Experimental and numerical investigations on the behaviour of cracks in X6 CrNi 18 11 under primary and secondary creep conditions

Results presented here show that the creep crack growth rate can be described, independent of geometry and specimen size, by the load parameter C* via an exponential law. A description by the stress intensity factor K, however, furnishes crack growth curves as a function of specimen size or specimen geometry. The interrelation via the determined exponential law corresponds to model conception assuming a plane stress condition. Finite element calculations of C*-calculations assuming a plane stress condition provide good descriptions of experimentally determined time histories of the displacements, V, and of the C*-integral. (orig./DG)