Corrosion Science and Technology

The Corrosion Science Society of Korea (한국부식방식학회)
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Hydrogen Diffusion in APX X65 Grade Linepipe Steels

  • Park, Gyu Tae (Department of Materials Science and Engineering, Pohang University of Science and Technology) ;
  • Koh, Seong Ung (Department of Materials Science and Engineering, Pohang University of Science and Technology) ;
  • Kim, Kyoo Young (Department of Materials Science and Engineering, Pohang University of Science and Technology) ;
  • Jung, Hwan Gyo (Technical Research Center, POSCO)
  • Published : 2006.08.01
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Abstract

Hydrogen permeation measurements have been carried out on API X65 grade linepipe steel. In order to study the effect of steel microstructure on hydrogen diffusion behavior in linepipe steel, the accelerated cooling condition was applied and then three different kinds of microstructures were obtained. Hydrogen permeation measurement has been performed in reference to modified ISO17081 (2004) and ZIS Z3113 method. Hydrogen trapping parameters in these steels were evaluated in terms of the effective diffusivity ($D_{eff}$), permeability ($J_{ss}L$) and the amount of diffusible hydrogen. In this study, microstructures which affect both hydrogen trapping and diffusion were degenerated pearlite (DP), acicular ferrite (AF), bainite and martensite/austenite constituents (MA). The low $D_{eff}$ and $J_{ss}L$ mean that more hydrogen can be trapped reversibly or irreversibly and the corresponding steel microstructure is dominant hydrogen trapping site. The large amount of diffusible hydrogen means that corresponding steel microstructure is predominantly reversible. The results of this study suggest that the hydrogen trapping efficiency increases in the order of DP, bainite and AF, while AF is the most efficient reversible trap.

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References

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