Physical Chemistry of Electrochemical Processes at the Tip of a Corrosion-Mechanical Crack

Classical corrosion electrochemistry considers processes on a nonstressed surface of a metal. In applying mechanical stresses, the surface becomes chemically active, which leads to a considerable change in the conditions of cathodic and anodic conjugate processes, violation of the integrity of surfa...

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Bibliographic Details
Published in:Materials science (New York, N.Y.) N.Y.), 2003-09, Vol.39 (5), p.750-753
Main Author: Petrov, L N
Format: Article
Language:English
Subjects:
Physical chemistry
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Summary:Classical corrosion electrochemistry considers processes on a nonstressed surface of a metal. In applying mechanical stresses, the surface becomes chemically active, which leads to a considerable change in the conditions of cathodic and anodic conjugate processes, violation of the integrity of surface films, and diffusion of hydrogen into a zone of maximum three-axial tensile stresses that can result in structural changes in the metal. In the present work, within the framework of electrochemistry of a stress-strain metal, we consider several electrochemical processes in cracks. A corrosive medium essentially accelerates propagation of stress cracks, changing the mechanism itself of their propagation because a part of the mechanical energy under loading is transformed into chemical energy, which leads to the appearance of several corrosion galvanic elements in the vicinity of the crack. The main of these elements are the following: the stress-nonstressed metal, freshly formed surface-old surface of the metal, and a "hydrogen" galvanic element or the hydrogenated tip of the crack-nonhydrogenated (less hydrogenated) walls of the crack. The mentioned galvanic elements are united in one general element that causes corrosion of the tip of a crack and hydrogenation of its cathodic walls.
ISSN:1068-820X
1573-885X
DOI:10.1023/B:MASC.0000023517.08761.ba