Transactions of the Korean Society of Pressure Vessels and Piping (한국압력기기공학회 논문집)

Korean Society of Pressure Vessels and Piping (한국압력기기공학회)
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Effect of long-term thermal aging on the microstructural and mechanical characteristics of nickel-based alloy weldment

니켈계 합금 용접부의 미세조직 및 기계적 특성에 대한 장기 열적 시효의 영향

  • 유승창 (울산과학기술원, 원자력과학 및 공학과) ;
  • 함준혁 (울산과학기술원, 원자력과학 및 공학과) ;
  • 김지현 (울산과학기술원, 원자력과학 및 공학과)
  • Received : 2016.05.24
  • Accepted : 2016.06.14
  • Published : 2016.06.30
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Abstract

To investigate the effect of long-term thermal aging on the microstructural and mechanical characteristics of weldment made of nickel base alloy and its weld metal, an accelerated heat treatment was applied to simulate the process of long-term thermal aging in the operating condition of nuclear power plant. A representative nickel-based weldment with Alloy 600 and Alloy 182 was fabricated and heat-treated at $400^{\circ}C$ for 1,713 h and 3,427 h to simulate the thermal aging for the period equivalent to 15 and 30 years in operating pressurized water reactors, respectively. The microstructural and mechanical characteristics were analyzed by using optical microscopy, scanning electron microscopy and Vickers microhardness measurement. Changes were observed in precipitation behavior and microhardness of each specimen, and these changes were mainly attributed to the change in precipitated morphology and residual stress across the weld during the thermal aging process.

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References

  1. Kim, J.H. and Ballinger, R.G., 2008, "Stress Corrosion Cracking Crack Growth Behavior of Type 316L Stainless Steel Weld Metals in Boiling Water Reactor Environments", Corrosion, Vol. 64, pp. 645-656. https://doi.org/10.5006/1.3279925
  2. Choi, K.J., Kim, J.J., Lee, B.H., Bahn, C.B. and Kim, J.H., 2013, "Effects of thermal aging on microstructures of low alloy steel-Ni base alloy dissimilar metal weld interfaces", J. Nucl. Mater., Vol. 441, pp. 493-502. https://doi.org/10.1016/j.jnucmat.2013.07.003
  3. Scott, P., 2007, "An overview of materials degradation by stress corrosion in PWRs", EUROPEAN FEDERATION OF CORROSION PUBLICATIONS, Vol. 51, pp. 3-14.
  4. Andresen, P.L. and Morra, M.M., 2008, "Stress Corrosion Cracking of Stainless Steels and Nickel Alloys in High-Temperature Water", Corrosion, Vol. 64, pp. 15-29. https://doi.org/10.5006/1.3278457
  5. Hou, J., Peng, Q., Takeda, Y., Kuniya, J. and Shoji, T., 2010, "Microstructure and stress corrosion cracking of the fusion boundary region in an alloy 182-A533B low alloy steel dissimilar weld joint", Corros. Sci., Vol. 52, pp. 3949-3954. https://doi.org/10.1016/j.corsci.2010.08.002
  6. Shoji, T., Lu, Z. and Murakami, H., 2010, "Formulating stress corrosion cracking growth rates by combination of crack tip mechanics and crack tip oxidation kinetics", Corros. Sci., Vol. 52, pp. 769-779. https://doi.org/10.1016/j.corsci.2009.10.041
  7. Xu, P., Zhao, L.Y., Sridharan, K. and Allen, T.R., 2012, "Oxidation behavior of grain boundary engineered alloy 690 in supercritical water environment", J. Nucl. Mater., Vol. 422, pp. 143-151. https://doi.org/10.1016/j.jnucmat.2011.12.022
  8. Jeangros, Q., Hansen, T.W., Wagner, J.B., Dunin-Borkowski, R.E., H?bert, C., Van herle, J. and Hessler-Wyser, A., 2014, "Oxidation mechanism of nickel particles studied in an environmental transmission electron microscope", Acta Mater., Vol. 67, pp. 362-372. https://doi.org/10.1016/j.actamat.2013.12.035
  9. Kim, J., Kim, S.H., Choi, K.J., Bahn, C.B., Hwang, I.S. and Kim, J.H., 2014, "In-situ investigation of thermal aging effect on oxide formation in Ni-base alloy/low alloy steel dissimilar metal weld interfaces", Corros. Sci., Vol. 86, pp. 295-303. https://doi.org/10.1016/j.corsci.2014.06.006
  10. Choi, K.J., Yoo, S.C., Kim, T., Bahn, C.B. and Kim, J.H., 2015, "Effects of aging temperature on microstructural evolution at dissimilar metal weld interfaces", J. Nucl. Mater., Vol. 462, pp. 54-63. https://doi.org/10.1016/j.jnucmat.2015.03.044
  11. Yoo, S.C., Choi, K.J., Bahn, C.B., Kim, S.H., Kim, J.Y. and Kim, J.H., 2015, "Effects of thermal aging on the microstructure of Type-II boundaries in dissimilar metal weld joints", J. Nucl. Mater., Vol. 459, pp. 2-12.
  12. Zhu, M.-L., Wang, D.-Q. and Xuan, F.-Z., 2014, "Effect of long-term aging on microstructure and local behavior in the heat-affected zone of a Ni-Cr-Mo-V steel welded joint", Mater. Charact., Vol. 87, pp. 45-61. https://doi.org/10.1016/j.matchar.2013.10.026
  13. ASTM E407-7, 2007, "Standard practice for microetching metals and alloys", ASTM international
  14. ISO 6507-1, 1997, "Metallic materials - Vickers hardness test - Part 1 : Test method", International standard
  15. Yoo, S.C., Choi, K.J., Kim, T., Kim, S.H., Kim, J.Y. and Kim, J.H., 2016, "Microstructural evolution and stress-corrosion-cracking behavior of thermally aged Ni-Cr-Fe alloy", Corros. Sci., In press.
  16. Wang, L., Bei, H., Gao, Y.F., Lu, Z.P. and Nieh, T.G., 2011, "Effect of residual stresses on the hardness of bulk metallic glasses", Acta Mater., Vol. 59, pp. 2858-2864. https://doi.org/10.1016/j.actamat.2011.01.025