Considerations for metallographic observation of ... · INTERGRANULAR ATTACK IN ALLOY 600 STEAM GENERATOR TUBES DO HAENG HUR*, MYUNG SIK CHOI, DEOK HYUN LEE, and JUNG HO HAN Korea
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Nu c l E n g T e c h n o l 4 7 ( 2 0 1 5 ) 9 3 4e9 3 8
Fig. 3 e Morphology change of intergranular attack region on the transverse cross section of tube by forcing with a Vickers
hardness indenter. (A) Before indentation and (B) after indentation.
Fig. 4 e Fracture surface. (A) Intergranular attack and (B) primary water stress corrosion crack.
Nu c l E n g T e c h n o l 4 7 ( 2 0 1 5 ) 9 3 4e9 3 8 937
expanded before sectioning to the axial direction for metal-
lographic examination.
4. Conclusions
It was found that an IGA tube was crazed along the grain
boundaries into various types and directions through a
deformation from an applied stress. The direction and extent
of the crazing depended on those of the applied stress. It was
clearly shown that an IGA could be misevaluated as an SCC.
Therefore, it is recommended that a section of pulled tube be
hydraulically or pneumatically expanded for an exact evalu-
ation of the IGA defect in steam generator tubes.
Conflicts of interest
All authors have no conflicts of interest to declare.
Acknowledgments
Thisworkwas supportedby theNational Research Foundation
of Korea (NRF) grant funded by the Korea government (MSIP).
r e f e r e n c e s
[1] J.A. Gorman, J.P.N. Paine, M.J. Partridge, D.B. Lowenstein,Secondary Side Intergranular Attack and Stress CorrosionCracking, in: J.P.N.Paine (Ed.), SteamGeneratorReferenceBook,Rev.1, Vol. 2, Electric Power Research Institute, Palo Alto, CA,1994, pp. 12.1e12.75. TR-103824.
[2] D.W. Diercks, W.J. Shack, J. Muscara, Overview of steamgenerator tube degradation and integrity issues, Nucl. Eng.Design 194 (1999) 19e30.
[3] F. Cattant, Lessons learned from the examination of tubespulled from Electricite de France steam generators, Nucl.Eng. Design 168 (1997) 241e253.
[4] A. Stutzmann, F. Nordmann, Studies of IGA intergranularattack/stress corrosion cracking related parameters andremedies, Nucl. Eng. Design 162 (1996) 167e174.
[5] D.H. Hur, D.H. Lee, M.S. Choi, M.H. Song, J.H. Han, Rootcauses of intergranular attack in an operating nuclear steamgenerator tube, J. Nucl. Mater. 375 (2008) 382e387.
[6] P.M. Scott, P. Combrade, Corrosion in PressurizedWaterReactors, in:Corrosion:EnvironmentsandIndustries,Vol. 13C,ASM International, Materials Park, OH, 2006, pp. 362e385.
[7] G.S. Was, V.B. Rajan, The mechanism of intergranularcracking of Ni-Cr-Fe alloys in sodium tetrathionate,Metallurg. Trans. A 18A (1987) 1,313e1,323.
[8] Z. Fang, R.W. Staehle, Effects of the valence of sulfur onpassivation of Alloy 600, 690, and 800 at 25�C and 95�C,Corrosion 55 (1999) 355e379.
Nu c l E n g T e c h n o l 4 7 ( 2 0 1 5 ) 9 3 4e9 3 8938
[9] P. Scott, M. Le Calvar, Some possible mechanisms ofintergranular stress corrosion cracking of Alloy 600 in PWRprimary water, in: Proceedings of the 6th InternationalSymposium on Environmental Degradation of Materials inNuclear Power Systems e Water Reactors, The Minerals,Metals & Materials Society, San Diego, CA, 1993, pp.657e668.
[10] G.S. Was, H.H. Tischner, R.M. Latanision, The influence ofthermal treatment on the chemistry and structure of grainboundaries of Inconel 600, Metallurg. Trans. A 12A (1981)1,397e1,408.
[11] G.P. Airey, Microstructural characterization of Inconel Alloy600 annealed in the 700 to 1,200℉ temperature range,Corrosion 41 (1985) 2e10.
[12] C.L. Briant, C.S. O'Toole, E.L. Hall, The effect ofmicrostructure on the corrosion and stress corrosioncracking of Alloy 600 in acidic and neutral environments,,Corrosion 42 (1986) 15e27.
[13] P.J. Millett, PWR Molar Ratio Control Application Guidelines,Vol. 1, Electric Power Research Institute, Palo Alto, CA, 1995.TR-104811eV1.
[14] A. McIlree, Oxide-film Compositions on Alloy 600 Tubes fromSteam Generators, TR-104066, Electric Power ResearchInstitute, Palo Alto, CA, 1998.
[15] G.P. Airey, F.W. Pement, A Comparison of IntergranularAttack in Inconel Alloy 600 Observed in the Laboratory and inOperating Steam Generators, Corrosion. 82, Paper No. 205,NACE International, Houston, TX, 1982.