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Effect of metallurgical factors on the pitting corrosion behavior of super austenitic stainless steel weld in an acidic chloride environment

Published online by Cambridge University Press:  27 February 2017

Sung Jin Kim*
Affiliation:
Department of Advanced Materials Engineering, Sunchon National University, Jungang-ro, Suncheon 540-742, Republic of Korea
Seung Gab Hong
Affiliation:
POSCO Steel Solution Marketing Division, Geidong-Dong, Pohang 790-704, Republic of Korea
Min-suk Oh*
Affiliation:
Automotive Components & Materials R&D Group, Korea Institute of Industrial Technology, Gwanju 500-480, Republic of Korea
*
a)Address all correspondence to these authors. e-mail: [email protected]
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Abstract

This study examined the effects of a variety of metallurgical factors on the electrochemical corrosion behavior of superaustenitic stainless steel welds. First, the effects of the sigma (σ)-phase on the corrosion behavior were studied by means of a three-dimensional-atom probe. Cr and Mo depletion areas formed around the σ-phases which are precipitated in the interdendritic area were clearly observed. Second, the effects of oxide inclusion on the pitting corrosion of the steel welds were analyzed. The utilization of high resolution transmission electron microscope clearly demonstrated that the thickness and Cr content of the passive film formed on the steel surface decreased significantly with decreasing distance to the oxide inclusion, resulting in a deterioration of the corrosion resistance. Third, the effects of alloying elements, Cu and Al, were evaluated using an electrochemical polarization technique. This confirmed that Cu has a detrimental effect on the resistance to localized corrosion of the steel. The addition of Al up to 0.25 wt% had no significant effects on corrosion resistance in a chloride environment despite the presence of an Al-based oxide layer (Al2O3) on the outermost surface.

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Articles
Copyright
Copyright © Materials Research Society 2017 

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Footnotes

Contributing Editor: Jürgen Eckert

References

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