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A Correlation of Striation Spacing and DHC Velocity in Zr-2.5Nb Tubes

Zr-2.5Nb 압력관에서 Striation Spacing과 DHCV의 관계

  • 최승준 (한국원자력연구소, 지르코늄팀) ;
  • 안상복 (한국원자력연구소, 지르코늄팀) ;
  • 박순삼 (한국원자력연구소, 지르코늄팀) ;
  • 김영석 (한국원자력연구소, 지르코늄팀)
  • Published : 2004.08.01

Abstract

The objective of this study is to elucidate what governs delayed hydride cracking (DHC) in Zr-2.5Nb tubes by correlating the striation spacings with DHCV(DHC Velocity). To this end, DHC tests were conducted on the compact tension specimens taken from the Zr-2.5Nb tubes at different temperatures ranging from 100 to $300^{\circ}C$ with a 3 to 6 data set at each test conditions. The compact tension specimens were electrolytically charged with 27 to 87 ppm H before DHC tests. After DHC tests, the striation spacings and DHCV were determined with the increasing the test temperature and yield strength. The striation spacing and DHCV increased as a function of yield $strength^2$ and the temperature. Since the plastic zone size ahead of the crack tip can be represented by ${\sim}(K_{IH}/{\sigma}_{Y})^2$, we conclude that the striation spacing is governed by the plastic zone size which in turn determines a gradient of hydrogen concentration at the crack tip. The relationship between the plastic zone size and the striation spacing was validated through a complimentary experiment using double cantilever beam specimens. Two main factors to govern DHCV of Zr-2.5Nb tubes are concluded to be hydrogen diffusion and a hydrogen concentration gradient at the crack tip that are controlled by temperature and yield strength, respectively. The activation energy of DHCV in the Zr-2.5Nb tubes is discussed on the basis of temperature dependency of hydrogen diffusion and the striation spacing.

Keywords

DHC;Delayed Hydride Cracking;Striation Spacing;Zr-2.5Nb;Pressure Tubes

References

  1. Parfenov, B. G., Gerasimov, V. V. and Venceliktova, G. I., 1984, 'Corrosion of Zirconium and Zirconium Alloys, translated from Russian, Israel Program for Scientific Translations
  2. Cox, B., 1984, 'Mechanism of Hydrogen Absorption by Zirconium alloys,' AECL-8702
  3. PuIs, M. P., 1975, 'Hydrogen-induced Delayed Cracking: 1. Strain Energy Effects on Hydrogen Solubility,' AECL-6302
  4. Oh, D. J., Ahn, S. B., Park, S. S., Ahn, C. Y. and Kim Y. S., 2000, 'The study of brittleness of fracture toughness of Zr-.2.5Nb tube by hydride,' KSME 2000, Autumn Regular Conference A, pp. 93-98
  5. Oh, J. Y., Kim, I. S. and Kim, Y. S., J. 1999, Kor. lnst. Met. & Mater. 37, 680
  6. Dutton, R., Nuttal, K., Puls, M. P. and Simpson, L. A., 1977, Metall. Trans. 8A, 1553 https://doi.org/10.1007/BF02644858
  7. Shek, G. K., Jovanovic, M. T., Seahra, H., Ma, Li, Y. D. and Eadie, R. L., 1996, J. Nucl. Mater., 231, 221 https://doi.org/10.1016/0022-3115(96)00370-4
  8. Pugh, E. N., 1985, Corrosion, 41, 517 https://doi.org/10.5006/1.3583022
  9. Lynch, S. P., 1989, Metallography, 23, 147 https://doi.org/10.1016/0026-0800(89)90016-5
  10. Y.S. Kim, Y. Perlovich, M. Isaenkova, S.S. Kim and Y.M. Cheong, 'Precipitation of Reoriented Hydrides and Textural Change of a-Zirconium Grains during Delayed Hydride Cracking of Zr2.5%Nb Pressure Tube, J. Nucl. Mater., 297, 292 (2001) https://doi.org/10.1016/S0022-3115(01)00628-6
  11. Kim, Y. S. et aI., 1999, KAERl Report, 'Procedure document of Zr-2.5Nb tube test', KAERI/TR-1329/99, Korea Atomic Energy Research Institute
  12. Oh, J. Y., Kim, I. S. and Kim, Y. S., 2000, J. Nucl. Sci. & Tech., 37, 595 https://doi.org/10.3327/jnst.37.595
  13. Shek, G. K. and Graham, D. B., 1989, 'Zirconium in the Nuclear Industry: Eighth International Symposium', ASTM STP 1023, 89
  14. Kim, Y.S. et al., 2003, presented at the CNS (Canadian Nuclear Society) 2003 Annual Conference Meeting, 2003. June 8
  15. Sawatzky, A., Ladoux, G. A., Tough, R. L. and Cann, C. D., 1982, in Proc. Miami Int. Symp. on Metal-Hydrogen Systems (Oxford; Pergamon Press), 109
  16. Skinner, B. C. and Dutton, R. 1990, Hydrogen Effects on Material Behavior, ed. N.R. Moody and A. W. Thompson, 93