Rejuvenation of Single-Crystal Ni-Base Superalloy Turbine Blades: Unlimited Service Life?

Ruttert, Benjamin; Horst, Oliver Martin; Lopez‐Galilea, Inmaculada; Langenkämper, Dennis; Kostka, Aleksander; Somsen, Christoph; Goerler, Johannes V.; Ali, Muhammad Adil; Shchyglo, Oleg; Steinbach, Ingo; Eggeler, Gunther; Theisen, W.

doi:10.1007/s11661-018-4745-6

Cited by 25 publications

(18 citation statements)

References 36 publications

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“…Therefore, this degraded microstructure will deteriorate the creep property of K465 alloy. Similar results were also previously reported on a single crystal Ni-base superalloy [32]. However, it is still not clear why the creep property of a sample with high accumulated strain cannot be fully rejuvenated by performing RHT.…”

Section: Effect Of Rht On the Creep Behavior Of K465 Alloysupporting

confidence: 86%

Effect of Rejuvenation Heat Treatment on the Creep Property and Microstructural Evolution of a Ni-Base Superalloy

2020

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Interrupted creep tests were performed on a polycrystalline Ni-base superalloy, and rejuvenation heat treatment (RHT) was carried out to restore the creep resistance. During creep deformation, the microstructural evolution can be characterized as coarsening and rafting of γ precipitates, formation of dislocation networks in matrix channels, γ shearing by dislocations and carbides transformation from MC to M 6 C type. In the sample with low precrept strain, the dislocation networks can be effectively removed after RHT and the size and morphology of γ particles were similar to that just after heat treatment. However, the microstructure in the sample with higher creep strain after RHT cannot be fully restored to the original state in terms of dislocations and distribution of γ particles. The subsequent creep results exhibit that creep property is also relevant to the precrept strain, which exhibits a good agreement with microstructure observations. In addition, RHT cannot reverse the carbide transformation from MC to M 6 C type but enhances this process, which can be evident by the change of the area fraction of these two types of carbides. The effect of carbides transformation on the creep resistance of K465 alloy is not pronounced.

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Section: Effect Of Rht On the Creep Behavior Of K465 Alloysupporting

confidence: 86%

Effect of Rejuvenation Heat Treatment on the Creep Property and Microstructural Evolution of a Ni-Base Superalloy

2020

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“…The limitations of these approaches are that they are much more time consuming and they require the knowledge of the initial distribution of elements in the as-cast state. The same applies regarding the optimization of the precipitate size during aging heat treatments using phase-field approaches [113][114][115][116][117] at the expanse of very simple and efficient mean-field Lifshitz-Slyozov-Wagner (LSW) models [118,119].…”

Section: 22) Optimizationsmentioning

confidence: 99%

“…No exception to this "rule of thumbs" can be noticed in the open literature for ~ <001> oriented components (the usual crystallographic orientation along the profile of blades) while it is known that the optimal precipitate edge length in terms of creep resistance for ~ <111> oriented SX specimens is around 200 nm [64]. This optimal precipitate size and regularity is also one of the targets to be reached for serviced components using rejuvenation procedures involving a ST and/or HIPping procedure after several hours of use [114,[120][121][122].…”

Section: ) Mechanical Properties Sensitivity To the Processing Parameters 41) Creep And Tensile Propertiesmentioning

confidence: 99%

Processing of directionally cast nickel-base superalloys: solidification and heat treatments

Cormier

Gandin

2022

Nickel Base Single Crystals Across Length Scales

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“…At present, two methods have been proposed to extend the lives of crept superalloys, which are hot isostatic pressing [7,8] and rejuvenation heat treatment [9][10][11]. Hot isostatic pressing shows great advantages in closing up the creep holes, while rejuvenation heat treatment, which employs much less complex equipment and auxiliaries, is more suitable to superalloy single crystal components after a certain period of service without many creep holes generated.…”

Section: Introductionmentioning

confidence: 99%

A new rejuvenation heat treatment of crept Ni-based superalloy single crystals

Lin

Shen²,

Zhou³

et al. 2022

IOP Conf. Ser.: Mater. Sci. Eng.

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Ni-based superalloys are widely used in harsh environments due to their exceptional high-temperature mechanical properties, and their microstructures are inevitably subjected to degradation, including accumulation of strain/stress, generation of high density of dislocations, and rafting of γ′-particles, under creep damage. To prolong their service life, rejuvenation heat treatment is proposed to restore their microstructure. In this study, a Ni-based superalloy single crystal specimen with 0.15% creep strain is taken as a surrogate of partially served components. The microstructure, including the dislocation density and distribution as well as the size and morphology of γ′-particles, is investigated. Then two comparative heat treatment protocols are applied to the crept superalloy single crystal. Because super-solvus homogenization treatment triggers recrystallization, a recovery pre-annealing step at sub-solvus temperature is designed to relieve the stored deformation energy. After homogenization and aging heat treatment, the single crystalline structure is preserved, and in the meanwhile the γ′-particles are restored to uniform cuboidal morphology and the dislocations are fully eliminated. Our findings provide a route to rejuvenate crept superalloy single crystals.

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Rejuvenation of Single-Crystal Ni-Base Superalloy Turbine Blades: Unlimited Service Life?

Cited by 25 publications

References 36 publications

Effect of Rejuvenation Heat Treatment on the Creep Property and Microstructural Evolution of a Ni-Base Superalloy

Effect of Rejuvenation Heat Treatment on the Creep Property and Microstructural Evolution of a Ni-Base Superalloy

Processing of directionally cast nickel-base superalloys: solidification and heat treatments

A new rejuvenation heat treatment of crept Ni-based superalloy single crystals

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