Korean Journal of Metals and Materials (대한금속재료학회지)

The Korean Institute of Metals and Materials (대한금속재료학회)
권호 표지

Long-term Creep Strain-Time Curve Modeling of Alloy 617 for a VHTR Intermediate Heat Exchanger

초고온가스로 중간 열교환기용 Alloy 617의 장시간 크리프 변형률-시간 곡선 모델링

  • Kim, Woo-Gon (Nuclear Materials Research Division, Korea Atomic Energy Research Institute) ;
  • Yin, Song-Nam (Nuclear Materials Research Division, Korea Atomic Energy Research Institute) ;
  • Kim, Yong-Wan (Nuclear Materials Research Division, Korea Atomic Energy Research Institute)
  • 김우곤 (한국원자력연구원 원자력재료연구부) ;
  • 윤송남 (한국원자력연구원 원자력재료연구부) ;
  • 김용완 (한국원자력연구원 원자력재료연구부)
  • Received : 2009.03.18
  • Published : 2009.10.25
⟨ Previous Next ⟩

Abstract

The Kachanov-Rabotnov (K-R) creep model was proposed to accurately model the long-term creep curves above $10^5$ hours of Alloy 617. To this end, a series of creep data was obtained from creep tests conducted under different stress levels at $950^{\circ}C$. Using these data, the creep constants used in the K-R model and the modified K-R model were determined by a nonlinear least square fitting (NLSF) method, respectively. The K-R model yielded poor correspondence with the experimental curves, but the modified K-R model provided good agreement with the curves. Log-log plots of ${\varepsilon}^{\ast}$-stress and ${\varepsilon}^{\ast}$-time to rupture showed good linear relationships. Constants in the modified K-R model were obtained as ${\lambda}$=2.78, and $k=1.24$, and they showed behavior close to stress independency. Using these constants, long-term creep curves above $10^5$ hours obtained from short-term creep data can be modeled by implementing the modified K-R model.

Keywords

Acknowledgement

Supported by : 교육과학기술부

References

  1. W. G. Kim, D. W. Kim, W. S. Ryu, C. H. Han, J. H. Yoon, and J. H. Chang, Mechanical Properties and Its Comparison of Superalloys for High Temperature Gas Cooled Reactor, KAERI/AR-723/2005, p.1-39 (2005)
  2. W. G. Kim, S. N. Yin, Y. W. Kim, and J. H. Chang, Engineering Fracture Mechanics. 75, 4985 (2008) https://doi.org/10.1016/j.engfracmech.2008.06.017
  3. W. G. Kim, S. H. Kim, and W. S. Ryu, KSME Int. Journal. 16, 1420 (2002)
  4. R. K. Penny and D. L. Marriott, Design for Creep, 2nd ed., p.24-26, Chapman & Hall, London (1995)
  5. R. K. Penny, J. Metals and Materials. 8, 278 (1974)
  6. F. Garofalo, Fundamentals of Creep and Creep Rupture in Metals, p.10-27, Macmillan Co., New York (1966)
  7. R. Viswanathan, Damage Mechanisms and Life Assessment of High-Temperature Components, p.59-69, ASM International, Ohio (1989)
  8. L. D. Blackburn, Isochronous Stress Strain Curves for Austenitic Steels, p.14-48, ASME, New York (1972)
  9. R. W. Evans, J. D. Parker, and B. Wilshire, Int. J. of Pressure Vessels and Piping. 50, 147 (1992) https://doi.org/10.1016/0308-0161(92)90035-E
  10. K. Maruyama, C. Harada, and H. Oikawa, J. Soc. Mater. Sci. of Japan. 34, 1289 (1985) https://doi.org/10.2472/jsms.34.1289
  11. K. Natesan, A. Purohit, and S. W. Tam, Materials Behavior in HTGR Environments, NUREG/CR-6824, ANL-02/37, p.41-46 (2003)
  12. W. G. Kim, S. H. Kim, and W. S. Ryu, KSME Int. Journal. 15, 1463 (2001)
  13. H. J. Penkalla, H. H. Over, and F. Schubert, Nuclear Technology 66, 685 (1984) https://doi.org/10.13182/NT84-A33490
  14. W. G. Kim, S. N. Yin, W. S. Ryu, and C. B. Lee, J. Kor. Inst. Met. & Mater. 46, 118 (2008)
  15. W. G. Kim, S. N. Yiu, S. H. Kim, W. S. Ryu, C. B. Lee, and S. J. Kim, Met. Mater. Int., 15, 559 (2009) https://doi.org/10.1007/s12540-009-0559-9