SYMPOSIA PAPER Published: 01 January 2001

Master Curve Characterization of Irradiation Embrittlement Using Standard and 1/3-Sized Precracked Charpy Specimens


Cleavage initiation fracture toughness (KJC) tests have been performed in the transition temperature ranges of five different heats of reactor pressure vessel steels. The main purpose of this study is to investigate the applicability of the ASTM Standard Test Method for Determination of Reference Temperature, To, for Ferritic Steels in the Transition Range (E1921-97) to small specimens available in normal surveillance capsules. Precracked Charpy-type specimens with the standard size (10×10×55mm, PCVN) and 1/3-size (3.3×3.3×18.3mm, 1/3-PCVN) are mainly investigated. Results from more than 300 fracture toughness test data are presented including 120 unirradiated PCVN specimens and 100 unirradiated 1/3-PCVN specimens in addition to some CT specimen data and two sets of irradiated PCVN data. The test materials are the IAEA reference steels, so-called JRQ and JFL, and three Korean SA508-3 forging steels that were made by different refining processes. JRQ and a Korean steel, SKA-1, are also evaluated after neutron irradiation by PCVN specimens as well as Charpy impact tests. Fracture toughness data showed that the master curve and its probabilistic bound lines represent the population of the test data measured from different materials and specimens with good accuracy. However, there are still the effects of specimen geometry and size on the measured To values. These effects seem to be more significant in microscopically less homogeneous materials. Smaller bend type specimens may give slightly less conservative results than the larger CT type specimens. One of the important findings is that ultra small 1/3-PCVN specimens are also valuable as the standard size PCVN specimens for determining reference temperatures since the differences are rather systematic and predictable. The T28J correlation, based on the PCVN data only, works well for the current data sets including irradiated materials.

Author Information

Lee, B-S
Korea Atomic Energy Research Institute, Yusong, Taejon, Korea
Yang, W-J
Korea University, Seoul, Korea
Huh, M-Y
Korea University, Seoul, Korea
Chi, S-H
Korea Atomic Energy Research Institute, Yusong, Taejon, Korea
Hong, J-H
Korea Atomic Energy Research Institute, Yusong, Taejon, Korea
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Developed by Committee: E10
Pages: 55–67
DOI: 10.1520/STP10525S
ISBN-EB: 978-0-8031-5454-4
ISBN-13: 978-0-8031-2878-1