Strain gradient plasticity-based modeling of hydrogen environment assisted cracking
Finite element analysis of stress about a blunt crack tip, emphasizing finite strain and phenomenological and mechanism-based strain gradient plasticity (SGP) formulations, is integrated with electrochemical assessment of occluded-crack tip hydrogen (H) solubility and two H-decohesion models to pred...
| Main Authors: | , , |
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| Format: | Journal article |
| Language: | English |
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Elsevier
2016
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| _version_ | 1826312385369997312 |
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| author | Martinez-Paneda, E Niordson, CF Gangloff, RP |
| author_facet | Martinez-Paneda, E Niordson, CF Gangloff, RP |
| author_sort | Martinez-Paneda, E |
| collection | OXFORD |
| description | Finite element analysis of stress about a blunt crack tip, emphasizing finite strain and phenomenological and mechanism-based strain gradient plasticity (SGP) formulations, is integrated with electrochemical assessment of occluded-crack tip hydrogen (H) solubility and two H-decohesion models to predict hydrogen environment assisted crack growth properties. SGP elevates crack tip geometrically necessary dislocation density and flow stress, with enhancement declining with increasing alloy strength. Elevated hydrostatic stress promotes high-trapped H concentration for crack tip damage; it is imperative to account for SGP in H cracking models. Predictions of the threshold stress intensity factor and H-diffusion limited Stage II crack growth rate agree with experimental data for a high strength austenitic Ni-Cu superalloy (Monel®K-500) and two modern ultra-high strength martensitic steels (AerMet™100 and Ferrium™M54) stressed in 0.6 M NaCl solution over a range of applied potential. For Monel®K-500, KTH is accurately predicted versus cathodic potential using either classical or gradient-modified formulations; however, Stage II growth rate is best predicted by a SGP description of crack tip stress that justifies a critical distance of 1 μm. For steel, threshold and growth rate are best predicted using high-hydrostatic stress that exceeds 6 to 8 times alloy yield strength and extends 1 μm ahead of the crack tip. This stress is nearly achieved with a three-length phenomenological SGP formulation, but additional stress enhancement is needed, perhaps due to tip geometry or slip-microstructure. |
| first_indexed | 2024-03-07T08:29:41Z |
| format | Journal article |
| id | oxford-uuid:c1bbf655-30b5-47cc-b246-d0a48431b85d |
| institution | University of Oxford |
| language | English |
| last_indexed | 2024-03-07T08:29:41Z |
| publishDate | 2016 |
| publisher | Elsevier |
| record_format | dspace |
| spelling | oxford-uuid:c1bbf655-30b5-47cc-b246-d0a48431b85d2024-02-28T16:17:47ZStrain gradient plasticity-based modeling of hydrogen environment assisted crackingJournal articlehttp://purl.org/coar/resource_type/c_dcae04bcuuid:c1bbf655-30b5-47cc-b246-d0a48431b85dEnglishSymplectic ElementsElsevier2016Martinez-Paneda, ENiordson, CFGangloff, RPFinite element analysis of stress about a blunt crack tip, emphasizing finite strain and phenomenological and mechanism-based strain gradient plasticity (SGP) formulations, is integrated with electrochemical assessment of occluded-crack tip hydrogen (H) solubility and two H-decohesion models to predict hydrogen environment assisted crack growth properties. SGP elevates crack tip geometrically necessary dislocation density and flow stress, with enhancement declining with increasing alloy strength. Elevated hydrostatic stress promotes high-trapped H concentration for crack tip damage; it is imperative to account for SGP in H cracking models. Predictions of the threshold stress intensity factor and H-diffusion limited Stage II crack growth rate agree with experimental data for a high strength austenitic Ni-Cu superalloy (Monel®K-500) and two modern ultra-high strength martensitic steels (AerMet™100 and Ferrium™M54) stressed in 0.6 M NaCl solution over a range of applied potential. For Monel®K-500, KTH is accurately predicted versus cathodic potential using either classical or gradient-modified formulations; however, Stage II growth rate is best predicted by a SGP description of crack tip stress that justifies a critical distance of 1 μm. For steel, threshold and growth rate are best predicted using high-hydrostatic stress that exceeds 6 to 8 times alloy yield strength and extends 1 μm ahead of the crack tip. This stress is nearly achieved with a three-length phenomenological SGP formulation, but additional stress enhancement is needed, perhaps due to tip geometry or slip-microstructure. |
| spellingShingle | Martinez-Paneda, E Niordson, CF Gangloff, RP Strain gradient plasticity-based modeling of hydrogen environment assisted cracking |
| title | Strain gradient plasticity-based modeling of hydrogen environment assisted cracking |
| title_full | Strain gradient plasticity-based modeling of hydrogen environment assisted cracking |
| title_fullStr | Strain gradient plasticity-based modeling of hydrogen environment assisted cracking |
| title_full_unstemmed | Strain gradient plasticity-based modeling of hydrogen environment assisted cracking |
| title_short | Strain gradient plasticity-based modeling of hydrogen environment assisted cracking |
| title_sort | strain gradient plasticity based modeling of hydrogen environment assisted cracking |
| work_keys_str_mv | AT martinezpanedae straingradientplasticitybasedmodelingofhydrogenenvironmentassistedcracking AT niordsoncf straingradientplasticitybasedmodelingofhydrogenenvironmentassistedcracking AT gangloffrp straingradientplasticitybasedmodelingofhydrogenenvironmentassistedcracking |