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Ansprechpartner
Dr.-Ing. Mario Walter

mario walter does-not-exist.kit edu

Telefon +49 721 608 23753


Beteiligte Mitarbeiter

Steffen Kohnle

Ralf Dahm

Investigation of the isothermal low cycle fatigue behavior of metallic structural materials for future fusion reactors

So called RAFM (Reduced Activation Ferritic Martensitic) steels and refractory metals like tungsten and tungsten alloys, respectively, are potential candidates for structural materials (first-wall and divertor components) of future fusion reactors.

Due to the predominant thermo-mechanical loading of relevant components under operating conditions it is critical to characterize the fatigue as well as the creep-fatigue behavior of newly developed materials.

Within the scope of this project the isothermal low cycle fatigue (LCF) behavior of newly developed RAFM steels and tungsten alloys will be investigated. In addition to basic LCF experiments at application relevant temperatures multi-step tests will be performed to study the behavior of the materials under alternating load conditions during one test. Furthermore, tests with defined dwell times will be carried out to determine the influence of creep damage on the fatigue lifetime of the materials.

LCF multi-step test procedures LCF multi-step test procedures
LCF multi-step test procedures

LCF dwell time test procedures
Test procedures
To perform the experiments servohydraulic testing machines (MTS) equipped with quad elliptical heater chambers (Tmax = 850°C) and electromechanical testing machines (Instron) equipped with high temperature-high vacuum (HT-HV) chambers (tungsten radiation heater, Tmax = 1600°C) will be used. Currently a new HT-HV facility based on a servohydraulic testing machine equipped with a induction heater (Tmax = 2000°C) is being built.
 

Electromechanical testing machine with HT-HV chamber   Universal servohydraulic testing machine with a quad elliptical heating chamber
Electromechanical testing machine with HT-HV chamber   Universal servohydraulic testing machine with a quad elliptical heating chamber

Accompanying the tests on standard specimens tests on small specimens will be performed to determine possible size effects. Also tests on specimens with welded joints (especially diffusion welded joints) will be conducted in order to determine the influence of joining seams on the lifetime of components.

 

LCF
Results of investigations regarding the influence of specimen size and joining seams on the lifetime of EUROFER 97 under isothermal cyclic loading