Stress Corrosion Spectrum

Despite many attempts over the years to rationalise stress corrosion cracking in terms of a single mechanism, it is proposed that the growing body of evidence more readily supports a continuous spectrum of mechanisms. Thus, it is suggested that in those systems of metal and environment where the conditions are between those for general dissolution and complete inactivity, localised corrosion and stress may act conjointly to promote crack extension by selective attack upon compositional or structural features pre-existing in the metal, by the stress exposing relatively small areas of bare, reactive metal or by adsorption of appropriate species at sites where the energy for fracture is thereby lowered. The implication is that a change in the composition or structure of the alloy or in the characteristics of the environment may result in a change in the mechanism of cracking and indeed, in some cases, that crack extension may be the result of more than one mechanism operating.