Effects of specimen size reduction on the transition curve of the Charpy V-notch impact test

This study was undertaken to correlate the impact properties of ASTM standard full size Charpy V-notch impact specimens to the impact properties of subsize specimens. An ASTM A533-B quenched and tempered plate steel was examined. The fine grained martensitic material had a coarse prior austenite grain size, which resulted in a low upper shelf energy for this material. Three sizes of specimens were included. Specimens were irradiated in the TRIGA Reactor Facility operated by the U. S. Geological Survey in Denver, Colorado, to 1 x 1019 n/cm2 (E \u3e 1 MeV) at 150°C (302°F). Unirradiated and irradiated specimens were tested at several temperatures in an instrumented drop tower, and the load during impact was recorded as a function of time. Full transition curves of energy versus temperature were determined for the three sizes. The results are presented and compared. A method for correlating the upper shelf energies determined from subsize and full size specimens was developed. The method incorporated a normalizing factor proposed in earlier related studies, and the method is discussed in light of the new data. The estimates of upper shelf energy derived from the correlation agreed with the measured full size values within 10%. The correlation was found to be applicable to the subsize specimen data. The irradiation induced shift in the ductile to brittle transition temperature of the material was found to be independent of specimen size --Abstract, page iii