A micromechanics approach to the study of hydrogen transport and embrittlement

Taha, Ahmed; Sofronis, Petros

doi:10.1016/s0013-7944(00)00126-0

Cited by 202 publications

(115 citation statements)

References 99 publications

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“…Equation [3] neglects H trapping at crack tip dislocation structure. [49,52,53] Research on H uptake and diffusion in Monel K-500, [29] extended in the present research, establishes the applied cathodic potential dependence of crack tip C H-Diff necessary to implement the models in Eqs. [1] through [3].…”

Section: Introductionmentioning

confidence: 70%

“…[1]. The discrete dislocation model (maximum hydrostatic stress~20 r YS at 20 to 100 nm beneath the crack tip) [41,81,82] and a blunted crack finite element model (maximum hydrostatic stress 3 to 5 r YS at 2 to 5 lm) [52,53] bound the crack tip stress field relevant for HEAC modeling. This latter hydrostatic stress may be increased if strain gradient plasticity impacts the crack tip stress distribution.…”

Section: E Threshold For Heacmentioning

confidence: 99%

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Measurement and Modeling of Hydrogen Environment-Assisted Cracking in Monel K-500

Gangloff

Burns

et al. 2014

Metall Mater Trans A

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Hydrogen environment-assisted cracking (HEAC) of Monel K-500 is quantified using slow-rising stress intensity loading with electrical potential monitoring of small crack propagation and elastoplastic J-integral analysis. For this loading, with concurrent crack tip plastic strain and H accumulation, aged Monel K-500 is susceptible to intergranular HEAC in NaCl solution when cathodically polarized at À800 mV SCE (E A , vs saturated calomel) and lower. Intergranular cracking is eliminated by reduced cathodic polarization more positive than À750 mV SCE . Crack tip diffusible H concentration rises, from near 0 wppm at E A of À765 mV SCE , with increasing cathodic polarization. This behavior is quantified by thermal desorption spectroscopy and barnacle cell measurements of hydrogen solubility vs overpotential for planar electrodes, plus measured-local crevice potential, and pH scaled to the crack tip. Using crack tip H concentration, excellent agreement is demonstrated between measurements and decohesion-based model predictions of the E A dependencies of threshold stress intensity and Stage II growth rate. A critical level of cathodic polarization must be exceeded for HEAC to occur in aged Monel K-500. The damaging-cathodic potential regime likely shifts more negative for quasi-static loading or increasing metallurgical resistance to HEAC.

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Section: Introductionmentioning

confidence: 70%

Section: E Threshold For Heacmentioning

confidence: 99%

Measurement and Modeling of Hydrogen Environment-Assisted Cracking in Monel K-500

Gangloff

Burns

et al. 2014

Metall Mater Trans A

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“…Some of these studies have already been alluded to before and we note next a few more works that have sought to model the overall embrittlement process rather than individual mechanisms. At the continuum level, Sofronis and coworkers 37,[42][43][44] have used finite element studies extensively to model the interaction of hydrogen with cracks and notches. A brief survey with further references may be found in Ref.…”

Section: Introductionmentioning

confidence: 99%

“…A brief survey with further references may be found in Ref. 44. The primary features of these models are stress-assisted diffusion and an elasto-plastic constitutive law (J2 plasticity) for material response; additional constitutive assumptions need to be made to capture hydrogeninduced dilatation, trap generation with plastic strain, and changes in local elastic moduli with hydrogen concentration.…”

Section: Introductionmentioning

confidence: 99%

Effect of atomic scale plasticity on hydrogen diffusion in iron: Quantum mechanically informed and on-the-fly kinetic Monte Carlo simulations

et al. 2008

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We present an off-lattice, on-the-fly kinetic Monte Carlo (KMC) model for simulating stress-assisted diffusion and trapping of hydrogen by crystalline defects in iron. Given an embedded atom (EAM) potential as input, energy barriers for diffusion are ascertained on the fly from the local environments of H atoms. To reduce computational cost, on-the-fly calculations are supplemented with precomputed strain-dependent energy barriers in defect-free parts of the crystal. These precomputed barriers, obtained with high-accuracy density functional theory calculations, are used to ascertain the veracity of the EAM barriers and correct them when necessary. Examples of bulk diffusion in crystals containing a screw dipole and vacancies are presented. Effective diffusivities obtained from KMC simulations are found to be in good agreement with theory. Our model provides an avenue for simulating the interaction of hydrogen with cracks, dislocations, grain boundaries, and other lattice defects, over extended time scales, albeit at atomistic length scales.

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“…For stress-assisted hydrogen diffusion simulation, the flux boundary condition is used. The boundary conditions that are used in the simulations of HE are either the Dirichlet condition or a prescribed concentration boundary concentration [26]. Based on their study, Turnbull et al [45] support the use of the flux boundary condition, especially in materials with high hydrogen diffusivity.…”

Section: (C) Boundary Conditionmentioning

confidence: 99%

A comprehensive analysis of the growth rate of stress corrosion cracks

2015

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This paper is a synthesis of earlier results supplemented by new results to define a comprehensive analysis of the growth rate of stress corrosion cracking (SCC). Two mechanisms, anodic dissolution (AD) and hydrogen embrittlement (HE), have been considered to calculate the SCC growth rate of AA 7050-T6 for a surface-breaking crack with blunt tip in an aqueous environment. The relative contributions of each mechanism and their mutual interactions have been quantitatively assessed. Results show that AD provides critical conditions for HE, which explains in part a stepwise propagation of the crack. Finally, the total crack growth rate due to the combined effects of AD and HE has been determined, and numerical results have been compared with experimental data, and a calculation of the crack growth rate for a practical configuration has been presented.

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A micromechanics approach to the study of hydrogen transport and embrittlement

Cited by 202 publications

References 99 publications

Measurement and Modeling of Hydrogen Environment-Assisted Cracking in Monel K-500

Measurement and Modeling of Hydrogen Environment-Assisted Cracking in Monel K-500

Effect of atomic scale plasticity on hydrogen diffusion in iron: Quantum mechanically informed and on-the-fly kinetic Monte Carlo simulations

A comprehensive analysis of the growth rate of stress corrosion cracks

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