Hydrogen solubility, diffusivity and trapping in a tempered Fe–C–Cr martensitic steel under various mechanical stress states

Frappart, S.; Feaugas, X.; Creus, J.; Thébault, Florian; Delattre, Laurent; Marchebois, Herve

doi:10.1016/j.msea.2011.11.084

Cited by 87 publications

(45 citation statements)

References 79 publications

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“…[14][15][16] When the stress level becomes close to the yield strength (YS), however, the effect of tensile stress on the hydrogen permeation does not follow the general effect of elastic stress which induces the increase in permeation flux due to the lattice expansion, but often results decrease in the permeation flux. 17 A slight decrease in the apparent diffusivity of hydrogen is also observed. Furthermore, surface blisters and internal cracks acting as hydrogen trapping sites are newly created during the permeation test.…”

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confidence: 91%

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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mentioning

confidence: 91%

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 more hydrogen traps there are, it is expected that the welding zone present a lower hydrogen diffusivity because the traps are filled first. 15) From this figure and Fig. 7, it can be observed that the hydrogen tends to concentrate on areas of higher hardness.…”

Section: Resultsmentioning

confidence: 73%

“…In the CGHAZ microhardness is higher than that of the BM due to the formation of martensite, and in the FZ microhardness decreased due to the formation of bainite. Increasing the hardness of the welding zone, is related to the increase in yield stress and the generation of residual stresses by thermal gradients and phase transformations (high chemical activity zone), and these in turn are related to increased susceptibility to HIC, 6,15,29,30) so it would expect that the CGHAZ to be the subzone more susceptible of both steels, particularly the subzone of the M1 steel. During the preparation of the solution for silver decoration, the most likely reactions that present are: 25) AgNO KCN AgCN KNO Fig.…”

Section: Resultsmentioning

confidence: 99%

“…The problem with hydrogen is its low solubility in the lattice, its high power to be adsorbed, absorbed and diffused and its ability to localize at internal sites such as voids, precipitates, inclusions, grain boundaries and regions with high stresses; 5,14,15) as well as its ability to react with certain elements to form hydrides. The driving force for hydrogen diffusivity is a difference of activities presented as a concentration gradient, stress gradient, electrical gradient and temperature gradient.…”

Section: Hydrogen Diffusivity In the Welding Zone Of Two High Strengtmentioning

confidence: 99%

“…23) In short, hydrogen diffusion in steel is influenced by two factors: a) a difference of chemical activities and b) hydrogen traps (grain boundaries, solute atoms, voids, inclusions, precipitates, phases and dislocations). 12,15,24) Although residual stress and yield stress are the important parameters to produce HIC, for example, it has been shown that with increased yield stress, increases the accumulation of hydrogen in the area of crack tip corresponding to the zone where is located the maximum triaxial tensile stress; 5,6) all mechanisms that attempt to explain the damage caused by hydrogen, agree that for this phenomenon to exist requires that the hydrogen diffuses towards a high activity zone. Thus, to study the susceptibility of a steel or a microstructure to HIC, hydrogen diffusivity should be determined.…”

Section: Hydrogen Diffusivity In the Welding Zone Of Two High Strengtmentioning

confidence: 99%

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Hydrogen Diffusivity in the Welding Zone of Two High Strength Experimental Microalloyed Steels

et al. 2015

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Using permeation tests, determination of hydrogen trapping and microhardness measurements, the effect of the microstructure on the hydrogen diffusivity was analyzed in the welding zone of two highstrength experimental microalloyed steels called M1 steel, with a martensite and bainite microstructure and M2 steel with a quasi-polygonal ferrite (QPF), acicular ferrite (AF) and martensite-austenite (M/A) microstructure. Determination of the diffusivity was performed using electrochemical permeation tests, and hydrogen traps were determined with the silver decoration technique.One-pass welds without filler material were simulated with the Gas Tungsteng Arc Welding (GTAW) process, and samples of the welding zone were collected: base material (BM), heat affected zone (HAZ) and fusion zone (FZ). A Devanathan and Stachurski type electrochemical cell was constructed to conduct permeation tests. From the microstructural analysis, the permeation testing and silver decoration, it was observed that the hydrogen diffusivity decreases with the increase in traps, promotion of the formation of the M/A microconstituent and AF and the reduction of martensite and bainite microconstituents. The lower diffusivity of all zones of both steels is presented by the BM of M2 steel, which is associated with a QPF, AF and M/A microstructure and low microhardness. The highest relative amount of traps are in the coarse grained heat affected zone (CGHAZ) of both steels, however because these are reversible traps, these subzones could be the most susceptible to hydrogen induced cracking (HIC).

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Hydrogen‐induced Damage ( HTHA , Embrittlement and Blistering)

2024

Hydrogen Energy

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Hydrogen solubility, diffusivity and trapping in a tempered Fe–C–Cr martensitic steel under various mechanical stress states

Cited by 87 publications

References 79 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 Diffusivity in the Welding Zone of Two High Strength Experimental Microalloyed Steels

Hydrogen‐induced Damage ( HTHA , Embrittlement and Blistering)

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