In recent years the role of strain rate as a key mechanics variable has been well accepted in the quantitative evaluation of certain environmentally influenced cracking processes of ductile alloys– especially those involving the conjoint action of stress and corrosion. The author had developed one such evaluation model for the intergranular stress corrosion cracking (IGSCC) in aqueous environments that addressed the question of time-to-failure in the prevalent sense of time to initiate an observable crack. The main objective of this paper is to extend the same underlying basic modeling concepts to address the crack growth versus time relation starting with a smooth surface. In particular, it is shown that the extension to analyze crack growth, at least until a sizable crack is grown, can be based on a consistent and unified implementation of the deformation mechanics relations in the form of an incremental damage formulation
After proposing the formulation, its application is presented for the commonly used constant extension rate test (CERT) on smooth specimens. Significant observations, such as the lowering of strain-at-failure and the increase of depth of IGSCC with the lowering of the applied strain rate, are shown to be correctly interpreted by the proposed formulation. It is suggested that the alternative interpretation of SCC data from smooth specimens can be useful, to a first approximation, in deriving crack growth rate information for the material-environment combination under consideration.
