https://doi.org/10.15255/KUI.2002.024
Published: Kem. Ind. 53 (1) (2004) 1–5
Paper reference number: KUI-24/2002
Paper type: Original scientific paper
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Pitting Corrosion of Stainless Steel 304L in Chloride Solutions and Natural Salt Waters

B. Kulušić, L. Krstulović and J. Ivić

Abstract

The investigations of the influence of the chloride concentration and experimental conditions on pit formation and pit growth during the metastable and stable period on type 304L stainless steel, were the subject of the present work. Measurements were made in pure chloride containing solutions in concentrations from 0,02 to 0,6 mol dm–3 as well as in natural salt waters (natural seawater and brackish water) at stagnant and flowing laboratory conditions. Anodic potentiodynamic polarization started from open-circuit potential and was continued until the pitting potential was obtained. Scan rate of 30 mV min–1 was employed in all measurements at the ambient temperature. The experiments by flow conditions have been carried out in the volume of 30 dm3 test solution using a flow rate of 1 dm3 min–1. The transition from metastable growing pit to an oxide film breakdown were followed by current fluctuations. As the chloride ione concentration increases, the open circuit potentials and the oxide film breakdown potentials undergo an increased shift in a less noble direction by stagnant and flowing experimental conditions. However, the mentioned potentials for natural salt waters (natural seawater and brackish water) are shifted to the noble direction compared to the pure chloride containing solutions.

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Keywords

stainless steel, pitting corrosion, chloride ione, natural seawater