Transactions of the Korean Society of Mechanical Engineers A (대한기계학회논문집A)

The Korean Society of Mechanical Engineers (대한기계학회)
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Correlation Between Transient Regime and Steady-State Regime on Creep Crack Growth Behavior of Grade 91 Steel

Grade 91 강의 크리프 균열성장 거동에 대한 천이영역과 정상상태영역의 상관 관계

  • Park, Jae-Young (Dept. of Mechanical Engineering, Pukyong Nat'l Univ.) ;
  • Kim, Woo-Gon (Korea Atomic Energy Research Institute) ;
  • Ekaputra, I.M.W. (Dept. of Mechanical Engineering, Pukyong Nat'l Univ.) ;
  • Kim, Seon-Jin (Dept. of Mechanical Engineering, Pukyong Nat'l Univ.) ;
  • Kim, Eung-Seon (Korea Atomic Energy Research Institute)
  • 박재영 (부경대학교 기계설계공학과) ;
  • 김우곤 (한국원자력연구원 원자력소재개발부) ;
  • ;
  • 김선진 (부경대학교 기계설계공학과) ;
  • 김응선 (한국원자력연구원 수소생산원자로기술개발부)
  • Received : 2015.07.20
  • Accepted : 2015.09.04
  • Published : 2015.12.01
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Abstract

A correlation between the transient regime and steady state regime on the creep crack growth (CCG) for Grade 91 steel, which is used as the structural material for the Gen-IV reactor systems, was investigated. A series of CCG tests were performed using 1/2" CT specimens under a constant applied load and at a constant temperature of $600^{\circ}C$. The CCG rates for the transient and steady state regimes were obtained in terms of $C^*$ parameter. The transient CCG rate had a close correlation with the steady-state CCG rate, as the slope of the transient CCG data was very similar to that of the steady state data. The transient rate was slower by 5.6 times as compared to the steady state rate. It can be inferred that the steady state CCG rate, which is required for long-time tests, can be predicted from the transient CCG rate obtained from short-time tests.

제 4 세대 원자로의 고온 구조재료로 사되는 Grade 91 강의 크리프 균열성장 거동에 대한 천이영역과 정상상태영역에서의 상관 관계를 조사하였다. 이를 위해 $600^{\circ}C$의 동일한 온도 및 동일한 하중조건에서 1/2" CT 시편을 사하여 크리프 균열성장 시험 데이터를 얻었다. 크리프 균열성장 속도식은 $C^*$-파괴매개변수를 사하여 천이영역과 정상상태영역에서의 평가 식을 각각 도출하였다. $C^*$와 da/dt 의 관계에서 천이영역의 크리프 균열성장 속도는 시험 데이터의 산포가 크지만 정상상태영역의 크리프 균열성장 속도와 비슷한 기울기로서 상관성이 있었으며 천이영역 균열성장속도는 정상상태 균열성장속도에 비해 약 5.6 배 낮았다. 본 결과를 이하면 짧은 시간의 천이영역 균열성장속도로부터 장시간의 시험으로 얻을 수 있는 정상상태 균열성장속도를 예측할 수 있다.

Keywords

References

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