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

The Korean Society of Mechanical Engineers (대한기계학회)
권호 표지
DOI QR코드

DOI QR Code

Evaluation of Creep Fatigue Crack Growth Behavior of 9Cr Steel Employing Creep Reversal Parameter

크리프 역전 변수 도입에 의한 9Cr강의 크리프 피로 균열성장 거동의 평가

  • Published : 2002.07.01
Download PDF
⟨ Previous Next ⟩

Abstract

Creep-fatigue crack growth models have been proposed employing $(C_t)_{avg}$ as a crack tip parameter characterizing the time-dependent crack growth. The basic assumptions made in these previous models were ideal creep reversal conditions such as no creep reversal and complete creep reversal condition. Due to this assumption, the applicability of the models was limited since they did not consider partial creep reversal condition which is usually observed in many engineering metals at high temperature. In this paper the creep reversal parameter, Temperature;$C_R$, which was defined by Grover, is critically evaluated to quantity the extent of partial creep reversal at the crack tip. This approach does not rely on any simplifying assumptions regarding the extent of the amount of creep reversal during the unloading part of a trapezoidal fatigue cycles. It is shown that the $(C_t)_{avg}$ value calculated for 9Cr steel agrees well with the experimentally measured one. It is argued that the extent of improvement is not significant when the result is compared with that of the conventional model which has an assumption of full creep reversal behavior.

Keywords

References

  1. Riedel, H., 1987, 'Fracture at High Temperature,' Springer-Verlag
  2. Yoon, K. B., Saxena, A. and McDowell, D. L., 1992, 'Influence of Crack Tip Cyclic Plasticity on Creep-Fatigue Crack Growth,' ASTM STP 1131, pp. 367 - 392
  3. Yoon, K. B., Saxena, A. and Liaw, P. K., 1993, 'Characterization of Creep-Fatigue Crack Growth Behavior under Trapezoidal Waveshape using Ct-Parameter,' International Journal of Fracture Vol.59, pp. 95 - 114 https://doi.org/10.1007/BF00012385
  4. Adefris, N., 1993, 'Creep-Fatigue Crack Growth Behavior of 1Cr-1Mo-1/4V Rotor Steel,' Ph. D. Thesis, School of Materials Science and engineering, Georgia Institute of Technology, Atlanta, GA
  5. Yoon, K. B. and Lee, J. S., 2000, 'Evaluation of Ct-parameter for Weld Interface Crack Considering Material Plastic Behavior,' Transaction of the KSME, Vol. 24, No.3, pp. 676-684
  6. Yoon, K. B., Kim, K. W. and Baek, U. B., 1998, 'Modeling of Creep Crack Growth Behavior of Low-Alloy Steel Weld,' Transaction of the KSME, Vol. 22, No. 12, pp. 2153 - 2162
  7. Grover, P. S., 1996, 'Creep-Fatigue Crack Growth in Cr-Mo-V Base Material and Weldments,' Ph. D. Thesis, School of Materials Science and Engineering, Georgia Institute of Technology, Atlanta, GA
  8. Johnson. H. H., 1965, 'Calibrating the Electrical Potential Method for Studying Slow Crack Growth,' Material Research and Standard, Vol. 5, No.9, pp. 442-445
  9. Saxena, A., 1980, 'Electrical Potential Technique For Monitoring Subcritical Crack Growth at Elevated Temperature,' Eng. Fracture Mechanics, Vol. 13, No.4, pp. 741-750 https://doi.org/10.1016/0013-7944(80)90005-3
  10. Baek, U. B., Nahm, S. H., Suh, C. M. and Yoon, K. B., 1994, 'A Study on initial Transient Behavior in Creep-Fatigue Crack Growth,' Transaction of the KSME, Vol. 18, No.7, pp. 1722-1729
  11. Baek, U. B., Yoon, K. B., Lee, H. M. and Suh, C. M., 2000, 'Creep-Fatigue Crack Growth at CrMo Steel Weld Interface,' Transaction of the KSME A, Vol. 24, No. 12, pp. 3088-3095
  12. Baek, U. B., Yoon, K. B., Suh, C. M. and Lee, H. M., 2000, 'An Experimental Study on High Temperature Material Properties of Welded Joint,' Transaction of the KSME A, Vol. 24, No. 11, pp. 3096-3101
  13. Yoon, K. B., Baek, U. B. and Suh, C. M., 1997, 'Effects of Loading Rate on Creep Crack Growth During the Succeeding Load-Hold Period under Trapezoidal Fatigue Waveshapes,' Elevated Temperature Effects on Fatigue and Fracture, ASTM STP 1297, pp. 102-116
  14. Ma, Y. W., Baek, U. B. and Yoon, K. B., 2001, 'Introduction of Creep-Reversal Parameter for Improving Fatigue Crack Growth Life Assessment Model at High Temperature,' Proc. 2nd Conf. for Mat. & Fract. in 2001. KSME, pp. 265-271
  15. Baek, S. G., Song, G. W. and Hyun, J. S., 1998, 'Low Cycle Creep-Fatigue Life Prediction 1Cr-0.5Mo Pipe Steel with Hold Time Effects by Using the Plastic Strain Energy,' Transaction of the KSME A, Vol. 22, No. 12, pp. 2093-2099