A study is reported about the successive stages encountered in the physical process leading to the fatigue failure of metals. It considers the metallurgical basis of the failure mechanisms in view of a direct utilization in life prediction methods. From the physical metallurgy point of view, it is well ascertained that several successive stages must be taken into account in order to follow a fatigue crack from its origin - usually occurring at the surface - to the final fracture of the material. At least, a nucleation stage followed by a propagation one has to be assumed in order to interpret the microscopical observations. However, there appears to be no general agreement, by the different investigators, for a clear-cut demarcation point, even if the two mentioned stages are often taken into account. Thus, after interpreting various groups of experimental data, some laws have been proposed by several authors, for obtaining a quantitative separation of the two successive stages. Here, these proposed laws have undergone a critical analysis which appears to be necessary for verifying their possible use as an evaluation of the nucleation stage in suitable life prediction methods.

Nucleation and propagation stages in fatigue life prediction / F.Pratesi; G.Zonfrillo; A.Del Puglia. - In: MATERIALS ENGINEERING. - ISSN 1120-7302. - STAMPA. - vol.1, n.1:(1990), pp. 301-308.

Nucleation and propagation stages in fatigue life prediction

PRATESI, FRANCO;ZONFRILLO, GIOVANNI;DEL PUGLIA, ALDO
1990

Abstract

A study is reported about the successive stages encountered in the physical process leading to the fatigue failure of metals. It considers the metallurgical basis of the failure mechanisms in view of a direct utilization in life prediction methods. From the physical metallurgy point of view, it is well ascertained that several successive stages must be taken into account in order to follow a fatigue crack from its origin - usually occurring at the surface - to the final fracture of the material. At least, a nucleation stage followed by a propagation one has to be assumed in order to interpret the microscopical observations. However, there appears to be no general agreement, by the different investigators, for a clear-cut demarcation point, even if the two mentioned stages are often taken into account. Thus, after interpreting various groups of experimental data, some laws have been proposed by several authors, for obtaining a quantitative separation of the two successive stages. Here, these proposed laws have undergone a critical analysis which appears to be necessary for verifying their possible use as an evaluation of the nucleation stage in suitable life prediction methods.
vol.1, n.1
301
308
F.Pratesi; G.Zonfrillo; A.Del Puglia
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/2158/359349
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