Hydrogen-Trapping Mechanisms in Nanostructured Steels

Szost, Blanka A.; Vegter, R. H.; Rivera-Dı́az-del-Castillo, P.E.J.

doi:10.1007/s11661-013-1795-7

Cited by 73 publications

(32 citation statements)

References 33 publications

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“…Residual hydrogen contents measured using the extraction melting technique 23 also strongly support our discussion. Four samples (4 Â 8 Â 3 mm) of each type were tested using LECO Hydrogen Determinator (RH 600, range 0.01-5000 ppm).…”

Section: 7-10supporting

confidence: 80%

Thermal outgassing rates of low-carbon steels

Park¹,

Ha²,

Cho

2015

Journal of Vacuum Science &Amp; Technology A: Vacuum, Surfaces, and Films

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Outgassing rates of three low-carbon steels were measured using rate-of-rise and throughput methods. Outgassing rates of water vapor during pump-down were higher than those of stainless steels, probably due to the nature of native surface oxide layer. However, hydrogen outgassing rates without a high temperature pretreatment were as low as (1–4) × 10−10 Pa m3 s−1 m−2, which is much lower than that of untreated stainless steels. No dramatic reduction was observed in H2 outgassing after vacuum annealing at 850 °C for 12 h, suggesting that the low-carbon steels had been fully degassed during the steelmaking processes. This may be due to the use of the Ruhrstahl-Hausen vacuum process during steel refining instead of an older process, such as argon-oxygen decarburization. The extremely low H2 outgassing rate from low-carbon steels makes them applicable for use in ultrahigh vacuum or even extreme high vacuum applications, particularly where magnetic field shielding is needed.

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Section: 7-10supporting

confidence: 80%

Thermal outgassing rates of low-carbon steels

Park¹,

Ha²,

Cho

2015

Journal of Vacuum Science &Amp; Technology A: Vacuum, Surfaces, and Films

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“…[8][9][10][11] Among these explanations, there is consensus in that mobile hydrogen causes degradation in steels. 12) Therefore, it is appropriate for reducing the HE susceptibility by preventing the ingress of hydrogen or immobilizing free hydrogen by trapping them in certain sites. [13][14][15] In general, trapping sites for hydrogen are separated by reversible traps or irreversible traps with a critical binding energy value, which can be acquired by thermal desorption or permeation analysis.…”

Section: Introductionmentioning

confidence: 99%

“…[13][14][15] In general, trapping sites for hydrogen are separated by reversible traps or irreversible traps with a critical binding energy value, which can be acquired by thermal desorption or permeation analysis. 16) Reversible traps include dislocations, microvoids and coherent precipitates/interfaces which can immobilize and release hydrogen at low temperatures normally below 573 K. 12) In contrary, irreversible trap absorbs hydrogen and prevent it from escaping until it reaches even higher temperature. For example, H-MnS has a binding energy 72.3 kJ/mol; 17) H-Al 2 O 3 has a binding energy 71.4 kJ/mol.…”

Section: Introductionmentioning

confidence: 99%

Hydrogen Traps and Hydrogen Induced Cracking in 20CrMo Steel

Zhu

Yao

et al. 2017

ISIJ Int.

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The hydrogen trapping sites of commercial 20CrMo steel samples with electrochemically charged hydrogen were characterized by thermoelectric power (TEP) and scanning Kelvin probe force microscope (SKPFM). A surface potential drop of about 190 mV was found for the globular MnS inclusion and 150 mV for the elongated one due to the hydrogen absorption of MnS inclusions. Similar to thermal desorption measurement, TEP is a potential method in analyzing hydrogen traps of solid solution, dislocations and irreversible traps. The fracture morphology and hydrogen induced cracking can be explained by combined hydrogen embrittlement mechanisms. Although hydrogen induced cracks are found to initiate at the elongated inclusions, only longitudinal cracks were observed in this study which is not detrimental to the embrittlement.

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“…Here, the coupling is indirect, and far exceeds the range of the individual interactions between pairs of atoms. The need to represent the large stress gradients associated with, for example, grains in nanostructured metals, 4 dislocation cores, 5 or crack tips 6 and their tight dynamical coupling with local chemistry necessitates the description of bond breaking reactions in systems containing 10 5 -10 7 atoms. Electrostatic coupling, where long-range Coulomb interactions are insufficiently screened to be neglected, is common in biochemical systems 3,7 but can also be important for polar solid-state materials such as silica and other oxides.…”

Section: Introductionmentioning

confidence: 99%

Accuracy of buffered-force QM/MM simulations of silica

Peguiron

Ciacchi

Vita

et al. 2015

The Journal of Chemical Physics

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We report comparisons between energy-based quantum mechanics/molecular mechanics (QM/MM) and buffered force-based QM/MM simulations in silica. Local quantities-such as density of states, charges, forces, and geometries-calculated with both QM/MM approaches are compared to the results of full QM simulations. We find the length scale over which forces computed using a finite QM region converge to reference values obtained in full quantum-mechanical calculations is ∼10 Å rather than the ∼5 Å previously reported for covalent materials such as silicon. Electrostatic embedding of the QM region in the surrounding classical point charges gives only a minor contribution to the force convergence. While the energy-based approach provides accurate results in geometry optimizations of point defects, we find that the removal of large force errors at the QM/MM boundary provided by the buffered force-based scheme is necessary for accurate constrained geometry optimizations where Si-O bonds are elongated and for finite-temperature molecular dynamics simulations of crack propagation. Moreover, the buffered approach allows for more flexibility, since special-purpose QM/MM coupling terms that link QM and MM atoms are not required and the region that is treated at the QM level can be adaptively redefined during the course of a dynamical simulation. C 2015 AIP Publishing LLC. [http://dx

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Hydrogen-Trapping Mechanisms in Nanostructured Steels

Cited by 73 publications

References 33 publications

Thermal outgassing rates of low-carbon steels

Thermal outgassing rates of low-carbon steels

Hydrogen Traps and Hydrogen Induced Cracking in 20CrMo Steel

Accuracy of buffered-force QM/MM simulations of silica

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