Zairyo-to-Kankyo
Online ISSN : 1881-9664
Print ISSN : 0917-0480
ISSN-L : 0917-0480
Research Paper
Effects of Metal Ions on Pitting Potential and Pit Growth Behavior for 316L Stainless Steel
Yoshinori IsomotoShinya Matsuo
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2012 Volume 61 Issue 5 Pages 213-218

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Abstract

A potentiostatic method was used to measure pitting potential for SUS316L stainless steel and compared with a potentiodynamic polarization method standardized by JIS G 0577. Test conditions were sodium chloride solutions from 0.008 to 1 M containing metal ions less than 110 ppm at temperatures of 300 and 323 K. The pitting potentials of SUS316L steel decreased with the increases in concentration of chloride ions and in temperature. The test results of pitting potential were consistent between the potentiostatic and potentiodynamic polarization methods. The presence of metal ions in a 0.08 M sodium chloride solution greatly decreased the pitting potential of SUS316L steel. Pits were grown from a steel surface by using a galvanostatic method proposed in this study, and observed in a cross-sectional surface after the growth tests. As a results, it is found that the low current density or metal irons of Mn2+ and Cr3+ added in the sodium chloride solution changed the aspect ratio of cross-sectional pit morphology and promoted deeper pit growth. Mechanisms of pit initiation and growth were discussed in this study.

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© 2012 Japan Society of Corrosion Engineering
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