MICROBULGE TESTING APPLIED TO NEUTRON-IRRADIATED MATERIALS

Microbulge testing was conducted on several Fe-Ni-Cr alloys irradiated as 0.3 mm thick disks to 10 dpa at 603 and 773 K in the Oak Ridge Research Reactor. Miniature tensile tests were also performed on specimens of the same alloys irradiated concurrently. Good correlation between the tensile yield strength and the bulge yield load was observed in unirradiated specimens, however, the correlation was not simple for irradiated specimens. Good correlation was also observed between the ultimate tensile strength and the maximum bulge load. While irradiation produced a significant reduction in total elongation in the tensile test, irradiation caused only a small decrease in the deflection corresponding to the maximum bulge load compared to that observed on thinner disks used at earlier experiments. The results suggest that the thinner disk is better suited for ductility evaluations than the thicker disk. The area bounded by the load-deflection traces of the bulge tests shows a systematic variation with both alloy composition and irradiation condition which is not observed in the tensile data. It is anticipated that this parameter may prove useful in the evaluation of the materials' toughness.