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Stress corrosion cracking of Inconel 600 in aqueous solutions at elevated temperature Part II: Effects of chloride and sulphate ions on the electrochemical behaviour of Inconel 600
Author(s) -
Ashour E. A.,
Schneider F.,
Mummert K.
Publication year - 1997
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.19970480702
Subject(s) - chloride , corrosion , oxide , materials science , inconel , aqueous solution , chromate conversion coating , stress corrosion cracking , electrolyte , dissolution , electrochemistry , inorganic chemistry , metallurgy , crevice corrosion , metal , pitting corrosion , chromium , chemistry , electrode , alloy
The influencing effects of temperature, potential and electrolyte composition on the electrochemical behaviour of Inconel 600 in aqueous solutions are presented. Considering these effects the connection between the data have been obtained from chemo‐mechanical fracture investigation on CT‐samples in Part I of this paper and pitting corrosion are discussed. The results have shown that chloride ions depassivate the surfaces of cracks locally and hinder the formation of a new protective oxide layer on the fracture surfaces. Furthermore, chloride promotes the dissolution of metal and initiates the cracking, respectively. The resulting crevice corrosion promotes an increase of hydrogen absorption by the metal. The increase of the hydrogen content of the metal influences the mechanical fracture behaviour. Contrary, sulphateions inhibit the initiation of corrosion mainly due to a hinderance of chloride ions adsorption on active sites of the fracture surfaces. The initiation of localized corrosion in the crevice region may be stimulated by chromate ions formed by oxidation of chromium from the oxide layer or the base metal in oxygen containing solutions.