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Susceptibility of acicular ferrite and upper bainite microstructures to hydrogen assisted cold cracking propagation

Journal Article


Abstract


  • Acicular ferrite (AF) and upper bainite (UB) are microstructural constituents commonly found in ferritic weld metals. Both microstructures are formed within a similar temperature range and by the same type of transformation mechanisms. They have however, substantially different morphologies and microstructural features that govern both their mechanical properties and hydrogen embrittlement susceptibility. This work shows that despite substantial microstructural differences, the mechanical properties of both microstructural constituents were quite similar. However, the microstructural differences were found to significantly affect the hydrogen crack propagation resistance. Hydrogen assisted cold cracking (HACC) propagates along a path of least resistance through the surrounding microstructure. The unit crack path was significantly shorter for AF than for UB, which implied more frequent changes in direction and thus increased dissipation of energy from the crack driving force. These results suggest that AF, possessing fine interlocking grains and high angle grain boundaries (HAGB), increases the localised resistance to HACC propagation more than UB due to the impediment of brittle, cleavage-like crack propagation at HAGB���s.

UOW Authors


  •   Barbaro, Frank (external author)
  •   Linton, Valerie (external author)

Publication Date


  • 2017

Citation


  • Costin, W., Lavigne, O., Kotousov, A. G., Ghomashchi, R., Brown, I. H., Linton, V., & Barbaro, F. J. (2017). Susceptibility of acicular ferrite and upper bainite microstructures to hydrogen assisted cold cracking propagation. Materials Science Forum, 909 MSF, 44-49. doi:10.4028/www.scientific.net/MSF.909.44

Scopus Eid


  • 2-s2.0-85036474594

Web Of Science Accession Number


Start Page


  • 44

End Page


  • 49

Volume


  • 909 MSF

Issue


Place Of Publication


Abstract


  • Acicular ferrite (AF) and upper bainite (UB) are microstructural constituents commonly found in ferritic weld metals. Both microstructures are formed within a similar temperature range and by the same type of transformation mechanisms. They have however, substantially different morphologies and microstructural features that govern both their mechanical properties and hydrogen embrittlement susceptibility. This work shows that despite substantial microstructural differences, the mechanical properties of both microstructural constituents were quite similar. However, the microstructural differences were found to significantly affect the hydrogen crack propagation resistance. Hydrogen assisted cold cracking (HACC) propagates along a path of least resistance through the surrounding microstructure. The unit crack path was significantly shorter for AF than for UB, which implied more frequent changes in direction and thus increased dissipation of energy from the crack driving force. These results suggest that AF, possessing fine interlocking grains and high angle grain boundaries (HAGB), increases the localised resistance to HACC propagation more than UB due to the impediment of brittle, cleavage-like crack propagation at HAGB���s.

UOW Authors


  •   Barbaro, Frank (external author)
  •   Linton, Valerie (external author)

Publication Date


  • 2017

Citation


  • Costin, W., Lavigne, O., Kotousov, A. G., Ghomashchi, R., Brown, I. H., Linton, V., & Barbaro, F. J. (2017). Susceptibility of acicular ferrite and upper bainite microstructures to hydrogen assisted cold cracking propagation. Materials Science Forum, 909 MSF, 44-49. doi:10.4028/www.scientific.net/MSF.909.44

Scopus Eid


  • 2-s2.0-85036474594

Web Of Science Accession Number


Start Page


  • 44

End Page


  • 49

Volume


  • 909 MSF

Issue


Place Of Publication