Hydrogen transport through annealed and deformed armco iron

Kumnick, A. J.; Johnson, H. H.

doi:10.1007/bf02644334

Cited by 166 publications

(52 citation statements)

References 16 publications

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“…Based on a number of permeation test results reported by numerous researchers, it can be known that the shape of the 1 st permeation transient can be greatly dependent upon steel type, chemical composition, level of plastic deformation and microstructure. It has been reported that the break through time in the 1 st permeation of stainless steels or high alloy steels (stainless steel, 22,30,31,32 Cr-Mo steel, 9,33 high carbon steel, 17,34 TRIP steel 16 ) is comparatively longer than that of low alloy low carbon steels (pure iron, 10,27,35,36 low carbon ferritic steel 6,34,37 HIC fracture surface of the tested steel, which was obtained by a specially designed mechanical process after crack analysis by using ultrasonic detector. curves provides an approximate estimation of irreversible trapping phenomenon.…”

Section: Resultsmentioning

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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Section: Resultsmentioning

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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“…Namboodhiri and Nanis and others also (42) (26), (43), (53) observed the concentration dependence of effective diffusivity.…”

Section: Evaluation Of Analyses Of Absorption and Evolution Transimentioning

confidence: 77%

“…It is possib le to correlat e these 'results with the gas-phas e (53) charging carried out by Kumnick , based on the steady state properti es of the hydrogen transpor t, i.e., figs. 10 and 12 for specimen with Pd films on both sides.…”

Section: Correlat Ion Between Gas-phas E and Electroc Hemical Charmentioning

confidence: 86%

“…The straight line is the least square fit of gas-phas e charging data For any given value of Jac L for 2-side specimens in (53) fig. 12, it is always possible to find an effectiv e pressure for the current density which gives this value of Joc L. Since the correspo nding effectiv e pressure can be quite high, up to 30…”

Section: Correlat Ion Between Gas-phas E and Electroc Hemical Charmentioning

confidence: 99%

“…The best way to test the agreement of boundary conditions -between the experimental situation and the theoretical consideration is to compare both the normalized absorption and evolution transients between gas-phase and electrochemical chargings the normalized evolution transient of electrochemical charging falls off much slower than that of gas-phase charging (53) In gas .= phase charging, the boundary condition on the entrance surface, when hydrogen gas is removed away by pure high-speed helium gas, is very close to zero. Its evolution transient falls off rapidly as expected from the theoretical for this anomaly, since we have volume controlled process.…”

Section: Evaluation Of Analyses Of Absorption and Evolution Transimentioning

confidence: 99%

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Hydrogen permeation through annealed zone-refined iron by using electrochemical charging at room temperature

Shih¹

1975

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Diffusion of Tritium in Cold‐Worked Palladium

Sicking

Glugla

Huber

1983

Ber Bunsenges Phys Chem

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The mobility of hydrogen in cold-rolled palladium specimens of different degree of plastic deformation was measured by employing the tritium tracer method. -In one set of experiments the temperature dependence of the diffusivity was determined at very low hydrogen to metal ratios below aboutIn another set of experiments the influence of precharged hydrogen on the tritium mobility was investigated at constant temperature. -The diffusion of tritium as a tracer in presence of hydrogen and within an imperfect lattice is treated on the assumption of local isotope distribution equilibrium between traps and interstitial sites. A trap binding energy of about 18 kJmol-' is obtained. -By means of a selfconsistent evaluation of the experimental data also the trap binding entropy, the concentration of traps, and the separation factor of the isotope distribution equilibrium is determined. -It is found that tritium is enriched in interstitial positions. The concentration of traps is doubled on going from 30% to 50% of deformation. The localized vibrations of tritium in trap sites are found to be distinctly softer than in interstitial positionb. -We suggest dislocation cores and sites close to dislocation cores as operating traps. The interaction energy between hydrogen and dislocation traps is discussed in connection with the misfit energy of hydrogen in metals.

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Hydrogen transport through annealed and deformed armco iron

Cited by 166 publications

References 16 publications

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

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

Hydrogen permeation through annealed zone-refined iron by using electrochemical charging at room temperature

Diffusion of Tritium in Cold‐Worked Palladium

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