A Study on Fracture Toughness with Thermal Aging in CF8M/SA508 Welds

CF8M과 SA508 용접재의 열화에 따른 파괴인성에 관한 연구

  • 우승완 (영남대학교 기계공학부) ;
  • 최영환 (한국원자력안전기술원) ;
  • 권재도 (영남대학교 기계공학부)
  • Published : 2006.10.01


In a primary reactor cooling system(RCS), a dissimilar weld zone exists between cast stainless steel(CF8M) in a pipe and low-alloy steel(SA508 cl.3) in a nozzle. Thermal aging is observed in CF8M as the RCS is exposed for a long period of time to a reactor operating temperature between 290 and $330^{\circ}C$, while no effect is observed in SA508 cl.3. The specimens are prepared by an artificially accelerated aging technique maintained for 300, 1800 and 3600 hrs at $430^{\circ}C$, respectively. The specimens for elastic-plastic fracture toughness tests are according to the process in the thermal notch is created in the heat affected zone(HAZ) of CF8M and deposited zone. From the experiments, the $J_{IC}$ value notched in HAZ of CF8M presented a rapid decrease up to 300 hours at $430^{\circ}C$ and slowly decreased according to the process in the thermal aging time. Also, the $J_{IC}$ value presented a lower value than that of the CF8M base metal. And, the $J_{IC}$ of the deposited zone presented the lowest value of all other cases.


Cast Stainless Steel;Low Alloy Steel;Dissimilar Weld;Thermal Aging;Fracture Toughness


  1. Robert, G. K and Andre, G. R, 1985, 'A Component Wear-out Analysis on Control Rod Drive Mechanisms,' Westinghouse, Pittsburgh
  2. Ware, A. G., 1982, ASTM STP 756, pp. 165-189
  3. Trautwein, A. and Gysel, W., 1982, 'Stainless Steel Casting,' ASTM STP 756, pp. 165-189
  4. Atkison, J. D. and Yu, J., 1997, Fatigue Fract Eng. Mater. Struct., 20, p. 1
  5. Kwon, J. D., Woo, S. W. and Choi, Y. H., 2004, KSME Int. J., Vol. 28, No. 12, pp. 1968-1973
  6. Byrnes, M. L. G., Grujicic, M. and Owen, W. S., 1987, Acta Metal. 35(1853)
  7. Kwon, J. D., Park, J. C., Lee, Y. S., Lee, W. H. and Park, Y. w., 2000, Nud. Eng. Des. 198, pp. 227-240
  8. Etchants, Metallography, Appendix- I, pp. 632-645
  9. ASTM E 813-87, 1989, 'Standard Test Method for $J_{IC}$, a Measure of Fracture Toughness'
  10. Kwon, J. D., Woo, S. W. and Choi, Y. H., 2004, Key Engineering Materials, Switzerland, Vols. 261-263, Part.1, pp. 1689-1694
  11. ASTM E1152-87, 1989, 'Standard Test Method for Detennining J-R Curves.'
  12. ASTM E399-90, 1992, 'Standard Test Method for Plain-Strain Fracture Toughness of Metallic Materials'
  13. Clarke, G. A., Andrews, W. R., Paris, P. C. and Schmidt, D. W., 1976, ASTM STP 590
  14. Kwon, J. D., Choi, S. J., Park, J. C. and Ihn, J. H., 2002, KSME Int. J, Vol. 16, No.7, pp. 902-910