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International Journal of Fracture

, Volume 209, Issue 1–2, pp 223–229 | Cite as

Forming mechanism of delamination cracks observed during tensile and fracture toughness testing of X70 pipeline steel

  • Dong-Yeob Park
  • Babak Shalchi Amirkhiz
  • Jean-Philippe Gravel
  • Jie Liang
  • Renata Zavadil
  • Pei Liu
  • Da-Ming Duan
Brief Note
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Abstract

In this study, we have investigated microstructures of the delamination cracks observed from tensile and fracture toughness test specimens using an API X70 pipeline steel. It is found that the delaminations observed from both tensile and toughness specimens are intergranular fractures. At the occurrence, characteristics of brittle fracture were observed, but it was found not to be a brittle fracture as the delaminations were induced by plastic deformation. It is shown that severe plastic deformation produced strain concentration around particles located along grain boundaries and caused decohesion between adjacent grains, resulting in intergranular fracture.

Keywords

Split Delamination Brittle fracture Tensile test Toughness test Intergranular fracture 

Notes

Acknowledgements

This research work was funded by TransCanada Pipelines Limited and the Canadian federal government Program of Energy Research and Development (PERD). We thank Dr. Chris DeBuhr at the Instrumentation Facility for Analytical Electron Microscopy (IFFAEM), University of Calgary, for taking SEM-based fractographs, and Muhammad Arafin at CanmetMATERIALS for technical advice.

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Copyright information

© Her Majesty the Queen in Right of Canada 2017

Authors and Affiliations

  • Dong-Yeob Park
    • 1
  • Babak Shalchi Amirkhiz
    • 2
  • Jean-Philippe Gravel
    • 1
  • Jie Liang
    • 2
  • Renata Zavadil
    • 2
  • Pei Liu
    • 2
  • Da-Ming Duan
    • 3
  1. 1.CanmetMATERIALSNatural Resources CanadaCalgaryCanada
  2. 2.CanmetMATERIALSNatural Resources CanadaHamiltonCanada
  3. 3.TransCanadaCalgaryCanada

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