Advertisement

Effects of Thermal Aging and Low Dose Neutron Irradiation on the Ferrite Phase in a 308L Weld

  • Z. Li
  • Y. Chen
  • A. S. Rao
  • Y. YangEmail author
Conference paper
Part of the The Minerals, Metals & Materials Series book series (MMMS)

Abstract

The integrity of reactor internal components made of austenitic stainless steel welds with a duplex structure can potentially be affected by thermal aging and/or neutron irradiation induced embrittlement. There have not been sufficient studies on the long-term service performance of SS welds in light water reactors. In this study, thermal aging was performed at 400 °C for up to 2220 h on a 308L weld, and the irradiation was conducted in the Halden reactor at ~315 °C to 0.08 dpa (5.6 × 1019 n/cm2, E > 1 meV). The microstructural evolution of the ferrite phase was characterized using atom probe tomography (APT) and auxiliary transmission electron microscope studies. Spinodal decomposition and Ni-Mn-Si solute clusters were observed in both the thermally aged and neutron irradiated 308L welds. As compared with thermal aging, low dose neutron irradiation induced similar spinodal decomposition with slightly larger concentration wavelength and amplitude. The solute clusters in irradiated ferrite phase also show a larger mean size, a wider size distribution, but a lower number density as compared with those in thermally aged ferrite phase. In addition, the neutron irradiation significantly promotes segregation of trace elements, particularly phosphorus, at the Ni-Mn-Si solute clusters.

Keywords

Thermal aging Neutron irradiation Austenitic stainless steel weld 

Notes

Acknowledgements

This research was sponsored by the U. S. NRC under contract #NRC-HQ-14-G-0014. This work was also partially supported by the U.S. Department of Energy, Office of Nuclear Energy under DOE Idaho Operations Office Contract DE-AC07-051d14517, as part of an ATR National Scientific User Facility experiment. The authors would like to thank Joanna Taylor, Jatuporn Burns and Dr. Yaqiao Wu for their invaluable assistance at the CAES facility.

References

  1. 1.
    D.J. Alexander et al., U.S. nuclear regulatory commission (NUREG/CR-6628, 2000)Google Scholar
  2. 2.
    D.J. Gavenda et al., U. S. nuclear regulatory commission (NUREG/CR-6428, 1996)Google Scholar
  3. 3.
    T. Takeuchi et al., Microstructural changes of a thermally aged stainless steel submerged arc weld overlay cladding of nuclear reactor pressure vessels. J. Nucl. Mat. 425, 60–64 (2012)CrossRefGoogle Scholar
  4. 4.
    T. Takeuchi et al., Study on microstructural changes in thermally-aged stainless steel weld-overlay cladding of nuclear reactor pressure vessels by atom probe tomography. J. Nucl. Mat. 415, 198–204 (2011)CrossRefGoogle Scholar
  5. 5.
    J.S. Lee et al., Microstructural characteristic and embrittlement phenomena in neutron irradiated 309L stainless steel RPV clad. J. Nucl. Mater. 326, 38–46 (2004)CrossRefGoogle Scholar
  6. 6.
    T. Takeuchi et al., Effect of neutron irradiation on the microstructure of the stainless steel electroslag weld overlay cladding of nuclear reactor pressure vessels. J. Nucl. Mater. 443, 266–273 (2013)CrossRefGoogle Scholar
  7. 7.
    T.S. Byun, J.T. Busby, ORNL/LTR-2012/440, 2012Google Scholar
  8. 8.
    L. Yao et al., On the multiplicity of field evaporation events in atom probe: a new dimension to the analysis of mass spectra. Phil. Mag. Lett. 90, 121–129 (2010)CrossRefGoogle Scholar
  9. 9.
    B. Gault et al., Impact of directional walk on atom probe microanalysis. Ultramicroscopy 113, 182–191 (2012)CrossRefGoogle Scholar
  10. 10.
    J. Zhou et al., Concurrent phase separation and clustering in the ferrite phase during low temperature stress aging of duplex stainless steel weldments. Acta Mater. 60, 5818–5827 (2012)CrossRefGoogle Scholar
  11. 11.
    G. Bonny et al., On the α-α’ miscibility gap of Fe-Cr alloys. Scripta Mater. 59, 1193–1196 (2008)CrossRefGoogle Scholar
  12. 12.
    J. Zhou et al., Quantitative evaluation of spinodal decomposition in Fe-Cr by atom probe tomography and radial distribution function analysis. Microsc. Microanal. 19, 665–675 (2013)CrossRefGoogle Scholar
  13. 13.
    R.P. Kolli, D.N. Seidman, Comparison of compositional and morphological atom-probe tomography analyses for a multicomponent Fe-Cu steel. Microsc. Microanal. 13, 272–284 (2006)CrossRefGoogle Scholar
  14. 14.
    T. Takeuchi et al., Effects of thermal aging on microstructure and hardness of stainless steel weld-overlay claddings of nuclear reactor pressure vessels. J. Nucl. Mat. 452, 235–240 (2014)CrossRefGoogle Scholar
  15. 15.
    J.W. Cahn, On spinodal decomposition. Acta Metall. 9, 795–801 (1961)CrossRefGoogle Scholar
  16. 16.
    Y. Chen et al., Quantitative atom probe tomography characterization of microstructure in a proton irradiated 304 stainless steel. J. Nucl. Mater. 451, 130–136 (2014)CrossRefGoogle Scholar
  17. 17.
    F. Danoix, P. Auger, Atom probe studies of the F-Cr system and stainless steels aged at intermediate temperature: a review. Mater. Charact. 44 (2000)Google Scholar
  18. 18.
    F. Danoix et al., A 3D study of G-phase precipitation in spinodally decomposed α-ferrite by tomographic atom-probe analysis. Microsc. Microanal. Microstruct. 5, 121–132 (1994)CrossRefGoogle Scholar
  19. 19.
    F. Danoix et al., Hardening of aged duplex stainless steels by spinodal decomposition. Microsc. Microanal. 10, 349–354 (2004)CrossRefGoogle Scholar
  20. 20.
    T.R. Allen et al., The effects of low dose rate irradiation and thermal aging on reactor structural alloys. J. Nucl. Mater. 270, 290–300 (1999)CrossRefGoogle Scholar

Copyright information

© The Minerals, Metals & Materials Society 2019

Authors and Affiliations

  1. 1.Department of Materials Science and Engineering, Nuclear Engineering ProgramUniversity of FloridaGainesvilleUSA
  2. 2.Nuclear Engineering DivisionArgonne National LaboratoryLemontUSA
  3. 3.US Nuclear Regulatory CommissionRockvilleUSA

Personalised recommendations