Research Papers: Materials and Fabrication

Evaluation of Fracture Toughness of a SA580 Gr. 3 Reactor Pressure Vessel Using a Bimodal Master Curve Approach

[+] Author and Article Information
Jong-Min Kim, Seok-Min Hong, Bong-Sang Lee

Safety Materials Technology
Development Division,
Korea Atomic Energy Research Institute,
111, Daedeok-Daero 989 Beon-Gil,
Daejeon 34057, Korea

Min-Chul Kim

Safety Materials Technology
Development Division,
Korea Atomic Energy Research Institute,
111, Daedeok-Daero 989 Beon-Gil,
Daejeon 34057, Korea
e-mail: mckim@kaeri.re.kr

1Corresponding author.

Contributed by the Pressure Vessel and Piping Division of ASME for publication in the JOURNAL OF PRESSURE VESSEL TECHNOLOGY. Manuscript received October 29, 2018; final manuscript received May 30, 2019; published online August 2, 2019. Assoc. Editor: Bostjan Bezensek.

J. Pressure Vessel Technol 141(6), 061403 (Aug 02, 2019) (8 pages) Paper No: PVT-18-1235; doi: 10.1115/1.4044263 History: Received October 29, 2018; Revised May 30, 2019

The standard master curve (MC) approach has a major limitation in that it is only applicable to homogeneous datasets. In nature, steels are macroscopically inhomogeneous. Reactor pressure vessel (RPV) steel has different fracture toughness with varying distance from the inner surface of the wall due to the higher cooling rate at the surface (deterministic material inhomogeneity). On the other hand, the T0 value itself behaves like a random parameter when the datasets have large scatter because the datasets are for several different materials (random inhomogeneity). In this paper, four regions, the surface, 1/8 T, 1/4 T, and 1/2 T, were considered for fracture toughness specimens of Korean Standard Nuclear Plant (KSNP) SA508 Gr. 3 steel to provide information on deterministic material inhomogeneity and random inhomogeneity effects. Fracture toughness tests were carried out for the four regions at three test temperatures in the transition region and the microstructure of each region was analyzed. The amount of upper bainite increased toward the center, which has a lower cooling rate; therefore, the center has lower fracture toughness than the surface so reference temperature (T0) is higher. The fracture toughness was evaluated using the bimodal master curve (BMC) approach. The results of the BMC analyses were compared with those obtained via a conventional master curve analyses. The results indicate that the bimodal master approach considering inhomogeneous materials provides a better description of scatter in the fracture toughness data than a conventional master curve analysis does.

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Wallin, K. , 1984, “ The Scatter in KIC-Results,” Eng. Fract. Mech., 19(6), pp. 1085–1093. [CrossRef]
Wallin, K. , 1999, “ The Master Curve: A New Method for Brittle Fracture,” Int. J. Mater., 12, pp. 342–354.
ASTM, 2010, “ Standard Test Method for Determination of the Reference Temperature, T0, for Ferritic Steels in the Transition Range,” ASTM International, West Conshohocken, PA, Standard No. E-1921-10.
Pous-Romero, H. , and Bhadeshia, H. K. D. H. , 2014, “ Continuous Cooling Transformations in Nuclear Pressure Vessel Steels,” Metall. Mater. Trans. A, 45(11), pp. 4897–4906. [CrossRef]
Pickering, E. J. , and Bhadeshia, H. K. D. H. , 2014, “ Macrosegregation and Microstructural Evolution in a Pressure-Vessel Steel,” Metall. Mater. Trans. A, 45(7), pp. 2983–2997. [CrossRef]
Hardin, T. C. , 2017, “ Carbon Macrosegregation in Large Forgings,” 29th Regulatory Information Conference, Rockville, MD, Mar. 16.
SINTAP, 1999, “ Structural Integrity Assessment Procedures for European Industry,” British Steel Report, Rotherham, UK, Report No. BE95-1426.
Wallin, K. , Nevasmaa, P. , Laukkanen, A. , and Planman, T. , 2004, “ Master Curve Analysis of Inhomogeneous Ferritic Steels,” Eng. Fract. Mech., 71(16–17), pp. 2329–2346. [CrossRef]
Sokolov, M. A. , and Tanigawa, H. , 2007, “ Application of the Master Curve to Inhomogeneous Ferritic/Martensitic Steel,” J. Nucl. Mater., 367, pp. 587–592. [CrossRef]
Viehrig, H. W. , Scibetta, M. , and Wallin, K. , 2006, “ Application of Advanced Master Curve Approaches on WWER-440 Reactor Pressure Vessel Steels,” Int. J. Pressure Vessels Piping, 83(8), pp. 584–592. [CrossRef]
Choi, S. B. , Choi, S. , Choi, J. B. , Chang, Y. S. , Kim, M. C. , and Lee, B. S. , 2012, “ Enhancement of Master Curve Methods for Inhomogeneous Material,” J. Mech. Sci. Technol., 26(9), pp. 2727–2734. [CrossRef]
ASTM, 2015, “ Standard Test Methods for Tension Testing of Metallic Materials,” Annual Book of ASTM Standards, ASTM International, West Conshohocken, PA, Standard No. E8/E8M-15.
Debarberis, L. , Sevini, F. , Acosta, B. , Kryukov, A. , Nikolaev, Y. , Amaev, A. D. , and Valo, M. , 2002, “ Irradiation Embrittlement of Model Alloys and Commercial Steels: Analysis of Similitude Behaviors,” Int. J. Pressure Vessels Piping, 79(8–10), pp. 637–642. [CrossRef]
Ballesteros, A. , Ahlstrand, R. , Bruynooghe, C. , von Estorff, U. , and Debarberis, L. , 2012, “ The Role of Pressure Vessel Embrittlement in the Long Term Operation of Nuclear Power Plants,” Nucl. Eng. Des., 243, pp. 63–68. [CrossRef]
Mccabe, D. E. , Merkle, J. G. , and Wallin, K. , 2005, “ An Introduction to the Development and Use of the Master Curve Method,” ASTM International, West Conshohocken, PA.
IAEA, 2005, “ Guidelines for Application of the Master Curve Approach to Reactor Pressure Vessel Integrity in Nuclear Power Plants,” International Atomic Energy Agency, Vienna, Austria, Report No. 429.


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Fig. 1

Investigated RPV block and locations of specimen extraction

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Fig. 2

OM and SEM images according to position

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Fig. 3

Variation of yield strength over the temperature range from room temperature to 196 °C

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Fig. 4

Standard MC reference temperature T0

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Fig. 5

Standard MC and measured KJC values at the surface

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Fig. 6

Standard MC and measured KJC values at 1/2 T and 1/4 T

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Fig. 7

Comparison of the bimodal and conventional MC analyses for all datasets corresponding to temperature dependence

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Fig. 8

Comparison of the bimodal and conventional MC analyses at various temperatures: (a) T = −100 °C, (b) T = −110 °C, and (c) T = −120 °C

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Fig. 9

Standard and bimodal MC with all measured KJC values



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