The Influence of Microstructure upon the Creep and Fatigue Crack Growth Behaviour in Inconel 718

Thamburaj, Robinson; Koul, A. K.; Wallace, W.E.; Terada, T.; Malherbe, Magali

doi:10.1007/978-94-009-5085-6_21

Cited by 6 publications

(10 citation statements)

References 10 publications

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“…In the presence of more homogeneous slip, the number of dislocations arriving at a grain boundary would be reduced and, consequently, the stress concentrations and 0 transport to the grain boundaries occurring due to a dislocation "sweep-in" mechanism will also be reduced. Examining thin foils prepared from regions immediately below fracture surfaces by means of transmission electron microscopy Thamburaj et al [42] observed that planar deformation was predominant in the case of existing the finest y " particle size distributions, and the poor resistance of fatigue crack growth in this case is consistent with the mechanism discussed above.…”

Section: Effect Of Grain Size and Grain Boundary Morphologysupporting

confidence: 62%

“…Grain boundary morphology is another important microstructural factor that controls the high-temperature crack growth behaviour. Thamburaj et al [42] have pointed out that an irregular grain boundary morphology developed by grain boundary 6 -phase precipitates will enhance creep ductility and resistance to high-temperature fatigue crack growth rate. Andrieu et al [46] observed that the presence of 6 precipitates along the grain boundaries leads to an improvement in creep-crack growth resistance.…”

Section: Effect Of Grain Size and Grain Boundary Morphologymentioning

confidence: 99%

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Elevated Temperature Fatigue Crack Growth in Alloy 718—part Ii: Effects of Environmental and Material Variables

Ghonem

Nicholas

Pineau

1993

Fatigue Fract Eng Mat Struct

105

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Observations concerning the effects of the environment and material variables on the crack growth process in alloy 718 are reviewed and analyzed on the basis of deformation characteristics in the crack tip region. The review of the role of material variables has focused on the effects of chemical composition and microstructure parameters including precipitate size and morphology as well as grain size and morphology. These analyses have suggested that

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Section: Effect Of Grain Size and Grain Boundary Morphologysupporting

confidence: 62%

Section: Effect Of Grain Size and Grain Boundary Morphologymentioning

confidence: 99%

Elevated Temperature Fatigue Crack Growth in Alloy 718—part Ii: Effects of Environmental and Material Variables

Ghonem

Nicholas

Pineau

1993

Fatigue Fract Eng Mat Struct

105

View full text Add to dashboard Cite

show abstract

“…Accordingly, this zone will be weak. The second view is that the presence of the S-phase at the grain boundaries is good for the high temperature stress rupture and crack growth properties (9,10,14,18,20,21,24,25,53,54,57). This latter view seems at fust glance to be in conflict with the first view as well as with our observations.…”

Section: Introductioncontrasting

confidence: 53%

Grain Boundary δ-Phase Morphologies, Carbides and Notch Rupture Sensitivity of Cast Alloy 718

Sjöberg¹,

Ingesten²,

Carlson³

1991

Superalloys 718, 625 and Various Derivatives (1991)

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Notch sensitivity has been connected with the presence of a film-like s-phase morphology in the grain boundaries of cast test bars of Alloy 718 of a problem material in which premature fracture occurred during testing of smooth stress rupture bars at 650 "C. A heat treatment designed to produce a plate-like S-phase morphology at the grain boundaries improved the material dramatically. Comparison with a reference material indicated the that the presence of coarse MC-carbides (0.9NbO.lTiC) at the grain boundaries attributed to the notch sensitivity problem. The degradation of the material by the carbides seems to be due to a considerable swelling action during a selective oxidation of these carbides. Additionally, a formation of a liquid phase at the carbides was confirmed. The volume increase of the selectively oxidized carbides was demonstrated by a an experiment in which two pieces of cast Alloy 718 with polished surfaces facing one another were pressed together and exposed to air at 650 "C for one hour.

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“…The compact produced from PSD A given a supersolvus heat treatment shows an average grain size of 10 µm, whilst the compact produced from PSD B gives an average grain size of 21 µm for the same heat treatment. All microstructures from both sub-and supersolvus heat treatments show some GBs that are relatively spherical, implying Zener pinning of the GBs by the PPBs, [3,6]. This is most apparent in the PSD A compact material.…”

Section: Microstructure and Grain Sizementioning

confidence: 99%

Microstructure and Mechanical Properties of an Advanced Nickel-Based Superalloy in the as-HIP Form

May

Hardy

Bache

et al. 2011

AMR

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Abstract. This study evaluates the suitability of as-hot isostatically pressed (HIP) RR1000 for noncritical applications in aero-engine components. RR1000, an advanced powder nickel-based superalloy, was developed for disc rotor components in aero-engines. For these critical applications, the consolidated alloy powder particles are extruded to break down carbide and oxide networks, known as prior particle boundaries (PPBs), and to refine the structure into a fine grain size for isothermal forging. In this study, hot isostatically pressed compacts, made from two different powder particle size fractions have been assessed following heat treatments below and above the gamma prime solvus temperature. A microstructural evaluation shows a greater degree of PPB decoration occurs in the finer powder particle size fraction. Following a super-solvus heat treatment these PPBs pin grain boundaries of the fine powder particle size compacts, whilst the reduction of PPB decoration in coarse powder particle compacts allows significant grain growth. Tensile test results of as-HIP RR1000 show, good yield strengths, ultimate tensile strengths and ductility, which are comparable with extruded and isothermal forged RR1000 disc material. Dwell crack propagation tests show that finer powder particle size compacts, which have received a sub-solvus heat treatment, give the highest crack growth rates; whilst the remaining material conditions show markedly improved crack growth resistance. In conclusion, as-HIP RR1000 demonstrates clear potential for use in non-critical applications, employing either powder particle size fraction used in this study subject to the appropriate solution heat treatment.

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The Influence of Microstructure upon the Creep and Fatigue Crack Growth Behaviour in Inconel 718

Cited by 6 publications

References 10 publications

Elevated Temperature Fatigue Crack Growth in Alloy 718—part Ii: Effects of Environmental and Material Variables

Elevated Temperature Fatigue Crack Growth in Alloy 718—part Ii: Effects of Environmental and Material Variables

Grain Boundary δ-Phase Morphologies, Carbides and Notch Rupture Sensitivity of Cast Alloy 718

Microstructure and Mechanical Properties of an Advanced Nickel-Based Superalloy in the as-HIP Form

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The Influence of Microstructure upon the Creep and Fatigue Crack Growth Behaviour in Inconel 718

Cited by 6 publications

References 10 publications

Elevated Temperature Fatigue Crack Growth in Alloy 718—part Ii: Effects of Environmental and Material Variables

Elevated Temperature Fatigue Crack Growth in Alloy 718—part Ii: Effects of Environmental and Material Variables

Grain Boundary &#948;-Phase Morphologies, Carbides and Notch Rupture Sensitivity of Cast Alloy 718

Microstructure and Mechanical Properties of an Advanced Nickel-Based Superalloy in the as-HIP Form

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Product

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About

Grain Boundary δ-Phase Morphologies, Carbides and Notch Rupture Sensitivity of Cast Alloy 718