A Concept for Development of Hydrogen-Resistant Austenitic Steels

Volume 6B: Materials and Fabrication ◽

10.1115/pvp2013-97011 ◽

2013 ◽

Author(s):

Valentin Gavriljuk ◽

Bela Shanina ◽

Vladyslav Shyvanyuk ◽

Sergey Teus

Keyword(s):

Solid Solution ◽

Hydrogen Embrittlement ◽

Solid Solutions ◽

Austenitic Steels ◽

Hydrogen Degradation ◽

Hydrogen Atoms ◽

Free Electrons ◽

Physical Reason ◽

Hydrogen Resistance

Austenitic steels represent a promising class of engineering materials for hydrogen use in vehicles, e.g. for tanks and pipelines. This topic is analyzed in terms of the effect of alloying elements on the interatomic bonds in the solid solutions and, consequently, on the interaction between hydrogen atoms and dislocations and hydrogen embrittlement, HE. The effect of Cr, Ni, Mn, Mo, Si, Al, Cu, C, N was studied. It is shown that the physical reason for HE amounts to the hydrogen-caused increase in the concentration of free electrons in the austenitic solid solution. For this reason, the alloying with elements decreasing the concentration of free electrons is expected to improve resistance of austenitic steels to HE. Alloying with Cr, Mn, Mo and Si is shown to be useful, whereas Cu, Al, Ni, N assist hydrogen degradation. The role of Ni amounts only to stabilization of the fcc austenitic lattice and its absence or the decrease of its content in steel is desirable. Based on the obtained results, recommendations are made for design of austenitic steels with increased hydrogen resistance.

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Hydrogen embrittlement of austenitic steels: electron approach

Corrosion Reviews ◽

10.1515/corrrev-2013-0024 ◽

2013 ◽

Vol 31 (2) ◽

pp. 33-50 ◽

Cited By ~ 11

Author(s):

Valentin G. Gavriljuk ◽

Bela D. Shanina ◽

Vladyslav N. Shyvanyuk ◽

Sergey M. Teus

Keyword(s):

Hydrogen Embrittlement ◽

Experimental Studies ◽

Experimental Tests ◽

Elastic Interaction ◽

Plasticity Theory ◽

Electron Structure ◽

Austenitic Steels ◽

Free Electrons ◽

Steel Alloying ◽

Hydrogen Resistance

AbstractA review of available hypotheses for hydrogen embrittlement (HE) in its relation to austenitic steels is presented. It is shown that the hydrogen-enhanced localized plasticity theory adequately describes the features of HE. Nevertheless, being developed within the frame of continuum mechanics, it overestimates the hydrogen-induced shielding of the elastic interaction between dislocations and does not take into account the hydrogen-induced change in the electron structure of austenitic steels. Ab initio calculations and experimental studies of the electron structure show that the hydrogen in austenitic steels increases the concentration of free electrons, nf, and the interpretation of available experimental data shows that when designing steel, alloying the steel with elements that decrease nf improves hydrogen resistance. Experimental tests are carried out, and their results are discussed. Based on the hydrogen-increased concentration of thermodynamic equilibrium vacancies in the interstitial solid solutions, a new model for hydrogen-induced shear localization is proposed.

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Mechanism of Hydrogen Embrittlement of Austenitic Steels

Materials Science Forum ◽

10.4028/www.scientific.net/msf.539-543.4249 ◽

2007 ◽

Vol 539-543 ◽

pp. 4249-4254 ◽

Cited By ~ 4

Author(s):

V. Shivanyuk ◽

Valentin G. Gavriljuk ◽

Jacques Foct

Keyword(s):

Hydrogen Embrittlement ◽

Line Tension ◽

Austenitic Steels ◽

Hydrogen Atoms ◽

Conduction Electrons ◽

Metallic Character ◽

Spin Resonance ◽

Localization Of Plastic Deformation ◽

Dislocation Sources ◽

Strain Dependent

Three main hypotheses of hydrogen embrittlement (HE) of austenitic steels are discussed based on the studies of the interatomic interactions, hydrogen-induced phase transformations and dislocations properties. Measurements of electron spin resonance and ab initio calculations of the electron structure witness that the concentration of conduction electrons increases due to hydrogen, which enhances the metallic character of interatomic bonds. The hypothesis of brittle hydrogen-induced phases is disproved by the studies of the silicon-alloyed steels: the silicon-caused increase in the fraction of the εH martensite is accompanied by the decrease of HE. Studies of strain-dependent internal friction have shown the hydrogen-caused decrease in the start stress of microplasticity and increase in the velocity of dislocations in accordance with HELP hypothesis. A mechanism of HELP is proposed based on the hydrogencaused enhancement of the metallic character of interatomic bonds, which results in the local decrease of the shear modulus within the hydrogen atmospheres round the dislocations. As consequence, the line tension of the dislocations followed by the hydrogen atoms decreases, which finds its expression in the early start of dislocation sources, decreased distance between dislocations in the pile-ups and increased velocity of dislocations. A mechanism of localization of plastic deformation is proposed based on the observations of the hydrogen-enhanced concentration of equilibrium vacancies.

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The Electrical Resistance of Dilute Solid Solutions

Mathematical Proceedings of the Cambridge Philosophical Society ◽

10.1017/s0305004100001845 ◽

1936 ◽

Vol 32 (2) ◽

pp. 281-290 ◽

Cited By ~ 250

Author(s):

N. F. Mott

Keyword(s):

Solid Solution ◽

Electrical Conductivity ◽

Solid Solutions ◽

Electrical Resistance ◽

Unit Volume ◽

Effective Number ◽

Free Electrons ◽

Mechanical Explanation ◽

Image Position ◽

Matthiessen's Rule

1. As is well known, the electrical resistance of a metal is very greatly in-creased by the addition of a second metal with which it forms a solid solution. The increase Δρ in the resistivity due to the addition of a small percentage of the second metal is in general independent of the temperature (Matthiessen's rule), though there are oertain exceptions (e.g. Cr in Au). The quaritum-mechanical explanation of both these facts was first given by Nordheim, and may be expressed as follows: the electrical conductivity of any metal may be written in the formwhere τ is the “time of relaxation”, equal to half the time between collisions, and N is the effective number of free electrons per unit volume: hence, for the resistivity, we have

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Fatigue of Austenitic High Interstitial Steels - The Role of N and C

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.891-892.403 ◽

2014 ◽

Vol 891-892 ◽

pp. 403-409 ◽

Cited By ~ 5

Author(s):

Michael Schymura ◽

Alfons Fischer

Keyword(s):

Endurance Limit ◽

Cold Working ◽

Near Field ◽

Fatigue Tests ◽

Austenitic Steels ◽

High Nitrogen ◽

Free Electrons ◽

Microstructural Characteristics ◽

C And N

In order to increase the strength and maintain the ductility of austenitic steels high Nitrogen austenitic steels (AHNS) emerged of which Ni was substituted by Mn so that up to 1 w% N could be alloyed and kept in solid solution. Cold working was added to gain strength values up to 3000 MPa. Still the endurance limit did not follow this trend. The low stacking fault energy was thought being the main reason for the solely planar slip but it became clear that other near-field effects might govern this behaviour as well. Thus the density of free electrons could be identified as being one for CrMn-steels being mainly influenced by the sum and the ratio of C and N. In order to investigate this strain-controlled fatigue tests are carried out. This contribution presents the results of strain-controlled fatigue tests and discusses them on the basis of SEM-EBSD and TEM investigations in relation to the microstructural characteristics.

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Role of the martensite transformation in hydrogen embrittlement of unstable austenitic steels

Soviet Materials Science ◽

10.1007/bf00726554 ◽

1986 ◽

Vol 21 (4) ◽

pp. 320-323 ◽

Cited By ~ 5

Author(s):

G. G. Maksimovich ◽

I. Yu. Tretyak ◽

L. M. Ivas'kevich ◽

T. V. Slipchenko

Keyword(s):

Hydrogen Embrittlement ◽

Martensite Transformation ◽

Austenitic Steels

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Hydrogen-induced γ→ɛ transformation and the role of ɛ-martensite in hydrogen embrittlement of austenitic steels

Materials Science and Engineering A ◽

10.1016/j.msea.2008.07.003 ◽

2008 ◽

Vol 497 (1-2) ◽

pp. 290-294 ◽

Cited By ~ 44

Author(s):

S.M. Teus ◽

V.N. Shyvanyuk ◽

V.G. Gavriljuk

Keyword(s):

Hydrogen Embrittlement ◽

Austenitic Steels

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Hydrogen Embrittlement and Improved Resistance of Al Addition in Twinning-Induced Plasticity Steel: First-Principles Study

Materials ◽

10.3390/ma12081341 ◽

2019 ◽

Vol 12 (8) ◽

pp. 1341

Author(s):

Lilin Lu ◽

Jiaqi Ni ◽

Zhixian Peng ◽

Haijun Zhang ◽

Jing Liu

Keyword(s):

Hydrogen Embrittlement ◽

Compressive Stress ◽

First Principles ◽

Binding Energies ◽

Austenitic Steels ◽

Hydrogen Atoms ◽

Young’S Moduli ◽

Site Preferences ◽

Work First ◽

Interstitial Hydrogen

Understanding the mechanism of hydrogen embrittlement (HE) of austenitic steels and developing an effective strategy to improve resistance to HE are of great concern but challenging. In this work, first-principles studies were performed to investigate the HE mechanism and the improved resistance of Al-containing austenite to HE. Our results demonstrate that interstitial hydrogen atoms have different site preferences in Al-free and Al-containing austenites. The calculated binding energies and diffusion barriers of interstitial hydrogen atoms in Al-containing austenite are remarkably higher than those in Al-free austenite, indicating that the presence of Al is more favorable for reducing hydrogen mobility. In Al-free austenite, interstitial hydrogen atoms caused a remarkable increase in lattice compressive stress and a distinct decrease in bulk, shear, and Young’s moduli. Whereas in Al-containing austenite, the lattice compressive stress and the mechanical deterioration induced by interstitial hydrogen atoms were effectively suppressed.

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Effect of γ-radiation on magneto-thermoelectric properties of the extruded samples of Bi85Sb15〈Te〉 solid solution

International Journal of Modern Physics B ◽

10.1142/s0217979221500995 ◽

2021 ◽

pp. 2150099

Author(s):

I. A. Abdullayeva ◽

G. D. Abdinova ◽

M. M. Tagiyev ◽

O. A. Samedov

Keyword(s):

Magnetic Field ◽

Solid Solution ◽

Electrical Conductivity ◽

Radiation Dose ◽

Seebeck Coefficient ◽

Free Electrons ◽

Γ Radiation ◽

Charged Carrier ◽

Different Doses

Extruded samples of [Formula: see text] solid solutions doped with 0.0005 at.% Te were obtained and the electrical conductivity [Formula: see text], thermoelectric power (Seebeck) [Formula: see text], Hall [Formula: see text] and thermal conductivity [Formula: see text] coefficients were investigated in the range [Formula: see text]–300 K samples and magnetic field strength up to [Formula: see text] A/m, as annealed after extrusion, non-irradiated with gamma-quanta and the same samples irradiated with gamma quanta at different doses. It was found that at low doses (1 Mrad) of irradiation, radiation defects (RDs) appear in the samples which play the role of donor centers, as a result of which the concentration of free electrons [Formula: see text], and, consequently the electrical conductivity [Formula: see text] increases, and the Seebeck coefficient [Formula: see text] decreases. These defects, scattering the current carriers, reduce their mobility [Formula: see text]. With an increase in the radiation dose, the concentration of defects also increases and free carriers are captured at the level of the RD. In this regard, the concentration of charged carrier defects [Formula: see text] and, consequently, [Formula: see text] of the sample decrease, while the Seebeck coefficient and mobility increase. The effect of a magnetic field on the electrical and thermal parameters of extruded solid solution samples also depends on the radiation dose in the sample.

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Cobalt Effect on Creep Behavior of Nickel Solid Solution Alloys

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100096990 ◽

1981 ◽

Vol 39 ◽

pp. 54-55

Author(s):

L. S. Lin ◽

C. C. Law ◽

M. J. Blackburn

Keyword(s):

Solid Solution ◽

Solid Solutions ◽

Thin Foil ◽

Weight Percent ◽

Cobalt Alloy ◽

Creep Tests ◽

Gamma Prime ◽

Nickel Base ◽

Cobalt Effect

To understand the role of cobalt in nickel-base superalloys, multicomponent nickel solid solutions with various amounts of cobalt were studied. Alloys A, B, C and D which contain cobalt at 30, 17, 8 and 0, respectively, and constant concentrations of Cr(25), Mo(5), Al(0.5), Ti(0.5), Nb(0.4), Hf(0.1), all in weight percent, were produced by casting. Compressive creep tests of these alloys were conducted at temperatures between 650°C and 810°C. Table 1 shows the minimum creep rates at 704°C at a stress of 120% of their respective yield strengths. It can be seen that the alloy without cobalt (Alloy D) creeps at a rate 20 times faster than Alloy A with 30 wt.% cobalt and the values for Alloys B and C with intermediate cobalt contents fall between Alloys A and D. Thin foil studies have revealed that the differences can be attributed, in part, to (i) change of stacking fault energy with cobalt, (ii) precipitation of fine gamma prime particles during creep.

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