Elucidating the variables affecting accelerated fatigue crack growth of steels in hydrogen gas with low oxygen concentrations

Somerday, Brian P.; Sofronis, Petros; Nibur, Kevin A.; Marchi, Chris San; Kirchheim, R.

doi:10.1016/j.actamat.2013.07.001

Cited by 144 publications

(83 citation statements)

References 21 publications

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“…Fraction of intergranular fracture in Stage I increased at increasing hydrogen pressures. A similar transition from IG to QC fracturing between Stages I and II has also been reported in some pipeline steels [17,18] tested in hydrogen gas.…”

Section: Fracture Surface Morphologymentioning

confidence: 61%

Hydrogen-assisted fatigue crack propagation in a pure BCC iron. Part II: Accelerated regime manifested by quasi-cleavage fracture at relatively high stress intensity range values

et al. 2018

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Abstract. Hydrogen effect on fatigue performance at relatively high values of stress intensity factor range, ΔK, of pure BCC iron has been studied with a combination of various electron microscopy techniques. Hydrogen-assisted fatigue crack growth rate is manifested by a change of fracture features at the fracture surface from ductile transgranular in air to quasi-cleavage in hydrogen gas. Grain reference orientation deviation (GROD) analysis has shown a dramatic suppression of plastic deformation around the crack wake in samples fatigued in hydrogen. These results were verified by preparing site-specific specimens from different fracture features by using Focused Ion Beam (FIB) technique and observing them with Transmission Electron Microscope (TEM). The FIB lamella taken from the sample fatigued in air was decorated with dislocation cell structure indicating high amount of plasticity, while the lamella taken from the quasi-cleavage surface of the sample fatigued in hydrogen revealed a distribution of dislocation tangles which corresponds to smaller plastic strain amplitude involved at the point of fracture. These results show that a combination of critical hydrogen concentration and critical stress during fatigue crack growth at high ΔK values triggers cleavage-like fracture due to reduction of cohesive force between matrix atoms.

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Section: Fracture Surface Morphologymentioning

confidence: 61%

Hydrogen-assisted fatigue crack propagation in a pure BCC iron. Part II: Accelerated regime manifested by quasi-cleavage fracture at relatively high stress intensity range values

et al. 2018

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“…Hydrogen embrittlement or hydrogen-induced crack initiation is ubiquitous in many semiconducting [58,59] and metallic alloys including steels and Al-and Ni-based systems [60][61][62][63][64]. There is evidence that the severity of the embrittlement depends on the presence of a native oxide [15], through which hydrogen has to pass. However, there is a paucity of studying the role of the native oxides that grow on these alloys in regulating the entry of hydrogen.…”

Section: Discussionmentioning

confidence: 99%

“…All refractory metallic alloys develop a protective corrosion layer at their surface, such as Cr-, Fe-, and Ni-oxide layers on steels and Ni-based alloys. There is evidence that these surface oxide layers affect the penetration of hydrogen into the underlying metal [15], and as such we propose that they can be engineered by doping to resist hydrogen entry. By computing the formation free energies of all hydrogen defects in these oxides, it is possible to determine general hydrogen-solubility curves as a function of μ e in these oxides.…”

Section: Introductionmentioning

confidence: 99%

Doping in the Valley of Hydrogen Solubility: A Route to Designing Hydrogen-Resistant Zirconium Alloys

2016

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Hydrogen pickup and embrittlement pose a challenging safety limit for structural alloys used in a wide range of infrastructure applications, including zirconium alloys in nuclear reactors. Previous experimental observations guide the empirical design of hydrogen-resistant zirconium alloys, but the underlying mechanisms remain undecipherable. Here, we assess two critical prongs of hydrogen pickup through the ZrO 2 passive film that serves as a surface barrier of zirconium alloys; the solubility of hydrogen in it-a detrimental process-and the ease of H 2 gas evolution from its surface-a desirable process. By combining statistical thermodynamics and density-functional-theory calculations, we show that hydrogen solubility in ZrO 2 exhibits a valley shape as a function of the chemical potential of electrons, μ e . Here, μ e , which is tunable by doping, serves as a physical descriptor of hydrogen resistance based on the electronic structure of ZrO 2 . For designing zirconium alloys resistant against hydrogen pickup, we target either a dopant that thermodynamically minimizes the solubility of hydrogen in ZrO 2 at the bottom of this valley (such as Cr) or a dopant that maximizes μ e and kinetically accelerates proton reduction and H 2 evolution at the surface of ZrO 2 (such as Nb, Ta, Mo, W, or P). Maximizing μ e also promotes the predomination of a less-mobile form of hydrogen defect, which can reduce the flux of hydrogen uptake. The analysis presented here for the case of ZrO 2 passive film on Zr alloys serves as a broadly applicable and physically informed framework to uncover doping strategies to mitigate hydrogen embrittlement also in other alloys, such as austenitic steels or nickel alloys, which absorb hydrogen through their surface oxide films.

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“…For the storage and transportation of compressed gaseous hydrogen in the forthcoming hydrogen energybased society, hydrogen-assisted fatigue crack growth (HAFCG) in structural steels is of significant concern with regards to the safe design of high-pressure components such as pressure vessels or pipelines [1,2]. For elucidating the detailed fatigue crack growth (FCG) behaviour of iron and steels with ferritic, i.e.…”

Section: Introductionmentioning

confidence: 99%

Hydrogen-assisted fatigue crack propagation in a pure BCC iron. Part I: Intergranular crack propagation at relatively low stress intensities

et al. 2018

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Abstract. The role of hydrogen on intergranular (IG) fracture in hydrogen-assisted fatigue crack growth (HAFCG) of a pure iron at low stress intensity was discussed in terms of the microscopic deformation structures near crack propagation paths. The main cause of IG fracture was assumed to be the hydrogen-enhanced dislocation structure evolution and subsequent microvoids formation along the grain boundaries. Additionally, the impact of such IG cracking on the macroscopic FCG rate was evaluated according to the dependency of IG fracture propensity on the hydrogen gas pressure. It was first demonstrated that the increased hydrogen pressure results in the larger area fraction of IG and corresponding faster FCG rate. Moreover, gaseous hydrogen environment also had a positive influence on the FCG rate due to the absence of oxygen and water vapor. The macroscopic crack propagation rate was controlled by the competition process of said positive and negative effects.

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Elucidating the variables affecting accelerated fatigue crack growth of steels in hydrogen gas with low oxygen concentrations

Cited by 144 publications

References 21 publications

Hydrogen-assisted fatigue crack propagation in a pure BCC iron. Part II: Accelerated regime manifested by quasi-cleavage fracture at relatively high stress intensity range values

Hydrogen-assisted fatigue crack propagation in a pure BCC iron. Part II: Accelerated regime manifested by quasi-cleavage fracture at relatively high stress intensity range values

Doping in the Valley of Hydrogen Solubility: A Route to Designing Hydrogen-Resistant Zirconium Alloys

Hydrogen-assisted fatigue crack propagation in a pure BCC iron. Part I: Intergranular crack propagation at relatively low stress intensities

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