Micro Structural Aspects of Unstable Crack Propagation in Ferritic Steels

Article Preview

Abstract:

Fracture of ferritic reactor pressure vessel steels is determined by temperature and specimen size. In low temperature fracture occurs by cleavage, with elevation of temperature and decrease of specimen size the ratio of ductile tearing prior to cleavage increases and, in the end, fracture will have a ductile character. There is a temperature interval where both fracture mechanisms are present. Hypothesis of the traditional (global) assessment method has been that the shift of the fracture toughness reference curves due to neutron irradiation is equal with the shift of the ductile-to-brittle transition temperature measured by the Charpy impact test. Local assessment approaches based on the „weakest link” statistical theory recommend the direct measurement of fracture mechanics parameters to structural integrity evaluation. The paper describes the main features of both global and local approaches, analyzing the micro structural aspects of the most known micromechanical models of local approach and drawing conclusions concerning their applicability.

You might also be interested in these eBooks

Info:

Periodical:

Materials Science Forum (Volumes 537-538)

Pages:

465-472

Citation:

Online since:

February 2007

Authors:

Export:

Price:

Permissions CCC:

Permissions PLS:

Сopyright:

© 2007 Trans Tech Publications Ltd. All Rights Reserved

Share:

Citation:

[1] Euro Fracture Toughness Data Base. Project No. MAT-CT-940080.

Google Scholar

[2] ASME Boiler and Pressure Vessel Code, Section III: Nuclear Power Plant Components, New York, (1995).

Google Scholar

[3] RCC-M, Design and construction rules for mechanical components of PWR nuclear power plants, EdF and Framatome, (2000).

Google Scholar

[4] KTA 3201. 2 Komponenten des Primärkreises von Leichtwasserreaktoren. Konstruktion und Berechnung, (1996).

Google Scholar

[5] PNAE G-7-002-86: Strength Calculations for Components and Pipelines of Nuclear Power Installations (in Russian), Energoatomizdat, Moscow, (1990).

Google Scholar

[6] Brumovsky M: Check of Master Curve application to embrittled RPVs of WWER type reactors. Int. J. Pressure Vessels and Piping, 79. 2002. pp.715-721.

DOI: 10.1016/s0308-0161(02)00074-1

Google Scholar

[7] Regulatory Guideline 3. 17 (draft): PTS Assessment of Reactor Pressure Vessel (in Hungarian). OAH, Budapest, (2005).

Google Scholar

[8] Ritchie R O, Knott J F and Rice J R: On the relationship between critical tensile stress and fracture toughness in mild steel. J. Mech. Phys. Solids, 21, 1973. pp.395-410.

DOI: 10.2172/4442244

Google Scholar

[9] Beremin F M: A local criterion for cleavage fracture of nuclear pressure vessel steel. Metallurgical Transactions, 14A, 1983. pp.2277-2287.

DOI: 10.1007/bf02663302

Google Scholar

[10] Wallin K, Saario T and Törrönen K: Statistical model for carbide induced brittle fracture in steel. Metal Science, 18, 1984. pp.13-16.

DOI: 10.1179/030634584790420384

Google Scholar

[11] Lin T, Evans A G and Ritchie R O: Statistical model of brittle fracture by transgranular cleavage. J. Mech. Phys. Solids, 34, 1986. pp.477-496.

DOI: 10.1016/0022-5096(86)90013-x

Google Scholar

[12] Mudry F: A local approach to cleavage fracture. Nucl. Eng. Design, 105, 1987. p.6576.

Google Scholar

[13] Anderson T L, Stienstra D and Dodds R H Jr: A Theoretical Framework for Addressing Fracture in the Ductile-Brittle Transition Region. In: Landes J D, McCabe D E and Boulet J A M (eds) Fracture Mechanics: Twenty-Fourth Volume, ASTM STP 1207, Philadelphia, 1994. pp.186-214.

DOI: 10.1520/stp13706s

Google Scholar

[14] Balleteros A, Bros J and Brumovsky M: Applications of the Master Curve Approach to Irradiated Steels. In: Proc. 12th Int. Conf. Nucl. Engineering, Arlington, Virginia USA, 2004, ICONE12-49391.

DOI: 10.1115/icone12-49391

Google Scholar

[15] Guidelines for Application of the Master Curve Approach to Reactor Pressure Vessel Integrity in Nuclear Power Plants. TRS No. 429, International Atomic Energy Agency, Vienna, (2005).

Google Scholar

[16] Zhang X Z, Knott J F: Review and perspective on approaches of evaluating cleavage fracture toughness of pressure vessel steels. In: Proc. 12th Int. Conf. Nucl. Engineering, Arlington, Virginia USA, 2004, ICONE12-49053.

DOI: 10.1115/icone12-49053

Google Scholar

[17] Zhang X Z, Knott J F: The Statistical Modelling of Brittle Fracture in Homogeneous and Heterogeneous Steel Microstructures. Acta mater. 48, 2000. pp.2135-2146.

DOI: 10.1016/s1359-6454(00)00055-0

Google Scholar

[18] Ortner S: Factors affecting the shape of the ductile-to-brittle transition. Int. J. Pressure Vessels and Piping, 79, 2002. pp.693-700.

DOI: 10.1016/s0308-0161(02)00072-8

Google Scholar

[19] Margolin B Z et al: An engineering method for prediction of the fracture toughness temperature dependence for RPV steels. Int. J. Pressure Vessels and Piping, 80, 2003. pp.817-829.

DOI: 10.1016/j.ijpvp.2003.12.005

Google Scholar

[20] RD EO 0353-02: Methodology for Determination of RPV Service Life of VVER Reactors (in Russian), St. Petersburg-Moscow, (2000).

Google Scholar

[21] VERLIFE Unified procedure for lifetime assessment of components and piping in WWER NPPs. EC 5th FP, (2003).

DOI: 10.1115/pvp2004-2962

Google Scholar