This paper is concerned with developing an understanding of the transition between modes 1 and 2 of the bi-modal characteristic often observed for corrosion (mass) loss of many different alloys and in a variety of longer-term (years) exposure conditions. Corrosion losses and pit depth and size for carbon steels (0.01 wt%, 0.04 wt%, and 0.06 wt% C) immersed continuously in sheltered 20°C (av.) seawater, 30°C (constant) seawater, and 70°C (constant) distilled water environments are reported with observations at 14 d and 28 d intervals over 1.4 y. The data allow clear demonstration of bi-modal behavior and variability in mass loss much less than typical for unprotected environments. All cases showed significant development of pit depths and pit areas particularly later in mode 1, through the transition phase and into mode 2. Using established observations of pitting mechanisms, the development of pitting is interpreted as facilitating the reduction in pH at the corrosion interface that permits the cathodic reaction to change from oxygen reduction in mode 1 to hydrogen evolution in mode 2, consistent with longer-term predominantly anaerobic corrosion in the later part of the bi-modal model. The observations also shed some light on the relationship between pitting corrosion and what is conventionally referred to as uniform corrosion.
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1 May 2022
Research Article|
March 16 2022
The Transition from Short- to Long-Term Marine Corrosion of Carbon Steels: 1. Experimental Observations Available to Purchase
Robert E. Melchers;
Robert E. Melchers
‡
*Centre for Infrastructure Performance and Reliability, The University of Newcastle, Callaghan 2308, New South Wales, Australia.
‡Corresponding author. E-mail: [email protected].
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Robert Jeffrey
Robert Jeffrey
*Centre for Infrastructure Performance and Reliability, The University of Newcastle, Callaghan 2308, New South Wales, Australia.
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‡Corresponding author. E-mail: [email protected].
Online ISSN: 1938-159X
Print ISSN: 0010-9312
© 2022, AMPP
2022
CORROSION (2022) 78 (5): 415–426.
Citation
Robert E. Melchers, Robert Jeffrey; The Transition from Short- to Long-Term Marine Corrosion of Carbon Steels: 1. Experimental Observations. CORROSION 1 May 2022; 78 (5): 415–426. https://doi.org/10.5006/4061
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