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

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 fra...

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Main Authors: Birenis Domas, Ogawa Yuhei, Matsunaga Hisao, Takakuwa Osamu, Yamabe Junichiro, Prytz Øystein, Thøgersen Annett
Format: Article
Language:English
Published: EDP Sciences 2018-01-01
Series:MATEC Web of Conferences
Online Access:https://doi.org/10.1051/matecconf/201816503010
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spelling doaj-fafe3daa5a5f4780a9ff76e4619111412021-02-02T07:48:53ZengEDP SciencesMATEC Web of Conferences2261-236X2018-01-011650301010.1051/matecconf/201816503010matecconf_fatigue2018_03010Hydrogen-assisted fatigue crack propagation in a pure BCC iron. Part II: Accelerated regime manifested by quasi-cleavage fracture at relatively high stress intensity range valuesBirenis DomasOgawa YuheiMatsunaga HisaoTakakuwa OsamuYamabe JunichiroPrytz ØysteinThøgersen AnnettHydrogen 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.https://doi.org/10.1051/matecconf/201816503010
collection DOAJ
language English
format Article
sources DOAJ
author Birenis Domas
Ogawa Yuhei
Matsunaga Hisao
Takakuwa Osamu
Yamabe Junichiro
Prytz Øystein
Thøgersen Annett
spellingShingle Birenis Domas
Ogawa Yuhei
Matsunaga Hisao
Takakuwa Osamu
Yamabe Junichiro
Prytz Øystein
Thøgersen Annett
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
MATEC Web of Conferences
author_facet Birenis Domas
Ogawa Yuhei
Matsunaga Hisao
Takakuwa Osamu
Yamabe Junichiro
Prytz Øystein
Thøgersen Annett
author_sort Birenis Domas
title 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
title_short 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
title_full 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
title_fullStr 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
title_full_unstemmed 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
title_sort 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
publisher EDP Sciences
series MATEC Web of Conferences
issn 2261-236X
publishDate 2018-01-01
description 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.
url https://doi.org/10.1051/matecconf/201816503010
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AT prytzøystein hydrogenassistedfatiguecrackpropagationinapurebccironpartiiacceleratedregimemanifestedbyquasicleavagefractureatrelativelyhighstressintensityrangevalues
AT thøgersenannett hydrogenassistedfatiguecrackpropagationinapurebccironpartiiacceleratedregimemanifestedbyquasicleavagefractureatrelativelyhighstressintensityrangevalues
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