A more generalized analysis of hydrogen trapping

Iino, Makio

doi:10.1016/0001-6160(82)90216-4

Cited by 90 publications

(29 citation statements)

References 6 publications

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“…[3][4][5][6][7][8][9][10][11][12][13][14] Whilst analytical treatments often led to complex equations for the effective diffusivity and fractional occupancy, 3,8) they promoted greatly our understanding of the characteristics of diffusion and the nature of trapping of hydrogen in iron. On the other hand, computer modeling can meet practical requirements, e.g.…”

Section: Introductionmentioning

confidence: 99%

Modeling Thermal Desorption Analysis of Hydrogen in Steel

2006

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A computer model was developed to simulate the thermal desorption flux of hydrogen from steel specimens by an explicit finite difference method, which is convergent and stable for all time increment. The influences of experimental parameters, e.g. ramp rate, specimen size and duration of exposure at ambient temperature etc., on the desorption spectrum, concentration profile of hydrogen in the lattice and fractional occupancy at the trapping sites, were studied assuming that the major trapping sites were dislocations. The increase in ramp rate caused a marked shift in the desorption peak to a higher temperature, whilst the increase in the specimen size shifted the peak to higher temperatures to a moderate extent. The duration of exposure may have a considerable influence on the thermal desorption spectra when the desorption peak is associated with a lower binding energy trap site.

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Section: Introductionmentioning

confidence: 99%

Modeling Thermal Desorption Analysis of Hydrogen in Steel

2006

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“…[17] have been attributed to boundary-T 1 dissolution, [6] T 1 dissoTo fully understand the process of hydrogen embrittlelution with hydrogen uptake, [7] AlLiH 4 formation and crackment, one must establish a fundamental understanding of ing, [8,9] dissolution of copper-depleted zones, [10] and intrinsic the ingress, transport, and trapping of hydrogen in a material hydrogen embrittlement involving mobile and or trapped system. [18,19] This article serves as a first step to developing hydrogen. [11] Which of these or other metallurgical factors such an understanding.…”

Section: Introductionmentioning

confidence: 99%

The identification of hydrogen trapping states in an Al-Li-Cu-Zr alloy using thermal desorption spectroscopy

Smith

Scully

2000

Metall Mater Trans A

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Thermal desorption spectroscopy (TDS) was utilized to identify several metallurgical states in an Al2Li -2Cu-0.1Zr (wt pct) alloy, which trap absorbed hydrogen. Six distinct metallurgical desorption states for hydrogen were observed for tempers varying from the T3 to peakaged condition. Lower energy thermal desorption states were correlated with interstitial sites, lithium in solid solution, and ␦Ј (Al 3 Li) precipitates. These states have trap-binding energies Յ25.2 kJ/mol. Under the charging conditions utilized, approximately 4 pct of the total (e.g., trapped and lattice) hydrogen content was associated with interstitial sites, consistent with the view that the intrinsic lattice solubility of hydrogen in aluminum is very low. In contrast, dislocations, grain boundaries, and T 1 (Al 2 CuLi) particles were found to be higher energy-trap states with trap-binding energies Ն31.7 kJ/mol. Approximately 78 pct of all absorbed hydrogen occupied these states. Moreover, greater than 13 pct of the available trap sites at grain boundaries were occupied. Such a high hydrogen coverage at grain-boundary sites supports the notion that hydrogen contributes to grain-boundary environmental cracking in Al-Li-CuZr alloys. Also, it points out the error in assuming that hydrogen cannot play a major role in cracking of Al-based alloys due to the low lattice solubility.

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“…Iino et al 20 have proposed a diffusion model, considering the situation of irreversible trapping. Leblond and Dubois 21 have also considered the combined effect of reversible and irreversible trapping effect, but only for low fractional occupancy of reversible trapping sites.…”

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confidence: 99%

Determination of Hydrogen Diffusion Parameters of Ferritic Steel from Electrochemical Permeation Measurement under Tensile Loads

Kim

Yun

Jung

2014

J. Electrochem. Soc.

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The hydrogen permeation experiment, performed with a stepwise permeation sequence involving "1 st permeation-desorption-2 nd permeation under loading, demonstrates that fine blister cracks are frequently observed on the steel surface in hydrogen charging side after the 2 nd permeation under the load over 95% of yield strength of the steel. To accommodate the experimental phenomena under the loading conditions, a numerical model is developed for determination of hydrogen diffusion parameters of the sour-resistant ferritic steel evaluated under tensile stress in plastic ranges. To solve the modified diffusion equation, a numerical finite difference method (FDM) is employed. The diffusion parameters determined by curve-fitting with the newly proposed diffusion equation indicates that, with the transition of mechanical domain from local-plasticity to generalized-plasticity, a big increase in the crack formation rate and hydrogen capture rate per irreversible trap are observed. It suggests that the transition probability for hydrogen transport from interstitial lattice site to irreversible trap site increases with the stress level. The high-strength ferritic steels used in the petrochemical industry suffer frequently from hydrogen assisted cracking (HAC) problem when they are used in a sour environment containing H 2 S. 1-3 Atomic hydrogens which result from the reduction of H + ions dissociated from H 2 S become the hydrogen molecule by the recombination reaction (H + H → H 2 ). Since H 2 S dissolved in aqueous environment suppresses this recombination reaction, the hydrogen atoms are easily adsorbed on the steel surface and diffuse into the steel matrix.4,5 The hydrogen atoms absorbed in the steel are reversibly or irreversibly trapped at various metallurgical defects in the steel, often resulting in the HAC failure. 2,6 With the depletion of high quality oil and gas, the HAC failure may become serious engineering problem for the highstrength steel pipes transporting and/or processing the low quality oil and gas containing a large amount of H 2 S.The HAC problem can be classified into two categories depending on the source of hydrogen and stress level; one is hydrogen induced cracking (HIC) occurring under no applied stress 2,6 and the other is sulphide stress cracking (SSC) occurring under applied tensile stress or residual stress. 7,8 In order to understand clearly HAC failure of the steels, the combined effect of hydrogen and applied stress should be evaluated together. A number of considerable efforts have been directed to evaluate the influence of applied tensile stress on the hydrogen diffusion behavior in the steel employing the electrochemical permeation technique.9-12 It has been generally accepted that the applied tensile stress in elastic range has no significant effect on the hydrogen diffusivity but increases the steady-state permeation flux due to the elastically expanded lattice. 10,12,13 On the other hand, a significant decrease in the permeation current has been observed in body centered cubic (BCC...

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A more generalized analysis of hydrogen trapping

Cited by 90 publications

References 6 publications

Modeling Thermal Desorption Analysis of Hydrogen in Steel

Modeling Thermal Desorption Analysis of Hydrogen in Steel

The identification of hydrogen trapping states in an Al-Li-Cu-Zr alloy using thermal desorption spectroscopy

Determination of Hydrogen Diffusion Parameters of Ferritic Steel from Electrochemical Permeation Measurement under Tensile Loads

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