Elevated temperature impact tests are performed to define the location of the upper shelf impact energy for materials. Beyond the upper shelf, impact tests are not that typical, and would provide limited information because of the rapid strain rates involved with Charpy impact testing.

I would recommend a hot tensile or notched hot tensile test and evaluate the loss of ductility (%RA) for the material in question. Certain nickel-base alloys can exhibit a loss of ductility commonly referred to as ductility dip cracking (DDC).