The effects of stress on the internal structure and energy characteristics of metals are discussed with relationship to their influence on corrosion reactions. The nature and importance of residual stresses and the non-homogeneity of worked metals are emphasized. Recent concepts of the nature of grain boundaries are reviewed and their importance in reactions where stress and corrosion act in a conjoint manner is described. A review of the literature reveals that stresses (either by applied loads or of a residual nature) may influence the nature, rate and distribution of corrosion reactions in several ways: a) by increasing the internal energy level of the metal system and causing a possible shift of electrochemical potential in a more active direction, b) by causing an intrinsic increase in the rate of corrosion, c) by damaging protective surface films, d) by influencing polarization reactions, e) by changing the metallurgical characteristics of the metal system in promoting phase transformations, precipitation, etc., f) by accelerating the rate of corrosion by purely mechanical effects. The exact influence of stress on rates of general corrosion is still questionable, but does not appear to be of major consequence. The most serious effects of stress are in localized corrosion phenomena such as stress-corrosion and corrosion fatigue. Stress-corrosion of alloys is particularly discussed and the influence of metal composition and structure, environment, state and degree of stress is presented. Practically all known alloy systems can be made to crack from stress-corrosion in appropriate environments. The oxide film, mechanical and electrochemical theories of stress-corrosion cracking are reviewed and it is shown that the experimental evidence favors an electrochemical mechanism. However, the exact mechanism of cracking may vary from one metal system to another and no theory presented thus far is adequate to account for all observed phenomena. Stress-corrosion cracking of alpha brass, stainless steels and magnesium alloys is still not understood clearly. Methods of protection against stress-corrosion cracking are reviewed briefly.
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August 1950
Research Article|
August 01 1950
The Influence of Stress on Corrosion⋆ (Part I of Two Parts)
Julius J. Harwood
Julius J. Harwood
Acting Head of the Metallurgy Section, Office of Naval Research, Navy Department, Washington, D. C., Mr. Harwood has been with the navy since 1941 and with the Office of Naval Research since 1946. He was secretary of the Panel on Corrosion and Surface Protection of the Research and Development Board, Department of Defense and chairman of the former corrosion sub-committee of the joint military Deterioriation Prevention Committee. He is a member of the Inter-Society Corrosion Committee.
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CORROSION (1950) 6 (8): 249–259.
