Pre-normative research work

Comparative measurements using thermocouples (TCs) of several chemical compositions (Pt-PtRh, Ni-CrNi, Ni-NiAl, etc.), various configurations of attachment (ribbon type, spot welded, coaxial embedded) and different wire 

4 Temperature-time path for ribbon-type and spot-welded thermocouples. 

To investigate the possibility of temperature control without any TCs applied within the gauge length, a spot-welded TC was placed at the specimen shank. The setpoint program was adjusted in a way that temperature-time paths with = 400°C, = 850°C and constant heating and cooling 

5 Dynamic temperature control by thermocouples spot welded at the specimen shoulder. 

Errors of the temperature path affect the cyclic deformation and lifetime behaviour in TMF and, therefore, lead to incorrect results, because plastic deformation is altered, oxidation processes are accelerated/decelerated and even undesired phase changes may be induced, if the temperature exceeds the target values. These influences, which are primarily dependent on the material as well as on the TMF temperature cycle, cannot be assessed by simple theoretical arguments, since they will interact, in general, in a complex way. 

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