Assessment of the impact of hydrogen on the stress developed ahead of a fatigue crack

Shuai Wang, Akihide Nagao, Petros Sofronis, Ian M. Robertson

Research output: Contribution to journalArticle

Abstract

The microstructure generated in a low carbon steel under cyclic loading in air and a 40 MPa gaseous hydrogen environment has been compared as a function of distance from the crack tip. The presence of hydrogen resulted in the formation of a smaller and more equiaxed dislocation cell structure that extended further from the crack tip than the one generated in air. This enhancement and extension of the dislocation structure by hydrogen is consistent with it modifying the generation rate and mobility of dislocations as well as dislocation interactions. Qualitative assessment of the dislocation structure ahead of the crack tip found the stress ahead of the crack tip to vary linearly as ln(1/x), where x is the distance from the crack tip irrespective of the test environment. Hydrogen caused a shift to higher stresses, implying the critical damage level for crack propagation will be achieved more rapidly with a concomitant increase in the crack propagation rate.

Original languageEnglish (US)
Pages (from-to)181-188
Number of pages8
JournalActa Materialia
Volume174
DOIs
StatePublished - Aug 1 2019

Keywords

  • Electron microscopy
  • Fatigue-crack growth
  • Hydrogen embrittlement
  • Low-carbon steel
  • Plastic zone
  • Stress magnitude

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Ceramics and Composites
  • Polymers and Plastics
  • Metals and Alloys

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