The effects of environments on the nucleation and growth of fatigue cracks were highlighted in previous chapters. These discussions touched upon the influence of oxygen-containing media on the kinematic irreversibility of cyclic slip (Chapter 4), crack initiation at corrosion pits (Chapter 4), the formation of brittle fatigue striations (Chapter 10), the role of fracture surface oxidation in promoting crack closure in constant amplitude and variable amplitude fatigue (Chapter 14), and the apparently anomalous growth of ‘chemically short’ fatigue cracks (Chapter 15). It is clear from these earlier descriptions that the usually deleterious (and occasionally beneficial) effects of environment must constitute an integral part of any complete mechanistic theory or design methodology for fatigue fracture.

This chapter deals specifically with the effects of environment on fatigue behavior. The discussions are presented in two parts: corrosion-fatigue effects and creep-fatigue effects. The first part begins with a survey of the micromechanisms of corrosion fatigue. This is followed by examples which illustrate the effects of gaseous and aqueous media on fatigue failure for different mechanical conditions of cyclic loading. This section is concluded with a brief examination of models of corrosion fatigue. In the second part, factors influencing the creep-fatigue behavior of engineering alloys are considered and many life prediction models are discussed. Particular attention is devoted to the mechanisms of high temperature fatigue deformation and to the issues pertaining to the characterization of creep crack growth using different fracture mechanics parameters.