SYMPOSIA PAPER Published: 01 January 2000
STP15252S

Influence of the Mechanical Strain Amplitude on the In-Phase and Out-of-Phase Thermo-mechanical Fatigue Behaviour of NiCr22Co12Mo9

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In total strain controlled in-phase and out-of-phase thermo-mechanical fatigue (TMF) tests on NiCr22Co12Mo9 (Inconel 617, Nicrofer 5520 Co) with a maximum temperature of 1123 K, a minimum temperature of 473 K and different mechanical strain amplitudes the cyclic stress-strain response, the change of the microstructure and the development of damage were analysed. The initial values of the induced stress amplitudes and plastic strain amplitudes, and the amount of cyclic hardening increase with the total mechanical strain amplitude. The observed cyclic hardening results from strong dislocation-dislocation and dislocation-particle interactions during plastic deformation at lower temperatures the latter being enhanced by the precipitation of small semi-coherent carbides at elevated temperatures of the TMF cycles. For each type of TMF tests the lifetime behaviour can be adequately described by the combination of the relationships of Basquin and Coffin-Manson. At equal total mechanical strain amplitudes in-phase tests always yield smaller lifetimes than out-of-phase tests. The difference between the two types of TMF-tests rises with increasing lifetime. This behaviour is caused by different accumulation of creep damage which is favoured by tensile stresses at high temperatures.

Author Information

Kleinpass, B
Linde AG, Höllriegelskreuth, Germany
Lang, K-H
Institut für Werkstoffkunde I, Universität Karlsruhe (TH), Karlsruhe, Germany
Löhe, D
Institut für Werkstoffkunde I, Universität Karlsruhe (TH), Karlsruhe, Germany
Macherauch, E
Institut für Werkstoffkunde I, Universität Karlsruhe (TH), Karlsruhe, Germany
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Details
Developed by Committee: E08
Pages: 36–50
DOI: 10.1520/STP15252S
ISBN-EB: 978-0-8031-5423-0
ISBN-13: 978-0-8031-2853-8