STP1277

    Effect of Metallurgical Factors on the Electrochemical Noise Measured on AISI Type 430 Stainless Steels in Chloride-Containing Media

    Published: Jan 1996


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    Abstract

    Potentiostatic noise measurements are performed on a series of AISI 430 type ferritic stainless steels containing controlled amounts of sulfur (from 8 up to 47 ppm) and titanium (up to 0.37 wt%), in 0.02M sodium chloride (NaCl) aqueous solution (pH 6.6), in a range of potentials below the pitting potential. We focus on the evolution of the shape of the current transients, going from a titanium (Ti) free and 41-ppm sulfur-containing alloy to different Ti-bearing alloys with comparable amount of sulfur (∼40 ppm). The results are compared to the case of a Ti-free and low sulfur (8-ppm) containing alloy. The shape of the anodic current transients obeys a power law, tn. We distinguish two different situations, with n either less or larger than 1, which can be associated with the Ti and sulfur content in the steel. The influence of the exposure time under polarization is also discussed. It appears that for the manganese sulfide (MnS)-containing alloys, after prolonged polarization, the shape of the metastable pitting events evolves toward that found for MnS-free alloys (Ti-bearing), or low-sulfur-containing alloys. Attention is drawn to the possible relationship between the shape of the current transients and the metallurgical defects acting as pitting initiation sites.

    Keywords:

    potentiostatic electrochemical noise measurements, stainless steels, inclusions, titanium, manganese sulfide, pitting


    Author Information:

    Gorse, D
    Research scientist and graduate student, CECM-CNRS, Vitry sur Seine Cedex,

    Boulleret, C
    Research scientist and graduate student, CECM-CNRS, Vitry sur Seine Cedex,

    Baroux, B
    Professor, Institut National Polytechnique de Grenoble, LTPCM, URA CNRS 29, ENSEEG, Saint Martin d'Hères,


    Paper ID: STP37968S

    Committee/Subcommittee: G01.11

    DOI: 10.1520/STP37968S


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