Comparison of impact test results on small and ISO-V type Charpy specimens

The ductile-to-brittle transition temperatures were calculated from the impact energies measured on ISO-V and KLST specimens for some non-irradiated, irradiated and both irradiated and annealed quenched and tempered pressure vessel steels at the proposed energy levels 68 J/41 J and 3.1 J/1.9 J, or 28 J and 3.15 J. At the energy levels derived from the mean upper shelf energy (USE) ratio (3.1 J/1.9 J) the transition temperatures were on the average 64 deg. C lower as compared with those measured on the ISO-V specimen. At the energy level 3.15 J derived from the ligament area the transition temperature was on the average 36 deg. C lower than that measured on the ISO-V specimen. For both criteria the standard deviation of the correlation was about 15 deg. C. A procedure was also proposed for calculating the USE of ISO-V specimen from the value measured on the KLST specimen. The transition temperature shifts measured for the irradiated materials on the KLST specimen were up to 30 - 40 deg. C lower than those measured on the ISO-V specimens when the shifts were measured at the levels below 75% USE. The degrees of recovery measured on the KLST specimens were of the same order of magnitude or lower than those measured on the ISO-V specimens.