Strengthening and fracture in fatigue (approaches for achieving high fatigue strength)

Abstract

Three approaches to the problem of fatigue-resistant materials are reviewed and discussed. The macroparametric approach, which utilizes semiempirical equations to predict the effects of fracture stress, fracture ductility, and the cyclic strain-hardening exponent on fatigue, is useful for screening and selecting fatigue-resistant materials. The microstructural approach, which relates microstructure to the various stages of fatigue, is useful for designing new alloys and thermomechanical treatments to achieve fatigue resistance. The third approach utilizes fundamental deformation characteristics of materials to form a unifying rationale with which to describe fatigue behavior. Such concepts as slip-mode, stacking fault energy, and slip homogenization are discussed. Examples from the literature are cited to illustrate the degree of success which has been achieved with each approach. Some of the more promising future directions for developing fatigue resistance are also discussed.