A flow instability criterion developed based on a continuum model was found to be related to the onset of power law breakdown in creep deformation mechanisms. The currently proposed flow instability criterion based on power law breakdown (n > 7, where n is the stress exponent) can be applied to any materials showing power law creep and power law breakdown without any assumptions and limitations. The proposed model also allows for the easy construction of power dissipation map because power dissipation efficiency can be explicitly expressed as a function of n even when n is not constant with strain rate.
