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Microstructural Characterization of Alloy 52 Narrow-Gap Dissimilar Metal Weld After Aging

  • Teemu SarikkaEmail author
  • Roman Mouginot
  • Matias Ahonen
  • Sebastian Lindqvist
  • Ulla Ehrnstén
  • Pekka Nevasmaa
  • Hannu Hänninen
Conference paper
Part of the The Minerals, Metals & Materials Series book series (MMMS)

Abstract

The safe-end dissimilar metal weld (DMW) joining the reactor pressure vessel to the main coolant piping is one of the most critical DMWs in a nuclear power plant (NPP). DMWs have varying microstructures at a short distance across the ferritic-austenitic fusion boundary (FB) region. This microstructural variation affects the mechanical properties and fracture behavior and may evolve as a result of thermal aging during long-term operation of an NPP. This paper presents microstructural characterization performed for as-manufactured and 5000 h and 10,000 h thermally aged narrow-gap DMW representing a safe-end DMW of a modern pressurized water reactor (PWR) NPP. The most significant result of the study is that the thermal aging leads to a significant decrease in a hardness gradient observed across the ferritic-austenitic FB of the as-manufactured DMW.

Keywords

Dissimilar metal weld Ni-base alloy Microstructural characterization Aging 

Notes

Acknowledgements

This study, carried out in parallel with that presented by Ahonen et al. on mechanical behavior, has been made in collaboration between Aalto University School of Engineering and VTT Technical Research Centre of Finland Ltd within the Nickel-base Alloy Welding Forum (NIWEL)-research project funded by TEKES, Finnish (Teollisuuden Voima Oyj and Fortum Oyj) and Swedish (Vattenfall AB and OKG AB) energy industry. The authors wish to express their gratitude for the funding and participation to the project.

References

  1. 1.
    D. Féron (ed.), Overview of Nuclear Materials and Nuclear Corrosion Science and Engineering. (Nuclear Corrosion Science and Engineering. Elsevier, 2012), pp. 31–56Google Scholar
  2. 2.
    D.D. MacDonald, G.A. Cragnolino, Corrosion of Steam Cycle Materials, ed by P. Cohen, ASME Handbook on Water Technology for Thermal Power Systems. ASME. pp. 659–1031Google Scholar
  3. 3.
    IAEA, Cost Drivers for the Assessment of Nuclear Power Plant Life Extension. IAEA-TECDOC-1309. (International Atomic Energy Agency, 2002), p. 84. ISBN 92-0-114402-4Google Scholar
  4. 4.
    Q. Peng, et al., SCC behavior in the transition region of an alloy 182-SA 508 Cl.2 dissimilar weld joint under simulated BWR-NWC conditions. in Proceedings of the 12th International Conference on Environmental Degradation of Materials in Nuclear Power Systems-Water Reactors, 2005 pp. 589–599Google Scholar
  5. 5.
    C.D. Lundin, Dissimilar metal welds-transition joints literature review. Welding J. 61(2), 58–63 (1982)Google Scholar
  6. 6.
    R. Rajeev et al., Origin of hard and soft zone formation during cladding of austenitic/Duplex stainless steel on plain carbon steel. Mater. Sci. Technol. 17(8), 1005–1011 (2001)CrossRefGoogle Scholar
  7. 7.
    T. Sarikka et al., Microstructural, mechanical, and fracture mechanical characterization of SA 508-alloy 182 dissimilar metal weld in view of mismatch state. Int. J. Press. Vessels Pip. 145, 13–22 (2016)CrossRefGoogle Scholar
  8. 8.
    C. Sudha et al., Systematic study of formation of soft and hard zones in the dissimilar weldments of Cr–Mo steels. J. Nucl. Mater. 302, 193–205 (2002)CrossRefGoogle Scholar
  9. 9.
    T.W. Nelson, el al., Investigation of boundaries and structures in dissimilar metal welds. Sci Technol Welding Joining. 3(5) 249–255 (1998)CrossRefGoogle Scholar
  10. 10.
    B.T. Alexandrov et al., Fusion boundary microstructure evolution associated with embrittlement of Ni-base alloy overlays applied to carbon steel. Welding World 57(1), 39–53 (2012)CrossRefGoogle Scholar
  11. 11.
    T. Sarikka, Effect of Strength Mismatch on Fracture Behavior of Ferrite-Austenite Interface in Ni-Base Alloy Dissimilar Metal Welds. Aalto University Publication Series. Doctoral Dissertations. p. 135. ISBN 978-952-60-6983-8Google Scholar
  12. 12.
    T.W. Nelson et al., Nature and evolution of the fusion boundary in ferritic-austenitic dissimilar metal welds—Part 1: Nucleation and growth. Welding J. 78, 329–337 (1999)Google Scholar
  13. 13.
    T.W. Nelson et al., Nature and evolution of the fusion boundary in ferritic-austenitic dissimilar metal welds—Part 2: on-cooling transformations. Welding J. 79, 267–277 (2000)Google Scholar
  14. 14.
    W.C. Chung et al., Microstructure and stress corrosion cracking behavior of the weld metal in alloy 52-A508 dissimilar welds. Mater. Trans. 52(1), 12–19 (2011)CrossRefGoogle Scholar
  15. 15.
    U. Ehrnstén, Corrosion and Stress Corrosion Cracking of Austenitic Stainless Steels. ed by T.R. Allen, R.E. Stoller, S. Yamanaka, eds. Comprehensive Nuclear Materials, vol 5, (Elsevier, 2012), pp. 93–104Google Scholar
  16. 16.
    S. Fyfitch, Corrosion and Stress Corrosion Cracking of Ni-base Alloys. ed by T.R. Allen, R.E. Stoller,S. Yamanaka, Comprehensive Nuclear Materials, vol 5, (Elsevier, 2012) pp. 69–92Google Scholar
  17. 17.
    P.M. Scott, Environment-Assisted Cracking in Austenitic Components. Int. J. Press. Vessels Pip. 65(3), 255–264 (1996)CrossRefGoogle Scholar
  18. 18.
    Z. Lu et al., Characterization of microstructure, local deformation and microchemistry in alloy 690 heat-affected zone and stress corrosion cracking in high temperature water. J. Nucl. Mater. 465, 471–481 (2015)CrossRefGoogle Scholar
  19. 19.
    B.E. Payne, Nickel-base welding consumables for dissimilar metal welding applications. Metal Construct. 1(12), 79–87 (1969)Google Scholar
  20. 20.
    F. Scenini, et al., Alloy Oxidation Studies Related to PWSCC. in Proceedings of the 12th International Conference on Environmental Degradation of Materials in Nuclear Power Systems-Water Reactors, 2005, pp. 891–902Google Scholar
  21. 21.
    P.L. Andresen, et al., Effects of PWR Primary Water Chemistry on PWSCC of Ni Alloys. in 13th International Conference on Environmental Degradation of Materials in Nuclear Power System, (Whistler, British Columbia, 2007) pp. 1–21Google Scholar
  22. 22.
    H.T. Lee, J.L. Wu, Intergranular corrosion resistance of nickel-based alloy 690 weldments. Corros. Sci. 52(5), 1545–1550 (2010)CrossRefGoogle Scholar
  23. 23.
    G. Sui et al., Stress corrosion cracking of alloy 600 and alloy 690 in hydrogen/steam at 380 °C. Corros. Sci. 39(3), 565–587 (1997)CrossRefGoogle Scholar
  24. 24.
    G.A. Young, et al., The Kinetics of Long Range Ordering in Ni-Cr and Ni-Cr-Fe Alloys. in Proceedings of the 16th Annual Conference on the Environmentally Assisted Cracking of Materials in Nuclear Power Systems-Water Reactors, 2013, pp. 1–22Google Scholar
  25. 25.
    P. Joly et al., Thermal Ageing Effects: Examples on Materials of PWR and Preventive Measures in the Design of EPR Plants (DOI, Materials Innovation for Nuclear Optimized Systems, 2013). doi: https://doi.org/10.1051/epjconf/20135104004 CrossRefGoogle Scholar
  26. 26.
    R. Mouginot, et al., Characterization of a Ni-base NG-DMW of Modern PWR. in International Symposium Fontevraud 8 on Contribution of Materials Investigations and Operating Experience to LWRs’ Safety, Performance and Reliability, (SFEN, Avignon, France, 2014), p. 14Google Scholar
  27. 27.
    R. Mouginot et al., Thermal ageing and short-range ordering of alloy 690 between 350 and 550 & #xB0;C. J. Nucl. Mater. 485, 56–66 (2017)CrossRefGoogle Scholar

Copyright information

© The Minerals, Metals & Materials Society 2019

Authors and Affiliations

  • Teemu Sarikka
    • 1
    Email author
  • Roman Mouginot
    • 1
  • Matias Ahonen
    • 2
  • Sebastian Lindqvist
    • 2
  • Ulla Ehrnstén
    • 2
  • Pekka Nevasmaa
    • 2
  • Hannu Hänninen
    • 1
  1. 1.Aalto University School of EngineeringAaltoFinland
  2. 2.VTT Technical Research Centre of Finland Ltd, VTTEspooFinland

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