Low cycle and thermomechanical fatigue of a copper alloy up to 850 °C

© Fraunhofer IWM

Copper alloys are often used in combustion chambers for aerospace applications where they are exposed to high mechanical and thermal loads. The material characterisation for these operating conditions is usually done by means of low cycle fatigue (LCF) and thermomechanical fatigue (TMF) tests. In a research project, a test set-up for LCF and TMF tests up to 850 °C was successfully developed. Particular attention was paid to the heating concept: For LCF tests, the samples are often heated by a high-temperature radiation furnace, for TMF tests, for which a fast heating and cooling rate is mandatory, the samples are typically heated by an induction heating system. However, this only works with ferromagnetic materials, which does not include copper. For this reason, a ferromagnetic susceptor is used, which is strongly heated and then transfers its heat to the specimen via radiation. Additional heat can be introduced via the specimen restraints. To exclude the influence of the environment, the tests could be carried out in an inert gas atmosphere. 


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