Isothermal and thermomechanical fatigue behavior of Inconel 718 superalloy

Deng, Wen Jun; Xu, Jinghao; Hu, Yi; Huang, Zaiwang; Jiang, Liang

doi:10.1016/j.msea.2018.11.052

Cited by 52 publications

(24 citation statements)

References 39 publications

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“…The plot in Figure shows the predictions from simulations and its foundation comes from the experimental data recorded the literature. [ 35 ] The plot in Figure 6b with the logarithmic x ‐axis exhibits an apparent shape of the typical SN curve, which indicates that the stored energy is a necessary and sufficient criterion for fatigue crack initiation. The number of cycles to fatigue crack nucleation is found to consistently increase with increasing SED.…”

Section: Resultsmentioning

confidence: 97%

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Fatigue Behavior of Additively Manufactured IN718 with Columnar Grains

Akram

Mushongera

2020

Adv Eng Mater

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Fatigue failure of polycrystalline materials is often dominated by crack initiation processes, which are strongly influenced by salient features existing in the microstructure. Herein, a crystal plasticity framework based on the finite element method is used to quantitatively assess the mechanistic drivers existing in columnar IN718 polycrystals for fatigue crack nucleation. To that end, microstructurally differing polycrystalline samples are subjected to strain‐controlled cyclic loading at ambient conditions to elucidate the microstructural mechanisms of fatigue damage. 2D grain structures obtained from the cellular automata (CA) simulations of the additive manufacturing of IN718 are utilized to construct representative 3D microstructures for use in computational analyses. A criterion related to the stored energy density (SED) is used to predict the scatter in fatigue crack nucleation life. This criterion presents a unique and consistent approach toward predicting fatigue crack initiation at the microstructural scale. It is demonstrated that SED is necessary and sufficient to drive crack nucleation in low cycle fatigue. The results show that grain boundaries are the preferred crack initiation sites.

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Section: Resultsmentioning

confidence: 97%

“…The estimation of SED from experimental data using Equation () was done based on the available stress–strain data at the half life. [ 35 ] The maximum stress ranges from 750 MPa to 965 MPa under the same strain amplitude of 0.8%. The estimated SED was determined as 8.18 J cm −3 .…”

Section: Resultsmentioning

confidence: 99%

Fatigue Behavior of Additively Manufactured IN718 with Columnar Grains

Akram

Mushongera

2020

Adv Eng Mater

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“…It was found that at the temperature between 700 and 800°C, dislocation shearing γ' precipitates by dislocation pairs and stacking faults at medium and high strain amplitudes and at the temperature between 900 and 950°C, dislocations by-passing γ' precipitates was the main deformation mode. Deng et al 28 investigated the fatigue behavior and damage mechanisms of Inconel 718 under TMF and isothermal LCF. It was found that the S-N data can be fitted by the Coffin-Manson equation under the LCF condition, and the model based on hysteresis loop energy can be predicted lifetime under TMF condition.…”

Section: Introductionmentioning

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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“…Numerous investigations on the elevated temperature LCF of the nickel-based superalloy were performed [2][3][4]. Recent studies showed that the thermomechanical fatigue (TMF) loads influenced the fatigue damage mechanisms significantly [5][6][7][8][9] and the TMF lifetime can be significantly shorter than the isothermal one [10]. The turbine parts suffer from thermomechanical fatigue damage caused by the varying loads and temperatures.…”

Section: Introductionmentioning

confidence: 99%

“…The induction heating has the advantage of the high heating rate as well as the high efficiency and is widely used in TMF testing [9,11,15,16]. Due to the skin effect of the induced current, however, the induction heating only heats the surfaces of the specimen, and the higher the induction frequency, the shallower the heating depth.…”

Section: Introductionmentioning

confidence: 99%

Thermal Gradient Mechanical Fatigue Assessment of a Nickel-Based Superalloy

Yuan

Sun

2019

MATEC Web Conf.

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Turbine components generally work under thermomechanical loading conditions with varying temperature and significant temperature gradients. In the present work, a radiation heating system was developed to simulate thermal gradient mechanical fatigue (TGMF) loads in turbines. The specimen is externally heated by radiation and internally cooled by compressed air. Experiments showed that the TGMF life of the nickel-based superalloy is significantly shorter than that of the thermomechanical and the isothermal fatigue, although the thermal stress amplitude related to the temperature gradient is small. It was confirmed that the conventional fatigue models generated seriously deviations and could not catch effects of thermal gradients. The modified TGMF model introduced a correction term of the temperature gradient effects and can describe the TGMF lifetime of Inconel 718 reasonably. The new model provides a uniform description of isothermal and complex thermomechanical fatigue.

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Isothermal and thermomechanical fatigue behavior of Inconel 718 superalloy

Cited by 52 publications

References 39 publications

Fatigue Behavior of Additively Manufactured IN718 with Columnar Grains

Fatigue Behavior of Additively Manufactured IN718 with Columnar Grains

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

Thermal Gradient Mechanical Fatigue Assessment of a Nickel-Based Superalloy

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