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A study on pitting initiation mechanism of super-austenitic stainless steel weld in chloride environment

Published online by Cambridge University Press:  27 September 2016

Sung Jin Kim  and
Seung Gab Hong
Sung Jin Kim*
Affiliation:
Department of Advanced Materials Engineering, Sunchon National University, Suncheon 540-742, Republic of Korea
Seung Gab Hong
Affiliation:
POSCO Steel Solution Marketing Division, Pohang 790-704, Korea
*
a)Address all correspondence to this author. e-mail: [email protected]
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Abstract

There has been controversy over the localized corrosion mechanism of super-austenitic stainless steel weld due mainly to the lack of effective evaluation technique for identification of corrosion nucleation site in weld. For this reason, an electrochemical polarization method followed by an observation of microstructure using the back-scattered electron mode in field emission-scanning electron microscopy is used. To clarify the localized corrosion mechanism, energy dispersive spectroscopy line profile analyzed by transmission electron microscopy is additionally utilized. It clearly reveals that the selective corrosion is preferentially initiated around the σ-phase precipitated in the interdendritic region in weld. The local depletion of Cr and Mo around the σ-phase can be partly replenished by the diffusion of the elements into the depleted area during the subsequent heat treatment at 1180 °C.

Keywords

steelcorrosionwelding
Type
Articles
Information
Journal of Materials Research , Volume 31 , Issue 21 , 14 November 2016 , pp. 3345 - 3351
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Copyright
Copyright © Materials Research Society 2016 

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Footnotes

Contributing Editor: Jürgen Eckert

References

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