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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

Abstract

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.

Keywords

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

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