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Creep Design of Type 316LN Stainless Steel by K-R Damage Theory

K-R 손상이론에 의한 316LN 스테인리스강의 크리프 설계

  • Kim, U-Gon (Nuclear Fuel Technology Center, Korea Atomic Energy Research Institute) ;
  • Kim, Dae-Hwan (Nuclear Fuel Technology Center, Korea Atomic Energy Research Institute) ;
  • Ryu, U-Seok
  • 김우곤 (한국원자력연구소 원자력재료기술개발팀) ;
  • 김대환 (한국원자력연구소 원자력재료기술개발팀) ;
  • 류우석
  • Published : 2001.02.01

Abstract

Kachanov-Rabotnov(K-R) creep damage theory was reviewed, and applied to design a creep curve for type 316LN stainless steel. Seven coefficients used in the theory, i.e., A, B, k, m, λ, r, and q were determined, and their physical meanings were analyzed clearly. In order to quantify a damage parameter ($\omega$), cavity amount was measured in the crept specimen taken from interrupted creep test with time variation, and then the amount was reflected into K-R damage equations. Coefficient λ, which is regarded as a creep tolerance feature of a material, increased with creep strain. Mater curve with λ=2.8 was well coincided with an experimental one to the full lifetime. The relationship between damage parameter and life fraction was matched with the theory at exponent ${\gamma}$=24 value. It is concluded that K-R damage equation was reliable as the modelling equation for type 316LN stainless steel. Coefficient data obtained from type 316LN stainless steel can be utilized for life prediction of operating material.

Keywords

Damage Parameter;316LN Stainless Steel;Kachanov-Rabotnov Creep Damage;Monkman-Grant Strain;Creep Rate;Creep Cavity

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