Review of Fatigue Crack Growth in Metallics at Low Stress Intensities.

摘要

This review is concerned with the fatigue crack growth response of metallics at low stress intensities. In particular the fatigue threshold e.g. the stress intensity at which cracks can arrest is considered in detail. The fatigue crack growth rates and the fatigue threshold stress intensity delta K/th are considered in relation to the following variables, mean stress, yield stress, test temperature, test frequency, fatigue crack closure, microstructure, environment and crack length. The mechanisms, models and formulations derived to represent fatigue crack growth at low stress intensities and the fatigue threshold are also reviewed. The measurement of fatigue crack growth rates and fatigue thresholds is outlined and the desirability of obtaining delta K/eff data is highlighted. The main characteristics of aluminum alloys, steels and titanium alloys with respect to fatigue crack growth and fatigue thresholds are presented. A conservative view of the fog resistance of metals and alloys is developed which allows the identification of the minimum fatigue threshold and maximum fog rates that can be experienced for a particular set of test conditions. (Author)