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Ansprechpartner

Dr. Ermile Gaganidze

ermile gaganidze does-not-exist.kit edu

Telefon +49 721 608 24083


Beteiligte Mitarbeiter

Dipl.-Ing. Stefan Knaak

Fracture-mechanical characterization of Tungsten and Tungsten-alloys considering the influence of texture and loading rate

Objectives
Universal testing machine
Universal testing machine with vacuum furnace and three-point bending setup

The inherent low fracture toughness of tungsten combined with the high ductile-to-brittle transition temperature (DBTT) are major drawbacks for structural application of tungsten alloys. Furthermore, fracture mechanical properties are expected to exhibit strong anisotropy due to (i) different grain shape/orientation with respect to the rolling direction and (ii) texture. The current task aims at characterization of different laboratory and industry scale W-alloys (W-Ti, W-V, W-Ta) in the interesting temperature window for fusion applications (RT up to 1300°C). Emphasis is put on the investigation of microstructure and loading rate dependence of the fracture toughness (KIC) and the DBTT.


Equipment and Methods
  • Fracture mechanical tests are conducted in three-point bending over a wide temperature range of 150°C to 1000°C at varied loading rates
  • High temperature experiments are performed in a universal testing machine equipped wit a vacuum furnace
  • Microstructural characterization by TEM, SEM and EBSD
  • Fractographic investigations by SEM and EBSD to gain insight into the responsible fracture mechanisms and the influence of the microstructure on the fracture process
 
 
REM EBSD
Example for the application of the EBSD method in fractographic studies. Left: SEM image of a notched tungsten specimen tested at 350°C. Right: EBSD measurements performed before and after the experiment. By combining the information of both measurements the observed crack path (white line) can be linked to the microstructure

 

Publication

E. Gaganidze, D. Rupp, J. Aktaa, Fracture behaviour of polycrystalline tungsten, Journal of Nuclear Materials 446 (2014) 240-245, http://dx.doi.org/10.1016/j.jnucmat.2013.11.001