Effect of Delta Ferrite on Corrosion Resistance of Type 316L Stainless Steel in Acidic Chloride Solution by Micro-Droplet Cell

Abstract:

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More than 2% δ-ferrite phase is presented in type 316L stainless steels due to improvement of hot workability or welding process. In order to clarify the mechanism on how the δ-ferrite affects the corrosion resistance, electrochemical tests in a micro-droplet cell were conducted and microstructures were analyzed by TEM-EDS and SEM-EDS. Especially, the micro-droplet cell was modified at our laboratory to observe the polarization behavior of δ-ferrite phase in an acidic chloride solution. The anodic polarization behavior in both active zone and passive zone was affected by δ-ferrite. The degradation of corrosion resistance in the low potential zone with δ-ferrite phase is due to the preferential dissolution of a matrix, γ phase. It is explained with the fact that the formation of δ-ferrite lowers the concentrations of chromium and molybdenum in γ phase. It is also confirmed by potentiostatic test, EDS analyses and phase-equilibrium prediction. In addition, the micro-droplet cell and EDS analysis reveled that the pitting potential in the neutral pH solution was affected by Ca containing inclusion rather than δ-ferrite phase.

Info:

Periodical:

Solid State Phenomena (Volumes 124-126)

Edited by:

Byung Tae Ahn, Hyeongtag Jeon, Bo Young Hur, Kibae Kim and Jong Wan Park

Pages:

1533-1536

DOI:

10.4028/www.scientific.net/SSP.124-126.1533

Citation:

S. Y. Kim et al., "Effect of Delta Ferrite on Corrosion Resistance of Type 316L Stainless Steel in Acidic Chloride Solution by Micro-Droplet Cell", Solid State Phenomena, Vols. 124-126, pp. 1533-1536, 2007

Online since:

June 2007

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$35.00

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