How fatigue cracks grow, interact with microstructure, and lose similitude

摘要

This paper reviews the processes by which fatigue cracks grow and interact with applied load and microstructure. Faigure crack growth processes are remarkably similar irrespective of microstructure, crack size, or nature of the loading. Large strains at fatigue crack tips applied over repeated cycles severely altr, or homogenize, microstructures, follwed by crack advance. Microstructure affects fatigue crack growth kinetics more than growth processes. But, under marginal conditions, fatigue crack growth rates are also affected by microstructural features. Examples are small cracks growing under low stresses or large cracks growing near threshold.