The necessity of both plasticity and brittleness in the fracture thresholds of iron

Gerberich, William W; Oriani, R. A.; Lji, M.-J.; Chen, X.; Foecke, Timothy J.

doi:10.1080/01418619108204854

Cited by 191 publications

(94 citation statements)

References 32 publications

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“…Surrounding-tip plasticity is represented by a superdislocation located at the centroid of the highly strained continuum plastic zone, and related to stress intensity. [44,81,82] Crack tip stress of order 16 to 25 GPa is predicted for Fe-Si and Mo, [44] and is maximum at 20 to 100 nm ahead of the crack tip surface. This estimate is consistent with Oriani's original decohesion model.…”

Section: E Threshold For Heacmentioning

confidence: 99%

“…[22,46] x crit reflects the interaction of crack tip tensile stress and H concentration gradient, and is of order 1 lm for high strength Ti, Fe, Al, and Ni-based alloys, [45] suggesting damage localization at the maximum in the crack tip r H distribution [47] or H-sensitive dislocation structure. [38,44] D H for H in aged Monel K-500 at 298 K (25°C) was reported to be 5 to 6 9 10 À11 cm 2 /s, [48] 1.5 to 1.9 9 10 À10 cm 2 /s, [24] and 9 9 10 À11 to 4 9 10 À10 cm 2 /s, [29] suggesting an upperbound da/dt II from Eq.…”

Section: Introductionmentioning

confidence: 99%

“…This model captures the interplay between crack tip plasticity and stress-based decohesion. [44] For a wide range of high strength alloy-environment combinations that crack by HEAC, H diffusion in the crack tip FPZ limits da/dt II , [45] provided that surface reaction rate is rapid. Modeling of H diffusion ahead of a discontinuously propagating crack yielded [42,46] :…”

Section: Introductionmentioning

confidence: 99%

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Measurement and Modeling of Hydrogen Environment-Assisted Cracking in Monel K-500

Gangloff

Burns

et al. 2014

Metall Mater Trans A

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Hydrogen environment-assisted cracking (HEAC) of Monel K-500 is quantified using slow-rising stress intensity loading with electrical potential monitoring of small crack propagation and elastoplastic J-integral analysis. For this loading, with concurrent crack tip plastic strain and H accumulation, aged Monel K-500 is susceptible to intergranular HEAC in NaCl solution when cathodically polarized at À800 mV SCE (E A , vs saturated calomel) and lower. Intergranular cracking is eliminated by reduced cathodic polarization more positive than À750 mV SCE . Crack tip diffusible H concentration rises, from near 0 wppm at E A of À765 mV SCE , with increasing cathodic polarization. This behavior is quantified by thermal desorption spectroscopy and barnacle cell measurements of hydrogen solubility vs overpotential for planar electrodes, plus measured-local crevice potential, and pH scaled to the crack tip. Using crack tip H concentration, excellent agreement is demonstrated between measurements and decohesion-based model predictions of the E A dependencies of threshold stress intensity and Stage II growth rate. A critical level of cathodic polarization must be exceeded for HEAC to occur in aged Monel K-500. The damaging-cathodic potential regime likely shifts more negative for quasi-static loading or increasing metallurgical resistance to HEAC.

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Section: E Threshold For Heacmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Measurement and Modeling of Hydrogen Environment-Assisted Cracking in Monel K-500

Gangloff

Burns

et al. 2014

Metall Mater Trans A

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“…Accordingly, the following is summarized. On top of intensive activities in deformation/hydrogen embrittlement in austenitic stainless steels, including fracture mechanics methodology [13][14][15][16][17][18][19], nano tests have been supplemented. The extension has involved nano-indentation and micro scratch tests and other small volume effects at surfaces.…”

Section: Discussionmentioning

confidence: 99%

External surfaces affected by free hydrogen in metastable austenitic stainless steels

Katz

2009

WIT Transactions on Engineering Sciences

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Malfunction in service of contact components due to fretting fatigue enhanced mainly by the environmental interaction provided incentives to broaden and deepen the understanding of this complex time-dependent process. Metastable austenitic stainless steels affected by solid solution free hydrogen interaction, deserves further elaboration and input. In fact, the aforementioned systems combine both materials and aggressive environment that suppose to be candidates for important applications in future energy technology. As such, the whole issue of tribology turns out to be a major design topic in terms of structural integrity and service life considerations. Fretting fatigue driving force includes in addition to the remote load also the environmental interaction effects. By considering the deformation/environment interaction in metastable austenitic stainless steels at least two origins of damage are recognized, namely, sequential events connected to phase stability and hydrogen embrittlement aspects. Materials were selected from the AISI 300 group of austenitic stainless steels in general, with special attention to the relatively stable AISI 316L steel. Hydrogen was provided either by electrolytic cathodic charging or by high temperature/pressure gaseous charging. Following the current information, regarding fretting fatigue, life degradation due to internal/external hydrogen has been established. Thus, the present study is centered on tracking surface modification activated by environmental interaction confined to the near surface hydrogen affected layer. For this purpose, global and local findings were gathered in a bottom-top methodology. Standard and novel techniques were utilized including nano indentation, scratch tests and acoustic emission tracking that enabled visualization and measurements. Experimentally based, the study emphasized the local approach in contrast to the macroscopic contact mechanics approach. On a local resolution a dislocation model has been attempted, which facilitated advanced analysis as related to wear, damage evolution and near surface behavior assessment.

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“…For an atomistically sharp IG crack tip, Thompson and then Kameda [40] invoked a dislocation-free zone between the crack tip and dislocation pile-up; o-rr in this zone equaled ( 4 -7 )cys at applied K typical of hydrogen cracking thresholds and joined the HRR field at the outer edge. Gerberich and coworkers modeled interaction of a distribution of dislocations that dominate very-near tip stresses and a superdislocation (removed from the tip) that defines global crack tip plasticity with work hardening [34,41].…”

Section: 11mentioning

confidence: 99%

Critical issues in hydrogen assisted cracking of structural alloys

Gangloff

2008

Environment-Induced Cracking of Materials

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The necessity of both plasticity and brittleness in the fracture thresholds of iron

Cited by 191 publications

References 32 publications

Measurement and Modeling of Hydrogen Environment-Assisted Cracking in Monel K-500

Measurement and Modeling of Hydrogen Environment-Assisted Cracking in Monel K-500

External surfaces affected by free hydrogen in metastable austenitic stainless steels

Critical issues in hydrogen assisted cracking of structural alloys

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