The fracture toughness master curve shows the relationship between the median of fracture toughness and temperature in the ductile–brittle transition temperature region of ferritic steels such as reactor pressure vessel (RPV) steels. The master curve approach specified in the ASTM standard theoretically provides the confidence levels of fracture toughness in consideration with the inherent scatter of fracture toughness. The authors have conducted several fracture toughness tests for typical Japanese RPV steels with various specimen sizes and shapes and ascertained that the master curve can be accurately applied to the specimens with a thickness of 0.4-in. or larger. With respect to using the master curve method with the current surveillance program for operating RPVs, the utilization of miniature specimens is important. Miniature specimens, which can be taken from the broken halves of surveillance specimens, are necessary for the efficient determination of the master curve from the limited volume of the available materials. In this study, fracture toughness tests were conducted for typical Japanese RPV steels, particularly SFVQ1A forged and SQV2A plate materials, using the miniature C(T) specimens with a thickness of 4 mm, following the procedure in the ASTM standard. The results show that the differences in the test temperature, evaluation method, and specimen size did not affect the master curves, and the fracture toughness indexed by the reference temperature, To, obtained from miniature C(T) specimens were consistent with those obtained from the standard and larger C(T) specimens. It was also found that valid reference temperatures can be determined with a realistic number of miniature C(T) specimens, i.e., less than ten, if the test temperature was appropriately selected. Thus, the master curve method using miniature C(T) specimens could be a practical method to determine the fracture toughness of actual RPV steels.
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e-mail: miura@criepi.denken.or.jp
e-mail: soneda@criepi.denken.or.jp
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April 2012
Research Papers
Evaluation of Fracture Toughness by Master Curve Approach Using Miniature C(T) Specimens
Naoki Miura,
e-mail: miura@criepi.denken.or.jp
Naoki Miura
Materials Science Research Laboratory, Central Research Institute of Electric Power Industry
, 2-6-1 Nagasaka, Yokosuka-shi, Kanagawa 240-0196, Japan
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Naoki Soneda
e-mail: soneda@criepi.denken.or.jp
Naoki Soneda
Materials Science Research Laboratory, Central Research Institute of Electric Power Industry
, 2-6-1 Nagasaka, Yokosuka-shi, Kanagawa 240-0196, Japan
Search for other works by this author on:
Naoki Miura
Materials Science Research Laboratory, Central Research Institute of Electric Power Industry
, 2-6-1 Nagasaka, Yokosuka-shi, Kanagawa 240-0196, Japan
e-mail: miura@criepi.denken.or.jp
Naoki Soneda
Materials Science Research Laboratory, Central Research Institute of Electric Power Industry
, 2-6-1 Nagasaka, Yokosuka-shi, Kanagawa 240-0196, Japan
e-mail: soneda@criepi.denken.or.jp
J. Pressure Vessel Technol. Apr 2012, 134(2): 021402 (9 pages)
Published Online: January 11, 2012
Article history
Received:
September 12, 2010
Revised:
October 14, 2011
Accepted:
October 16, 2011
Online:
January 11, 2012
Published:
January 11, 2012
Citation
Miura, N., and Soneda, N. (January 11, 2012). "Evaluation of Fracture Toughness by Master Curve Approach Using Miniature C(T) Specimens." ASME. J. Pressure Vessel Technol. April 2012; 134(2): 021402. https://doi.org/10.1115/1.4005390
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