Fatigue Crack Growth in Nickel‐based Superalloys at 500‐700°c. I: Waspaloy

Lynch, S.P.; Radtke, T. C.; Wicks, B. J.; Byrnes, R.T.

doi:10.1111/j.1460-2695.1994.tb00231.x

Cited by 37 publications

(8 citation statements)

References 20 publications

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“…Another possible influencing factor is a larger COD under plain strain conditions in the bulk, which could facilitate the access of oxygen to the crack tip. This suggestion was made by Lynch et al 15 . to explain the thicker oxide films obtained with trapezoidal waveforms when compared with sinusoidal wave shapes.…”

Section: Discussionmentioning

confidence: 83%

Influence of stress state on high temperature fatigue crack growth in Inconel 718

Antunes

Ferreira

Branco

et al. 2001

Fatigue Fract Eng Mat Struct

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The influence of stress state on fatigue crack growth in nickel‐base superalloys at high temperature is considered, based on studies in corner crack specimens of Inconel 718 at 600 °C. At high frequency and low R, cycle‐dependent trans‐granular crack growth occurs along the whole crack front, and growth rates are similar at the surface and within the interior of specimens, maintaining the original quarter‐circular shape. For conditions of low frequency and high R, increased crack growth rate per cycle is observed with the crack tunnelling ahead at the centre. A time‐dependent intergranular crack propagation mode occurs in the plane strain interior, attributed to an oxidation mechanism, whereas near the surfaces under plane stress, a trans‐granular cyclic plasticity mechanism is observed. It is proposed that in addition to frequency and R, that stress state influences the competition between the mechanisms controlling crack growth and the transition between them: plane strain in the interior favouring an oxidation‐controlled intergranular cracking mechanism as compared with the plane stress surfaces where cyclic plasticity dominates. An FEM study suggests that this influence of stress state is not associated with variation of ΔK along the crack front.

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Section: Discussionmentioning

confidence: 83%

Influence of stress state on high temperature fatigue crack growth in Inconel 718

Antunes

Ferreira

Branco

et al. 2001

Fatigue Fract Eng Mat Struct

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“…It is well known that the environment can significantly affect the fatigue crack propagation rate (see, e.g. Refs [33, 34]). In order to investigate this effect, similar experiments are performed as those described in chapter 2.…”

Section: The Effect Of Environmentmentioning

confidence: 99%

On the mechanism of fatigue crack propagation in ductile metallic materials

Pippan

Zelger

Gach

et al. 2010

Fatigue &Amp; Fracture of Engineering Materials &Amp; Structures

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A B S T R A C T An overview of our research performed during the last 15 years is presented to improve the understanding of fatigue crack propagation mechanisms. The focus is devoted to ductile metals and the material separation process at low and intermedial crack propagation rates. The effect of environment, short cracks, small-scale yielding as well as large-scale yielding are considered. It will be shown that the dominant intrinsic propagation mechanism in ductile metallic materials is the formation of new surface due to blunting and the resharpening during unloading. This process is affected by the environment, however, not by the length of the crack and it is independent of large-or small-scale yielding.a = crack length c = Manson-Coffin exponent CTOD = crack tip opening displacement da/dN = fatigue crack propagation rate K max , K min = maximum and minimum stress intensity factor N f = number of cycles to failure R = stress ratio K min /K max CTOD = cyclic crack tip opening displacement ε pl = plastic strain range J = cyclic J-integral J eff = effective cyclic J-integral K = stress intensity rang W e = elastic component of the remote strain energy density range W p = plastic component of the remote strain energy density range σ y = yield stress Figure 1 shows the fatigue crack propagation behaviour of austenitic steel. Such fatigue crack propagation rate, da/dN , versus stress intensity range, K, curves are typical for ductile metals. The fatigue crack propagation behaviour of such materials is characterized by: a steep drop of the crack propagation rate at the threshold of stress intensity range, K th , an extended Paris regime with a Correspondence: R. Pippan. I N T R O D U C T I O N

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“…This is particularly relevant in the mixed time/cycle‐dependent regime where micromechanisms may include oxidation and fatigue–creep interaction at intermediate temperatures. The effect of cyclic frequency on crack growth behaviour at elevated temperature has been the subject of many researches 2 –11 . The existence of cycle‐, time‐ and mixed time/cycle‐dependent behaviour in frequency domain was first noted by Solomon 3 who composed what was described as a mechanism map for an iron‐based superalloy A286.…”

Section: Introductionmentioning

confidence: 99%

“…Extensive research has been carried out on Inconel 718 2 , 4 , 6 for which mechanism maps are available 2 . Effects of frequency on crack growth behaviour have also been studied in some nickel‐based alloys, including AP1, 7 Rene’95 8 and Waspaloy, 9 –11 although few attempts have been made to generate complete mechanism maps, possibly due to the limitations of the experimental methods adopted. In general, the change in crack growth rate reflects the characteristics of the material for a given testing condition.…”

Section: Introductionmentioning

confidence: 99%

Effects of frequency on fatigue crack growth at elevated temperature

Tong

Byrne

1999

Fatigue Fract Eng Mat Struct

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The effects of frequency on fatigue crack growth behaviour have been studied in a prealloyed powder material, Udimet 720Li, at 650 °C. Fracture mode and fatigue crack growth behaviour were studied at frequencies ranging from 0.001 to 5 Hz using a balanced triangular waveform. Tests were carried out under constant ΔK control, with load ratio and temperature being held constant. A mechanism map was constructed where predominantly time, mixed and cycle‐dependent crack growth behaviour were identified. The results were verified by SEM analyses. Cycle‐dependent crack growth data were obtained at room temperature, while fully time‐dependent crack growth data were generated under sustained loads at 650 °C. It was found that mixed time/cycle‐dependent behaviour is of most significance for this material at the temperature and frequencies studied. Data for other nickel‐based superalloys from various sources in the literature were compiled and compared with those of U720Li alloy at a given stress intensity and temperature in the mixed regime. An analysis was developed to rationalize the observed effect of frequency on fatigue crack growth rate.

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Fatigue Crack Growth in Nickel‐based Superalloys at 500‐700°c. I: Waspaloy

Cited by 37 publications

References 20 publications

Influence of stress state on high temperature fatigue crack growth in Inconel 718

Influence of stress state on high temperature fatigue crack growth in Inconel 718

On the mechanism of fatigue crack propagation in ductile metallic materials

Effects of frequency on fatigue crack growth at elevated temperature

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