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Studies on the Pitting Corrosion of the Delta‐52 Steel in aqueous solutions. 2. Variation of the pitting potential in relation to the concentration of the aggressive anion
Author(s) -
El Haleem S. M. Abd,
El Reheem S. S. Abd,
Sh. Shalaby M.,
Azzam A. M.
Publication year - 1976
Publication title -
materials and corrosion
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.487
H-Index - 55
eISSN - 1521-4176
pISSN - 0947-5117
DOI - 10.1002/maco.19760270905
Subject(s) - pitting corrosion , halide , dissolution , chloride , iodide , polarization (electrochemistry) , chemistry , inorganic chemistry , aqueous solution , ion , oxide , corrosion , hydroxide , bromide , materials science , metallurgy , organic chemistry
Potentiodynamic anodic polarization curves have been traced for an electrode of the steel Delta‐52 (0.40, 0.78Mn, 0.045 S, 0.06P, 0.23 Si): the aggresive media used were potassium hydroxide without and with additions of potassium chloride, bromide and iodide. The oxide film present on the steel surface does not inhibit active dissolution; only at potentials exceeding+2 (S. C. E.) passivity sets in. The polarization behaviour of the steel is not influenced by the addition of the halide salts; above a certain salt concentration, however, there is a sharp increase in dissolution current. This phenomenon is an indication of the start of pitting. Between the pitting potential and the anion concentration there exists a well defined relation.