Development of fatigue crack growth testing under thermo-mechanical fatigue conditions

Jacques, S.; Lynch, M.; Wisbey, A.; Stekovic, Svjetlana; Williams, S.

doi:10.1179/096034013x13631093463744

Cited by 2 publications

(3 citation statements)

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“…Seven locations were selected for thermocouples, similar to those presented by Jacques et al [ 25 ], to monitor the thermal profiles across the specimen. Figure 3 shows the locations used for the current work, showing five thermocouples around the notch plane on the faces and corners, with a set 2 mm above the plane at the notch and a set 2 mm below.…”

Section: Resultsmentioning

confidence: 99%

Thermo-Mechanical Fatigue Crack Growth of RR1000

2017

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Non-isothermal conditions during flight cycles have long led to the requirement for thermo-mechanical fatigue (TMF) evaluation of aerospace materials. However, the increased temperatures within the gas turbine engine have meant that the requirements for TMF testing now extend to disc alloys along with blade materials. As such, fatigue crack growth rates are required to be evaluated under non-isothermal conditions along with the development of a detailed understanding of related failure mechanisms. In the current work, a TMF crack growth testing method has been developed utilising induction heating and direct current potential drop techniques for polycrystalline nickel-based superalloys, such as RR1000. Results have shown that in-phase (IP) testing produces accelerated crack growth rates compared with out-of-phase (OOP) due to increased temperature at peak stress and therefore increased time dependent crack growth. The ordering of the crack growth rates is supported by detailed fractographic analysis which shows intergranular crack growth in IP test specimens, and transgranular crack growth in 90 • OOP and 180 • OOP tests. Isothermal tests have also been carried out for comparison of crack growth rates at the point of peak stress in the TMF cycles.

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Section: Resultsmentioning

confidence: 99%

Thermo-Mechanical Fatigue Crack Growth of RR1000

2017

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“…Although the high stress state at the crack tip with high ΔK level can promote the occurrence of creep damage as seen in RR1000, the creep damage may not have time to fully develop if the crack tip advances quickly enough at a high ΔK level as seen in Udimet 720Li. Ni-based superalloys [119][120][121], which is supported by the higher FCG rates associated with intergranular fractography under the in-phase (IP) loading conditions compared with out-of-phase (OP) testing associated with transgranular fractography, due to the increased temperature at peak stress and therefore increased time-dependent FCG. A few reviews of the interaction between environmental damage and fatigue in Ni-based superalloys can be found in [4,21,109].…”

Section: Creep-fatigue Crack Growthmentioning

confidence: 99%

“…Fatigue of materials is a well-established and important research area with a long history. [120,156].…”

Section: Perspectives and Concluding Remarksmentioning

confidence: 99%

Fatigue crack growth mechanisms in powder metallurgy Ni-based superalloys—A review

Jiang

Song

Reed

2020

International Journal of Fatigue

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Powder metallurgy (PM) Ni-based superalloys are widely used for aeroengine turbine disc applications due to their excellent mechanical properties and good corrosion resistance at elevated temperatures. Understanding the fatigue crack growth (FCG) mechanisms of PM Ni-based superalloys is important for both disc alloy development and life prediction of disc components in these advanced aeroengines where damage tolerance design prevails. FCG in PM Ni-based superalloys is a complicated function of microstructure, temperature, loading conditions and environment and is usually a consequence of the synergistic effects of fatigue, creep and environmental damage. In this review, the mechanisms controlled by microstructural features including grain size, grain misorientation, γ′ size and distribution on short and long FCG behaviour in PM Ni-based superalloys are discussed. The contribution of creep and environmental damage to FCG has been critically assessed. The competing effects of mechanical damage (i.e. fatigue and creep) and environmental damage at the crack tip are microstructure-sensitive, and usually results in transition between transgranular, mixed-trans-intergranular and intergranular FCG depending on the contribution of environmental damage to FCG processes.

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Development of fatigue crack growth testing under thermo-mechanical fatigue conditions

Cited by 2 publications

References 0 publications

Thermo-Mechanical Fatigue Crack Growth of RR1000

Thermo-Mechanical Fatigue Crack Growth of RR1000

Fatigue crack growth mechanisms in powder metallurgy Ni-based superalloys—A review

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