and 1% were applied during the totally reversed loading ratio (R = -1). The Coffin-Manson model, based on plastic deformation and a model based on the hysteresis energy criterion is used to predict fatigue life and evaluate the low cycle fatigue behavior. SEM observations of the surface of the failed specimen showed similar LCF failure mechanisms in all the strain amplitudes and temperatures.

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Deformation mechanisms of a nickel-based single-crystal superalloy during low-cycle fatigue at different temperatures

Cited by 53 publications

References 20 publications

Discrete dislocation plasticity analysis of the high-temperature cyclic response of composites

Discrete dislocation plasticity analysis of the high-temperature cyclic response of composites

Low-Cycle Fatigue and Creep-Fatigue Behaviors of a Second-Generation Nickel-Based Single-Crystal Superalloy at 760 °C

Low cycle fatigue behavior and fracture mechanism of a directionally solidified CM247 LC superalloy

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