Master Curve characterization of the fracture toughness in unirradiated and irradiated RPV steels using full- and 1/3-size pre-cracked Charpy specimens

Cleavage initiation fracture toughness (K-JC) tests have been performed wit h full-size (10 X 10 X 55 mm(3)) and 1/3-size (3.3 x 3.3 x 18.3 mm(3)) pre- cracked Charpy (PCVN) specimens in the transition temperature region. IAEA reference reactor pressure vessel (RPV) steels, JRQ and JFL, and Korean SA5 08-3 forging steels were used in this study. Some specimens were irradiated to a neutron fluence of 4.5 X 10(19) n/cm(2) (E > 1 MeV) at 288 degreesC. For the JRQ steel,, the transition temperature shift (DeltaT(0)) due to neu tron irradiation is about 134 degreesC from PCVN testing, which is greater than DeltaT(4IJ) from the conventional Charpy impact testing. However, in a modern RPV steel, the transition temperature shift was almost negligible. The reference temperatureT(0) values showed some dependence on the test tem perature and specimen geometry, while the median and probabilistic bound li nes of the Master Curve well described the population of the measured fract ure toughness data. In general, the deviation of the measured T-0 values fr om different test conditions was about 10-15 degreesC. Compared with the fu ll-size PCVN data, the 1/3-size PCVN specimens may also give a reasonable r esult if the test conditions are adequately selected. (C) 2000 Elsevier Sci ence Ltd. All rights reserved.