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Dr.-Ing. Mario Walter

mario walter does-not-exist.kit edu

Telefon +49 721 608 23753

Beteiligte Mitarbeiter

Steffen Kohnle

Investigation of the thermo-mechanical fatigue behaviour of ferritic-martensitic steels

TMF test procedures
TMF test procedures

So called RAFM (Reduced Activation Ferritic Martensitic) steels are potential candidates for structural materials (first wall components) of future fusion reactors. Due to the predominant thermo-mechanical loading of relevant components under operating conditions there is an important need to characterize the creep-fatigue behavior of new developed materials like EUROFER97.

Within the scope of this project the thermo-mechanical fatigue (TMF) behaviour of RAFM steels will be investigated in application relevant temperature ranges. Metallographic investigations will be used in order to correlate damage evolutions with microstructural changes. In addition to basic TMF experiments tests with defined dwell times will be carried out to determine the influence of creep damage on the lifetime of the materials.

To perform the experiments specifically developed mechanical fatigue testing machines will be used.
Based on a resistance heater system the experimental setups facilitate tests under simultaneous temperature and mechanical load control. Although RAFM steels have higher chrome contents (9-12%) they are not corrosion proof. To investigate the influence of oxidation processes on the micro-crack propagation and according to this on the lifetime one testing machine is equipped with a high vacuum chamber.

TMF test facility with vacuum chamber
TMF test facility with vacuum chamber

Results from comparable LCF / TMF tests on EUROFER97

In general TMF experiments are difficult to perform and relatively time-consuming. Thus, selected low cycle fatigue (LCF) experiments will be conducted in order to determine whether TMF lifetimes can be predicted based on LCF investigations.


Current sub-project(s):

Investigations to the deformation, damage and failure behaviour of EUROFER 97 under thermo-mechanical cyclic loading