The diffusion and trapping of hydrogen in steel

Oriani, R. A.

doi:10.1016/0001-6160(70)90078-7

Cited by 1,470 publications

(644 citation statements)

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“…Effective diffusion coefficients as a function of temperature are extracted from the computations and validated using the standard theory of trapping at lattice defects. 13,21,22,26 …”

Section: Results and Discussion: Parameterization Of Energy Barrmentioning

confidence: 99%

“…provide low energy trapping sites within the lattice and retard the overall diffusion. 13,[21][22][23][24][25][26] The existence of these traps plays an important role in the retention of hydrogen within the bulk, given the low solubility of hydrogen in iron. 1 Furthermore, when trapping occurs at interfaces such as matrix/second-phase particles, grain boundaries, microcracks, etc., the cohesive strength of these interfaces is compromised, thereby promoting decohesion and/or emission of dislocations.…”

Section: Introductionmentioning

confidence: 99%

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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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“…Effective diffusion coefficients as a function of temperature are extracted from the computations and validated using the standard theory of trapping at lattice defects. 13,21,22,26 …”

Section: Results and Discussion: Parameterization Of Energy Barrmentioning

confidence: 99%

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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“…It is also assumed that hydrogen is introduced via gas phase charging with p H2 = 1 bar and local equilibrium is achieved. If θ is negligible against unity, (5) shows that θ is proportional to c. The balance of diffusing hydrogen in a volume element leads to a differential equation similar to the second Fick's law, where the lattice diffusion coefficient D L is replaced by an apparent diffusion coefficient D app . As pointed out by Oriani and assuming local equilibrium and θ 1 [5]:…”

Section: Characterization Of Traps Through a Single Permeation Transientmentioning

confidence: 99%

“…The hypothesis of local equilibrium proposed by Oriani [5] is assumed here. This hypothesis implies that the detrapping time constant (1/ρ) is much lower than the diffusion time constant (L 2 /D L ).…”

Section: Characterization Of Traps Through a Single Permeation Transientmentioning

confidence: 99%

“…These authors [2,3] do not compare simulated transients with experimental ones. One attempt to fit simulated permeation transients to experimental data is that of Johnson and Lin [4], which assumes the simplification of local equilibrium theory proposed in 1970 by Oriani [5]. The experimental data correspond to hydrogen permeation through cold rolled iron with gas phase charging and electrochemical detection, and the discussion is centered on whether the traps are saturable or not.…”

Section: Introductionmentioning

confidence: 99%

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Numerical Study of Hydrogen Trapping: Application to an API 5L X60 Steel

Castaño-Rivera¹,

Ramunni²,

Bruzzoni³

2012

ISRN Materials Science

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A numerical finite difference method is developed here to solve the diffusion equation for hydrogen in presence of trapping sites. A feature of our software is that an optimization of diffusion and trapping parameters is achieved via a non linear least squares fit. On the other hand, we have demonstrated that usual electrochemical hydrogen permeation tests are enough to assess hydrogen free energies of trapping in the range of −35 kJ/mol to −70 kJ/mol. These conclusions are obtained by assuming the presence of saturable traps in local equilibrium with hydrogen and are validated by means of simulated permeation and degassing transients. In addition, we check our model performing electrochemical hydrogen permeation tests at 30 • C, 50 • C, and 70 • C, on an API 5L X60 as received steel state to study its trapping and diffusion properties considering only one type of trapping site. The binding energies (ΔG) and the trap densities (N) are determined by fitting the theoretical model to the experimental permeation data. The steel presents a high density of weak traps, |ΔG| < 35 KJ/mol, namely, N = 1.4 × 10 −5 mol cm −3 . Strong trapping sites which alter the shape of the permeation transient are also detected; their ΔG values ranged from 57 to 72 KJ/mol.

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Study of Isotope Effects in the Hydrogen Transport of an 8% CrWVTa Martensitic Steel

Esteban¹,

Sedano²,

Perujo³

et al. 2001

phys. stat. sol. (a)

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A time-dependent gas-phase isovolumetric desorption technique has been used to assess the isotope effects in the diffusive transport parameters of hydrogen in an 8% CrWVTa reduced activation martensitic steel in the temperature range of 423-892 K and driving pressures from 4 Â 10 4 -1 Â 10 5 Pa. The experiments have been run with both protium and deuterium obtaining their respective transport parameters, diffusivity ðDÞ, Sieverts' constant ðK S Þ, permeability ðFÞ, trap site density ðh t Þ and the trapping activation energy ðE t Þ. Isotope effects on steel are analysed and compared with a-iron. A new way to derive more accurate tritium transport parameters is proposed.

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The diffusion and trapping of hydrogen in steel

Cited by 1,470 publications

References 9 publications

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

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

Numerical Study of Hydrogen Trapping: Application to an API 5L X60 Steel

Study of Isotope Effects in the Hydrogen Transport of an 8% CrWVTa Martensitic Steel

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