Fundamentals of Corrosion Fatigue Behavior of Metals and Alloys.

It is well known that environment plays a very important role in fatigue failures. In some cases only crack propagation rates are affected however, for many others all of the steps leading to failure, pre-initiation deformation, crack initiation and crack propagation are affected. For still other cases, only the crack initiation and early propagation processes are affected. This paper attempts to evaluate the mechanisms which have been proposed for environmental effects on the early stages of fatigue damage, including crack initiation and early propagation in gaseous and in aqueous environments. Evidence is presented which indicates that there is no unifying theory of environmental fatigue, but that each alloyenvironment couple may exhibit significantly different behavior, depending on factors such as thermodynamics and kinetics as well as microstructure, slip character, etc. Author