High temperature fatigue crack growth in Inconel 718

Antunes, Filipe E.; Ferreira, José Manuel Martins; Branco, C.M.; Byme, J.

doi:10.1179/mht.2000.058

Cited by 21 publications

(12 citation statements)

References 17 publications

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“…[1, 2,[5][6][7][8][9][10][11][12][13][14], which all show that hold times at high temperature can have a devastating effect on the crack growth rate. The modelling of hold time effects has also been studied by a number of different authors, often by use of additive models based on Paris law [15,16] with a cyclic part, based on pure cyclic crack growth, and a time dependent part, based on pure time dependent crack growth, see e.g.…”

mentioning

confidence: 99%

A load history dependent model for fatigue crack propagation in Inconel 718 under hold time conditions

Lundström

Simonsson

Gustafsson

et al. 2014

Engineering Fracture Mechanics

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Modelling of high temperature fatigue crack growth in Inconel 718 under the interaction of fast cyclic loading and hold times at maximum load has been conducted. A model, based on the concept of a damaged zone in front of the crack tip has been applied for three different temperatures, 550, 600 and 650• C, with good agreement for both calibration and validation tests. A statistical evaluation of 22 tests in total was also conducted, which shows that the developed model gives a reasonable scatter factor at a probability of failure of 0.1 %.

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mentioning

confidence: 99%

A load history dependent model for fatigue crack propagation in Inconel 718 under hold time conditions

Lundström

Simonsson

Gustafsson

et al. 2014

Engineering Fracture Mechanics

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“…The experimental data, propagation parameters and critical stress intensity factors were obtained from previous tests 14,15,20,21 . For turbine discs, the load wave can be approximated as trapezoidal with a minimum value of stress at zero.…”

Section: Life Prediction Results For the Test Discmentioning

confidence: 99%

Fatigue life prediction and failure analysis of a gas turbine disc using the finite‐element method

Cláudio

Branco²,

Gomes³

et al. 2004

Fatigue Fract Eng Mat Struct

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A B S T R A C T A numerical prediction of the life of a gas turbine model disc by means of the finite-elementtechnique is presented and the solution is compared with an experimental rim-spinning test. The finite-element method was used to obtain the K solution for a disc with two types of cracks, both at the notch root of the blade insert and located in the corner and in the centre. A crack aspect ratio of (a/c) = 1 was assumed. The fracture mechanics parameters J-integral and K were used in the assessment, which were computed with linear elastic and elastic-plastic material behaviour. Using a crack propagation program with appropriate fatigue-creep crack growth-rate data, previously obtained in specimens for the nickel-based superalloy IN718 at 600 • C, fatigue life predictions were made. The predicted life results were checked against experimental data obtained in real model discs.The numerical method, based on experimental fatigue data obtained in small laboratory specimens, shows great potential for development, and may be able to reduce the enormous costs involved in the testing of model and full-size components. a = crack depth c = half crack length at surface C, m = Paris law parameters E = Young's modulus f = frequency J = J-integral K = stress intensity factor K C = critical stress intensity factor N = number of cycles N t = total number of cycles N p = number of cycles in propagation N i = number of cycles in initiation R = radius r 2 = regression correlation coefficient S UTS = True ultimate tensile stress α = Thermal expansion coefficient K th = Threshold stress intensity factor Correspondence: R.A. Cláudio.

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“…In principle, the course of the crack growth rate vs. the test frequency for IN718 at 650 °C can be subdivided into three ranges. 20,21 At high frequencies, the propagation rate is controlled by cyclic deformation (cycle-dependent range) and a transgranular type of damage evolution can be expected. In the low frequency regime, the behaviour is time-dependent and the dynamic embrittlement leads to accelerated crack growth in combination with intergranular crack propagation.…”

Section: Introductionmentioning

confidence: 99%

“…These contributions are in the simple case linearly combined ignoring the mutual interactions of the damage mechanisms. 28 Alternatively, exclusively the term is considered which results in the fastest crack propagation, 21 or the different terms are weighted by individual weighting factors. [29][30][31] In the investigation presented, the dynamic embrittlement of the Ni-base superalloy IN718 was studied by putting the focus on the development of a detailed understanding of the mechanisms controlling the dynamic embrittlement process.…”

Section: Introductionmentioning

confidence: 99%

Effect of dynamic embrittlement on high temperature fatigue crack propagation in IN718 – experimental characterisation and mechanism-based modelling

Christ

Wackermann

Krupp

2016

Materials at High Temperatures

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At elevated temperatures, the nickel-base superalloy IN718 is prone to the failure type 'dynamic embrittlement'. Dynamic embrittlement is assumed to be driven by tensile stress-controlled oxygen grain boundary diffusion. Oxygen embrittles the grain boundaries in front of a crack and results in a fast brittle intercrystalline crack propagation. In order to reveal the mechanism of dynamic embrittlement, high temperature fatigue crack propagation tests were carried out at 650 °C in vacuum and air applying various dwell times and testing frequencies. The crack growth was monitored by the ACPD technique and a far-field microscope. The observations show that at low stress intensity factor ranges, crack propagation mainly occurs in the unloading and loading parts of the cycle and only minor crack propagation takes place during the dwell time. With increasing dwell time, the contribution of the crack propagation at constant stress increases. A mechanism-based model was developed on the basis of these findings which allows for a quantitative description of the effect of dynamic embrittlement on fatigue crack propagation rate. The results of respective simulations correspond very satisfactorily to the experimental data. Hence, the model is suitable for lifetime assessment.

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High temperature fatigue crack growth in Inconel 718

Cited by 21 publications

References 17 publications

A load history dependent model for fatigue crack propagation in Inconel 718 under hold time conditions

A load history dependent model for fatigue crack propagation in Inconel 718 under hold time conditions

Fatigue life prediction and failure analysis of a gas turbine disc using the finite‐element method

Effect of dynamic embrittlement on high temperature fatigue crack propagation in IN718 – experimental characterisation and mechanism-based modelling

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