Analysis of high-temperature creep deformation in a polycrystalline nickel-base superalloy

Soula, Aurélie; Renollet, Y.; Boivin, Denis; Pouchou, Jean-Louis; Locq, Didier; Caron, Pierre; Bréchet, Y.

doi:10.1016/j.msea.2008.04.122

Cited by 41 publications

(19 citation statements)

References 9 publications

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“…The specimens after failure at 850°C under 100 MPa, had a non-homogenous diameter due to the difference in grain size in the heat-affected area close to the weld joint. At this temperature, diffusion creep is mainly active for fine grain materials, with the grain boundary sliding acting as a rate controlling parameter for creep strains in excess of 1% [20][21][22]. The creep damage mechanisms in the LFWed samples will be discussed in detail in the following sections.…”

Section: Creep Testing Of Pwhted Joints At 700°c and 850°cmentioning

confidence: 99%

High temperature creep properties of a linear friction welded newly developed wrought Ni-based superalloy

Masoumi

Thébaud

Shahriari

et al. 2018

Materials Science and Engineering: A

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AD730 TM Ni-based superalloy specimens in solution-treated conditions were linear friction welded. Then, post-weld heat treatment (PWHT), consisting of γ´ sub-solvus solution treatments followed by aging, was conducted on the linear friction welded samples. High temperature creep tests were performed on the as-welded and PWHTed joints at two different temperatures: 700°C under 600 and 750 MPa stress levels, and 850°C under 100 and 200 MPa stresses. The creep resistance of the PWHTed joints was higher than that of the as-welded samples. The PWHTed joints exhibited better ductility than that of the base material at 850°C, while they showed slightly lower creep life at 700°C in comparison to the base metal. Microstructure examination showed that cracks initiated at the interface of oxidized particles at 700°C. The decrease in creep resistance of the AD730 TM Ni-based superalloy at 850°C was related to a combination of the formation of precipitate-free zones (PFZ) in the vicinity of the grain boundaries (GBs) and microcracking assisted by oxidation. The Larson-Miller Parameter (LMP) was used to correlate the creep strength, temperature and time to failure for the as-welded and PWHTed samples. LMP values varied between 21.5×10 3 and 24.5×10 3. It was found that in the investigated temperature range, the PWHTed AD730 TM has similar creep characteristics as Udimet TM 720 Li and Inconel 738LC at low values of LMP and better creep properties than those of the Inconel 617 alloy at higher LMP values.

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Section: Creep Testing Of Pwhted Joints At 700°c and 850°cmentioning

confidence: 99%

High temperature creep properties of a linear friction welded newly developed wrought Ni-based superalloy

Masoumi

Thébaud

Shahriari

et al. 2018

Materials Science and Engineering: A

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“…Soula et. al determined that hafniumoxide was a viable candidate for patterns for elevated temperature testing of nickel-based superalloys [13]. Therefore, a pattern of hafnium-oxide was created using electron beam lithography for this study.…”

Section: In-situ Mechanical Testingmentioning

confidence: 99%

“…GBS occurs when creep strain is accommodated by grains displacing relative to each other, and must be accompanied by intra-granular dislocation motion [11,12]. Preliminary findings on modern turbine disc alloys have indicated that GBS is a contributing creep deformation mechanism around 700°C [13], and intentionally creating micro-scale serrated grain boundaries increases creep resistance by limiting GBS [14]. Soula et al used a full-field digital image correlation (DIC) technique to conclude that GBS was active at conventional creep strain rates [13].…”

Section: Introductionmentioning

confidence: 99%

“…Preliminary findings on modern turbine disc alloys have indicated that GBS is a contributing creep deformation mechanism around 700°C [13], and intentionally creating micro-scale serrated grain boundaries increases creep resistance by limiting GBS [14]. Soula et al used a full-field digital image correlation (DIC) technique to conclude that GBS was active at conventional creep strain rates [13]. These studies have not included a detailed examination of the dislocation activity and its correlation with GBS, which is necessary to understand the mechanisms of GBS and why it occurs selectively.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Characterization of Strain Accommodation at Grain Boundaries of Nickel-based Superalloys

Carter¹,

Zhou²,

Sosa³

et al. 2012

Superalloys 2012 (Twelfth International Symposium)

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Elevated temperature in-situ experiments, local crystallographic mapping and digital image correlation techniques have been used to gain insight into strain localization near grain boundaries in polycrystalline René-104. Samples were heat treated to create either smooth (standard) or serrated grain boundaries. Deformation experiments concluded that strain tended to localize at triple points and special boundaries in the standard microstructure, while strain had a less-pronounced correlation in the serrated microstructure. Both materials exhibited grain boundary sliding (GBS), but the standard microstructure proved to be more susceptible. Site-specific extraction of TEM foils indicated that boundaries that exhibited strain localization experienced activation of multiple slip systems, while boundaries showing GBS showed activation of only a single slip system. Based on m′ analysis, slip transmission was expected to be difficult in boundaries that exhibited strain localization while boundaries that showed sliding allowed for easy slip transmission. A volume containing a boundary that exhibited GBS was analyzed to assess boundary surface topography and indicated that the boundary was macroscopically planer with local deviations that were on the order of the secondary γ′ size.

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“…The mechanism depends on the temperature and the stress level. The dependence of the superalloy behavior on deformation conditions has been extensively analyzed in the last several years both for polycrystalline 8–11 and single crystal-based superalloys. 12–14 As is the case for other alloys reinforced with a dispersed hard second phase, the volume fraction of the γ' precipitates, and their mean size and spacing have a major effect on the mechanical properties of these superalloys.…”

Section: Introductionmentioning

confidence: 99%

Development of a model for simulation of micro-twin and corresponding asymmetry in high temperature deformation behavior of nickel-based superalloy single crystals using crystal plasticity-based framework

Samal

2016

Proceedings of the Institution of Mechanical Engineers, Part C:

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Development of reliable computational models to predict the high temperature deformation behavior of nickel-based superalloys is in the forefront of materials research. These alloys find wide applications in manufacturing of turbine blades and discs of aircraft engines. The microstructure of these alloys consists of the primary γ′-phase, and the secondary and tertiary precipitates (of Ni3Al type) are dispersed as γ′-phases in the gamma matrix. It is computationally expensive to incorporate the explicit finite element model of the γ-γ′ microstructure in a crystal plasticity-based constitutive framework to simulate the response of the polycrystalline microstructure. Existing models in literature do not account for these underlying micro-structural features which are important for simulation of polycrystalline response. The aim of this work is to develop a physically motivated multi-scale approach for simulation of high temperature response of nickel-based superalloys. At the lower length scale, a dislocation density-based crystal plasticity model is developed which simulates the response of various types of microstructures. The microstructures are designed with various shapes and volume fractions of γ′-precipitates. A new model for simulation of the mechanism of anti-phase boundary shearing of the γ′-precipitates, by the matrix dislocations, is developed in this work. The lower scale model is homogenized as a function of various micro-structural parameters, and the homogenized model is used in the next scale of multi-scale simulation. In addition, a new criterion for initiation of micro-twin and a constitutive model for twin strain accumulation are developed. This new micro-twin model along with the homogenized crystal plasticity model has been used to simulate the creep response of a single crystal nickel-based superalloy, and the results have been compared with those of experiment from literature. It was observed that the new model has been able to model the tension–compression asymmetry as observed in single crystal experiments.

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Analysis of high-temperature creep deformation in a polycrystalline nickel-base superalloy

Cited by 41 publications

References 9 publications

High temperature creep properties of a linear friction welded newly developed wrought Ni-based superalloy

High temperature creep properties of a linear friction welded newly developed wrought Ni-based superalloy

Characterization of Strain Accommodation at Grain Boundaries of Nickel-based Superalloys

Development of a model for simulation of micro-twin and corresponding asymmetry in high temperature deformation behavior of nickel-based superalloy single crystals using crystal plasticity-based framework

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