Microstructural aspects of fatigue in Ni-base superalloys

Antolovich, Stephen D.

doi:10.1098/rsta.2014.0128

Cited by 45 publications

(27 citation statements)

References 80 publications

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“…Based on this, assuming purely Lorentzian (Eq. [1]) or purely Gaussian profiles (Eq. [2]), the measured XRD peak width can be expressed as a superposition of two broadening components, one for size and the other for strain, respectively.…”

Section: A Breadth Methodsmentioning

confidence: 99%

“…Accordingly, in Eqs. [1] and [2], terms K/D and K 2 /D 2 account for size broadening, while e and e 2 account for strain broadening.…”

Section: A Breadth Methodsmentioning

confidence: 99%

“…These alloys also find applications in chemical industry where they withstand both elevated temperatures and strong corrosives, such as brines, carbonates, phosphates, chlorides, nitrates, as well as seawater. [1][2][3][4] The essential solute elements in Ni-base superalloys are Al and/or Ti and their total concentration is generally less than 10 at. pct.…”

Section: Introductionmentioning

confidence: 99%

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Inhomogeneous Strains and Dislocation Evolution in Surface-Treated Ni-Base Superalloys

Shukla¹,

Lim

Dong

2020

Metall Mater Trans A

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Surface treatment processes such as shot-peening create near-surface residual stresses in the component, which retard the initiation and growth of fatigue cracks. These processes, however, also induce considerable amount of strain hardening and alter the sub-surface dislocation structure of the material, which can impact its mechanical and electrochemical properties. Although these effects are critical for part performance, they have not so far been studied for surface-treated Ni-base superalloys, which are widely used for load-bearing applications. To address this, we have developed an X-ray diffraction (XRD) framework based on Convolutional Multiple Whole Profile (CMWP) fitting approach that can be used to quantify dislocation densities in shot-peened Inconel 718 components. The method exploits physics-based mechanisms for size and strain broadening to model these effects and uses dislocation contrast factors to account for deformation-induced crystallographic anisotropy in the diffraction profile. Our results suggest that shot-peening leads to one order of magnitude increase in the dislocation density of Inconel 718 alloys, which is supported by direct evidence from transmission electron micrographs. The approach developed in this work can be extended to other types of Ni-base superalloys, enabling a simple non-destructive method to calculate dislocation densities in this commercially important class of materials.

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Section: A Breadth Methodsmentioning

confidence: 99%

“…Accordingly, in Eqs. [1] and [2], terms K/D and K 2 /D 2 account for size broadening, while e and e 2 account for strain broadening.…”

Section: A Breadth Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Inhomogeneous Strains and Dislocation Evolution in Surface-Treated Ni-Base Superalloys

Shukla¹,

Lim

Dong

2020

Metall Mater Trans A

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“…Towards the 'opposite' crystal/polycrystal/nanopolycrystal level of size scale, coverage is provided by Antolovich [47], Armstrong [48], Hohenwarter & Pippan [49], Ovid'ko [50] and Pineau [51]. Emphasis is given by these authors to the importance of crystal/grain boundaries.…”

mentioning

confidence: 99%

Fracturing across the multi-scales of diverse materials

Armstrong

Antolovich

Griffiths

et al. 2015

Phil. Trans. R. Soc. A.

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Everyone has to deal with fracturing of materials at one level or another, beginning from normal household chores and extending to the largest scale of observations reported for catastrophic events occurring on a geological level or even expanded to events in outer space. Such wide perspective is introduced in the current introduction of this theme issue. The follow-on organization of technical articles provides a flavour of the range in size scales at which fracturing occurs in a wide diversity of materials—from ‘fracking’ oil extraction and earth moving to laboratory testing of rock material and extending to the cracking of tooth enamel. Of important scientific interest are observations made and analysed at the smallest dimensions corresponding to the mechanisms by which fracture is either enhanced or hindered by permanent deformation or other processes. Such events are irrevocably linked to the atomic structure in all engineering materials, a sampling of which is presented, including results for crystalline and amorphous materials. Hooray for the broad subject description that is hoped to be appealing to the interested reader.

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“…The surface roughness and residual stresses inherent to the manufacturing process or imposed by the surface treatment also affect the component lifetime (e.g., shot-and laser-peening, deep rolling). Owing to the complex thermal and mechanical repeated cyclic loading conditions during the engine service, the initial stress field may relax, be redistributed or evolve, particularly at high temperature (see [2] and references therein). Nonlinear elasto-viscoplastic models coupled to creep and a fatigue damage model [3] enable the identification of fatigue critical zones and crack initiation time, depending on the thermal and mechanical history of the disk [4].…”

mentioning

confidence: 99%