REVIEW OF FRACTOGRAPHIC ANALYSIS METHODS FOR FATIGUE FRACTURE SURFACES.
COLUMBIA UNIV NEW YORK INST FOR THE STUDY OF FATIGUE AND RELIABILITY
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Macro- and microfractographic methods and their application to fatigue studies are discussed. Macrofractography magnification less than x40 is useful in the examination of service failures, research on the effects of weld defects, and in program testing. Observation of fracture surfaces with the aid of high power light microscopes and electron microscopes is called microfractography. Fatigue striations have been closely studied using this method. Each of these striations is caused by a single load cycle, though several exceptions are discussed. Various other surface features, not connected with the fatigue process, but similar in appearance to striations are also described. Several models of the not well understood mechanism of striation formation are presented. Fractographic studies of striations are shown to be useful in the quantitative evaluation of crack propagation curves, cumulative damage, interaction effects, and service failures. Author
- Metallurgy and Metallography