The role of stress state on hydrogen cracking in Fe-Si single crystals

Chen, X.; Foecke, Timothy J.; Lii, Mirng-Ji; Katz, Y.; Gerberich, William W

doi:10.1016/0013-7944(90)90128-4

Cited by 49 publications

(7 citation statements)

References 35 publications

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“…[115] This result suggests that solute is not a trap off from the tip of a sharp crack. [101,102,103] For K ϭ 20 MPaΊm, this model predicted that H ϭ 22 GPa maximized state, as confirmed by the lack of low E B trapping in asquenched AERMET 100 with solute but without M 2 C preat 20 nm ahead of the tip. Hutchinson and others predicted stress elevation due to hardening by excess and geometricipitates.…”

Section: The H-uptake-capacity Dependence Ofsupporting

confidence: 60%

Internal hydrogen embrittlement of ultrahigh-strength AERMET 100 steel

Thomas

Scully

Gangloff

2003

Metall Mater Trans A

139

110

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Near-peak-aged AERMET 100 is susceptible to severe internal hydrogen embrittlement (IHE) at 23 ЊC, if a sufficient diffusible hydrogen content is present, compromising the high toughness of this ultrahigh-strength steel (UHSS). Evidence includes the threshold stress intensity for subcritical IHE (K TH ) as low as 10 pct of the plane-strain fracture toughness (K IC ) and a fracture-mode transition from microvoid coalescence to brittle transgranular (TG) cracking, apparently along martensite lath interfaces and cleavage planes. The K TH value decreases from a K IC value of 132 to 143 MPaΊm to 12 MPaΊm, and the amount of brittle TG fracture increases to nearly 100 pct as the concentration of diffusible H increases from essentially 0 to 8 wppm, with severe embrittlement in the 0 to 2 wppm H regime. The IHE is time dependent, as evidenced by increasing K TH values with increasing dK/dt and K-independent subcritical crack growth rates, and is attributed to diffusional H repartition from reversible trap sites to the stressed crack tip. The partition distance is ϳ1 m, consistent with the fine-scale microstructure of AERMET 100. The causes of the susceptibility of AERMET 100 to TG IHE are very high crack-tip stresses and a reservoir of mobile H trapped reversibly at (Fe,Cr,Mo) 2 C precipitates. These factors enable repartition of H to misoriented martensite lath interfaces and interstitial sites near cleavage planes, with each prone to decohesion along a connected path. Predissolved H also reduces the ductile fracture toughness of AERMET 100 at high loading rates, perhaps due to reduced void growth caused by H trapped strongly at undissolved metal carbides.

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Section: The H-uptake-capacity Dependence Ofsupporting

confidence: 60%

Internal hydrogen embrittlement of ultrahigh-strength AERMET 100 steel

Thomas

Scully

Gangloff

2003

Metall Mater Trans A

139

110

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“…Hollow ones represent bubble formation, filled ones represent no evident bubble formation, half-filled ones represent that bubble formation also depends on variables other than ion energy and flux. The connection between hydrogen self-clustering and hydrogen bubble formation was also reflected by a few earlier experiments [22,63,64], where cleavage cracks in bcc iron were induced by electrochemical hydrogen charging even when no external strain was applied. The cleavage cracks were observed to initiate and propagate along {001}<110> directions, accompanied by clear dislocation emission.…”

Section: Possible Mechanism Of Hydrogen Bubble Nucleation Via Self-cl...mentioning

confidence: 64%

Hydrogen bubble nucleation by self-clustering: density functional theory and statistical model studies using tungsten as a model system

Hou¹,

Kong²,

Sun³

et al. 2018

Nucl. Fusion

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Low-energy hydrogen irradiation is known to induce bubble formation in tungsten, while its atomistic mechanisms remain little understood. Using first-principles calculations and statistical models, we studied the self-clustering behavior of hydrogen in tungsten. Unlike previous speculations that hydrogen self-clusters are energetically unstable owing to the general repulsion between two hydrogens, we demonstrated that hydrogen self-cluster becomes more favorable as the cluster size increases. We found that hydrogen atoms would form two-dimensional platelet-like structures along {100} planes. These hydrogen self-clustering behaviors can be quantitative understood by the competition between long-ranged elastic attraction and local electronic repulsion. Further statistical analysis showed that there exists a critical hydrogen concentration above which hydrogen self-clusters are thermodynamically stable and kinetically feasible. Based on this critical hydrogen concentration, the plasma loading conditions under which hydrogen self-clusters form were predicted. Our predictions showed excellent agreement with experimental results of hydrogen bubble formation in tungsten exposed to low-energy hydrogen irradiation. Finally, we proposed a possible mechanism for the hydrogen bubble nucleation via hydrogen self-clustering. This work provides mechanistic insights and quantitative models towards understanding of plasma-induced hydrogen bubble formation in plasma-facing tungsten.

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“…[59] The situation explored by Gerberich and coworkers is depicted in Figure 2, which shows dislocation emission from a crack tip with the dislocation structure being represented by a linear array of dislocations. [60] This structure yielded for the mode I threshold stress intensity, K I th :…”

Section: Proposed Mechanismsmentioning

confidence: 99%

Hydrogen Embrittlement Understood

Robertson

Sofronis

Nagao

et al. 2015

Metall Mater Trans B

441

186

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The connection between hydrogen-enhanced plasticity and the hydrogen-induced fracture mechanism and pathway is established through examination of the evolved microstructural state immediately beneath fracture surfaces including voids, ''quasi-cleavage,'' and intergranular surfaces. This leads to a new understanding of hydrogen embrittlement in which hydrogenenhanced plasticity processes accelerate the evolution of the microstructure, which establishes not only local high concentrations of hydrogen but also a local stress state. Together, these factors establish the fracture mechanism and pathway.

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The role of stress state on hydrogen cracking in Fe-Si single crystals

Cited by 49 publications

References 35 publications

Internal hydrogen embrittlement of ultrahigh-strength AERMET 100 steel

Internal hydrogen embrittlement of ultrahigh-strength AERMET 100 steel

Hydrogen bubble nucleation by self-clustering: density functional theory and statistical model studies using tungsten as a model system

Hydrogen Embrittlement Understood

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