Creep deformation mechanisms and CPFE modelling of a nickel-base superalloy

Li, Muzi; Pham, Minh‐Son; Peng, Zichao; Tian, Guohui; Shollock, Barbara A.

doi:10.1016/j.msea.2018.01.100

Cited by 22 publications

(9 citation statements)

References 19 publications

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“…[48,49] It has been known that the deposition and subsequent reactions of dislocations at the γ/γ' interface in the plasticity-assisted creep of nickel superalloys at high temperatures create superdislocations that shear γ' driven by the increase in stress field induced by the following dislocations of the same slip system. [49][50][51] Extended faults (that are typically observed when superdislocations shear γ' [52,53] ) were not seen in our observations due to the orientation of observations similar to what was shown in another study. [51] It is likely that the same dislocation reaction as seen in ref.…”

Section: Discussionsupporting

confidence: 89%

Dislocation Arrangements and Cyclic Microplasticity Surrounding Stress Concentration in a Ni‐Based Single‐Crystal Superalloy

Piglione,

Bellamy,

et al. 2023

Adv Eng Mater

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Local cyclic plasticity near stress concentrations governs the fatigue crack initiation in cyclicly loaded Ni‐based single‐crystal superalloys, but has not been well studied and understood. We presents the first TEM‐based site‐specific study of plasticity in the crack initiation region in a notched single‐crystal superalloy subjected to fatigue testing at 800 °C, coupling it with microstructure‐based crystal plasticity modelling. Detailed TEM examinations show that local plasticity near the notch significantly differed from bulk plasticity, featuring high dislocation densities and distinctive arrangements of dislocation pairs within the γ’ precipitates. It further shows that the increased local stresses alone were responsible for the increase in dislocation density and extensive γ’ shearing, but not for the distinctive arrangement of dislocation pairs seen in the notch vicinity, thus highlighting the considerable role played by the local variations in loading rates and stress state surrounding the notch. The results of this work provide new fundamental insights into the deformation micro‐mechanisms leading to fatigue crack initiation in single‐crystal superalloys.This article is protected by copyright. All rights reserved.

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Section: Discussionsupporting

confidence: 89%

Dislocation Arrangements and Cyclic Microplasticity Surrounding Stress Concentration in a Ni‐Based Single‐Crystal Superalloy

Piglione,

Bellamy,

et al. 2023

Adv Eng Mater

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Section: Results and Analysismentioning

confidence: 99%

“…On the one hand, high temperature and high stress are favorable factors for the precipitation of tertiary phases; on the other hand, the increased time or elevated temperature will lead to dissolution. [4,35,36] The accumulation of dislocations is an important factor causing the alloy damage. Figure 14a demonstrates that microtwins and grain boundaries impede dislocation motion and cause dislocation accumulation.…”

Section: Degradation Of Microstructurementioning

confidence: 99%

High‐Temperature Creep Behavior and Damage Mechanism of an Advanced Powder Metallurgy Ni‐Based Superalloy

Li,

Zhang,

et al. 2024

Adv Eng Mater

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The creep behavior of a novel PM Ni‐based superalloy was investigated at temperatures ranging from 760 °C to 815 °C and stress levels in the 480 MPa‐620 MPa. The steady‐state creep rate, strain to rupture, and rupture time were analyzed based on the Monkman‐Grant relation and the modified Monkman‐Grant relation. The creep damage factor was redefined by the analysis of Monkman‐Grant ductility. A general relationship between the time reaching Monkman‐Grant ductility and creep life was established. The sharply accelerated creep stage was proposed and the modified Monkman‐Grant relation of the transient creep parameters in this stage was established. The nucleation, growth and connection of grain boundary creep cavities dominated the creep damage of the alloy. The stress concentration caused by the accumulation of dislocations at grain boundaries and σ phase interfaces, and the grain boundary slipping were the main reason for the nucleation of grain boundary cavities. The coupling effect of the temperature and the stress aggravates the damage of grain boundary and the degradation of microstructure.This article is protected by copyright. All rights reserved.

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“…CP modeling of creep historically has been limited to single crystal simulations of Ni-based super alloys [30,31]. Only in the last couple years have polycrystalline models with dislocation climb mechanisms been developed for high temperature creep modeling [32], such as a model for Grade 91 including particle coarsening [33].…”

Section: Introductionmentioning

confidence: 99%

“…Note that expression (3) for opening rate does not include a term involving b  which is postulated in [77] and subsequent works [51,52]. The authors motivate this simpler expression (3) for continuous nucleation of spherical cavities in appendix A expression (32) by returning to the principal modeling assumptions.…”

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confidence: 99%

Combined crystal plasticity and grain boundary modeling of creep in ferritic-martensitic steels: I. Theory and implementation

Nassif

Truster

et al. 2019

Modelling Simul. Mater. Sci. Eng.

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This paper presents a physically-based microstructural model for creep rupture at 600 °C for Grade 91 steel. The model includes constitutive equations that reflect various observed phenomena in Grade 91, and it is incorporated into a mesoscale finite element model with explicit geometry for the prior austenite grains and grain boundaries. Creep within the grains is represented using crystal plasticity for dislocation motion and recovery along with linear viscous diffusional creep for point defect diffusion. The grain boundary models include physics-based models for cavity growth and nucleation that accurately capture tertiary creep and creep rupture. Simulations of creep at 100 MPa are performed, and the contribution of each mechanism is analyzed. The overarching goal is to gain a mechanistic understanding of the material to improve the prediction of creep rupture for long service lives in elevated temperature operating conditions. The creep response of the material at different stress levels, stress states, and temperatures is studied in Part 2 of this paper in order to determine the implications of the simulations on high temperature design practice. Furthermore, the second part explores the effect of triaxial stress states on the creep response and finds a transition from notch-strengthening behavior at high stress to notch-weakening behavior at lower stresses.

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Creep deformation mechanisms and CPFE modelling of a nickel-base superalloy

Cited by 22 publications

References 19 publications

Dislocation Arrangements and Cyclic Microplasticity Surrounding Stress Concentration in a Ni‐Based Single‐Crystal Superalloy

Dislocation Arrangements and Cyclic Microplasticity Surrounding Stress Concentration in a Ni‐Based Single‐Crystal Superalloy

High‐Temperature Creep Behavior and Damage Mechanism of an Advanced Powder Metallurgy Ni‐Based Superalloy

Combined crystal plasticity and grain boundary modeling of creep in ferritic-martensitic steels: I. Theory and implementation

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