Hydrogen detrapping from grain boundaries and dislocations in high purity iron

Ono, Kanji; Meshii, M.

doi:10.1016/0956-7151(92)90436-i

Cited by 167 publications

(84 citation statements)

References 17 publications

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“…Though the calculated trap energy of 47 kJ/mol at the coherent interface between strained ferrite and unstrained cementite does not directly correspond to the trap energy at the real coherent interface, the activation energy of 20-46 kJ/mol for the low temperature peak of TDS for pearlite estimated by Takai and Watanuki is lower than the reported trap energy of 49 kJ/mol 16) and 59 kJ/mol 17) at the grain boundary.…”

Section: Discussioncontrasting

confidence: 42%

Ab-initio Investigation of Hydrogen Trap State by Cementite in bcc-Fe

Kawakami

Matsumiya

2013

ISIJ Int.

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Hydrogen trap state by cementite in ferrite was investigated by ab-initio calculations. The calculated trap energy at cementite interstitial was 33 kJ/mol and that at the interface of cementite/ferrite was 39 kJ/mol. The calculated activation energy of the migration over the stable interstitial sites is 55 kJ/mol. Considering calculated zero point vibration energy, the trap energy at cementite interstitial becomes 41 kJ/mol and the activation energy becomes at least 59 kJ/mol. The low temperature peak at about 400 K in Thermal Desorption Spectrum (TDS) of cementite reported by other researchers is considered to correspond to the trap site at the cementite/ferrite interface. Since the interstitial trap site in cementite is not effective because of the high diffusion barrier at low temperature, the higher temperature peak at about 500 K in the TDS is considered to correspond to the migration energy from the defects such as grain boundaries in cementite introduced by deformation.

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Section: Discussioncontrasting

confidence: 42%

Ab-initio Investigation of Hydrogen Trap State by Cementite in bcc-Fe

Kawakami

Matsumiya

2013

ISIJ Int.

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“…One is the thermal detrapping of hydrogen from strongly trapped defects, 10,11) and the other is the diffusion of solute hydrogen interacting with weakly trapped hydrogen. 12) For the desorption from "strong, irreversible traps," two competing processes upon heating, i.e., an increasing thermal detrapping rate and an associated decrease in the hydrogen occupation in traps, give rise to a desorption-rate peak. The peak temperature T c is given as, 10) ...................... (1) where E a is the activation energy of detrapping, f is the linear heating rate, A is a constant and R is the gas constant.…”

Section: ϫ5mentioning

confidence: 99%

“…Recently, however, substantial progress has been made in the visualization of hydrogen trapping sites [6][7][8][9] and in the analysis of trapped states by means of thermal desorption analysis (TDA) of hydrogen. [10][11][12] While visualization techniques give direct information about the local distribution of hydrogen, TDA is useful for a quantitative examination of the trapped state as well as the hydrogen content.…”

Section: ϫ5mentioning

confidence: 99%

Simulation of Hydrogen Thermal Desorption under Reversible Trapping by Lattice Defects

Yamaguchi

Nagumo

2003

ISIJ International

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The hydrogen thermal desorption of a martensitic steel has been simulated assuming lattice hydrogen diffusion under a local equilibrium with reversibly trapped hydrogen as the rate-determining process. The calculated desorption curves reproduced the observed shift of the peak temperature associated with the specimen thickness and the heating rate. The calculation method involves a combination of a defect density and a hydrogen/defect binding energy as parameters. The dependence of the peak temperature on the defect density and the binding energy has been quantitatively shown. Assignment of the lattice defect relevant to the desorption curves is discussed. A calculation that took into account the increase in the defect density yielded results consistent with the observed change in the desorption curves associated with plastic strain.KEY WORDS: thermal desorption analysis; hydrogen diffusion; lattice defect; hydrogen trap; hydrogen embrittlement.

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“…86) On the other hand, when trapping is reversible to solid solution, i.e., for weak traps, a peak appears as the result of the competition between the decrease in the total hydrogen content in the specimen and the increase in the detrapping rate upon heating. 87) The desorption rate of hydrogen from a finite-size specimen was calculated by using the diffusion equation with the diffusion constant given in Eq. (8).…”

Section: Trapped Hydrogenmentioning

confidence: 99%

Advances in Physical Metallurgy and Processing of Steels. Function of Hydrogen in Embrittlement of High-strength Steels.

Nagumo

2001

ISIJ International

236

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Various models so far proposed for the mechanism of hydrogen embrittlement (HE) of steels are critically reviewed with respect to the manifestation of hydrogen in the fracture process. Recent studies that elucidate the hydrogen states and their relevance to HE are discussed. Particular attention is paid to the role of deformation-induced defects that interact with hydrogen. A model is proposed in which increased vacancy density and agglomeration lead to the promotion of failure. The model ascribes HE to the context of ductile fracture in which vacancies play the primary role.KEY WORDS: hydrogen embrittlement; fracture; lattice defect; fractography; thermal desorption analysis; high-strength steel. Fig. 1. Outline of the proposed mechanisms of HE due to hydrogen states in materials.

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Hydrogen detrapping from grain boundaries and dislocations in high purity iron

Cited by 167 publications

References 17 publications

Ab-initio Investigation of Hydrogen Trap State by Cementite in bcc-Fe

Ab-initio Investigation of Hydrogen Trap State by Cementite in bcc-Fe

Simulation of Hydrogen Thermal Desorption under Reversible Trapping by Lattice Defects

Advances in Physical Metallurgy and Processing of Steels. Function of Hydrogen in Embrittlement of High-strength Steels.

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