SHEAR PUNCH TESTING OF NI-59 ISOTOPICALLY-DOPED MODEL AUSTENITIC ALLOYS AFTER IRRADIATION IN FFTF AT DIFFERENT HE DPA RATIOS/

In this last of a series of papers describing the evolution of microst ructure, void swelling and mechanical properties of model austenitic a lloys in response to differences in helium/dpa rates, shear punch test ing is used to assess the relative effect of helium generation ratios and various important material and environmental variables. Shear punc h data confirm the general trends observed in earlier tensile data der ived from the Ni-59 isotopic doping experiment. There is a convergence to a common saturation level of yield strength that depends on alloy composition, temperature and displacement rate, but not on starting co ndition. The approach to saturation can be sensitive to helium/dpa rat io, however, and may depend on the starting state. For reasons not yet known, shear punch tests appear to be more sensitive to such transien t differences than are tensile tests. (C) 1998 Published by Elsevier S cience B.V. All rights reserved.