Fracture toughness testing on ferritic alloys using the electropotential technique

Abstract

Fracture toughness measurements as done conventionally require large specimens (5×5×2.5 cm) which would be prohibitively expensive to irradiate over the fluence and temperature ranges required for first wall design. To overcome this difficulty a single specimen technique for J integral fracture toughness measurements on miniature specimens (1.6 cm OD × 0.25 cm thick) was developed. Comparisons with specimens three times as thick show that the derived JIC is constant, validating the specimen for first wall applications. The electropotential technique was used to obtain continuous crack extension measurements, allowing a ductile fracture resistance curve to be constructed from a single specimen. Fracture toughness test results for HT-9 and 9Cr-lMo from 25-539°C are presented to illustrate the technique. © 1981.