Fatigue damage in metals is caused by the simultaneous action of cyclic stress, tensile stress, and plastic strain. This article details the fundamental aspects of the stages of the fatigue failure process. These include cyclic plastic deformation prior to fatigue crack initiation, initiation of one or more microcracks, propagation or coalescence of microcracks to form one or more microcracks, and propagation of one or more macrocracks.

This article discusses the microstructural processes that take place during plastic deformation and presents a plain phenomenological and general description of the cyclic stress-strain (CSS) response. It emphasizes the microstructural aspects of...