Advanced Materials Modelling for Structures by Holm Altenbach & Serge Kruch

Author:Holm Altenbach & Serge Kruch
Language: eng
Format: epub
Publisher: Springer Berlin Heidelberg, Berlin, Heidelberg

The analyses of experimental creep data on 2014 alloy forgings demonstrated that both the creep strength and the creep ductility at relatively high stress levels, such as those experienced by the material zone ahead the tip of a propagating crack, are strongly affected by the time previously spent at high temperature. These experimental observations can be used to adapt the model to the more general case of age hardenable alloys, taking into account overaging effects. The idea is to substitute the uniaxial local creep rupture strain () and time to rupture ( (the ratio of which defines the average creep strain rate) with their correlations to equivalent times spent at the reference temperature. Taking into account (), Fig. 4b suggests the power-law correlation to the total equivalent time to rupture . Further, the effects of material ovaraging on can be taken into account by simply considering as the sum of a part related to the time spent at high temperature by the component during its life (or by the CT specimen during the test, ) and of a constant contribution related to the initial heat treatment (). The description of equivalent creep rupture times of an overaged material can be obtained combining the power-law equation , fitting experimental data in Fig. 2, to Eq. (2), where and are substituted by and :

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