Journal of Mechanical Science and Technology

The Korean Society of Mechanical Engineers (대한기계학회)
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Evaluation of Fracture Toughness Degradation of CrMoV Rotor Steels Based on Ultrasonic Nonlinearity Measurements

  • Hyunjo Jeong (Division of Mechanical Engineering, Wonkwang University) ;
  • Nahm, Seung-Hoon (Nondestrictive Measurement Group, Korea Research Institute of Standards and Science) ;
  • Jhang, Kyung-Young (School of Mechanical Engineering, Hanyang University) ;
  • Nam, Young-Hyun (Nondestructive Measurement Group, Korea Research Institute of Standards and Science)
  • Published : 2002.02.01
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Abstract

The objective of this paper is to develop a nondestructive method for estimating the fracture toughness (K$\_$IC/) of CrMoV steels used as the rotor material of steam turbines in power plants. To achieve this objective, a number of CrMoV steel samples were heat-treated, and the fracture appearance transition temperature (FATT) was determined as a function of aging time. Nonlinear ultrasonics was employed as the theoretical basis to explain the harmonic generation in a damaged material, and the nonlinearity parameter of the second harmonic wave was the experimental measure used to be correlated to the fracture toughness of the rotor steel. The nondestructive procedure for estimating the 7c consists of two steps. First, the correlations between the nonlinearity parameter and the FATT are sought. The FATT values are then used to estimate K$\_$IC/, using the K$\_$IC/ versus excess temperature (i.e., T-FATT) correlation that is available in the literature for CrMoV rotor steel.

Keywords

References

  1. Abdel-Latif, A.M., Corbett, J.M., Sidey, D. and Taplin,D.M.R., 1981, 'Effects of Microstructural Degradation of Creep Life Prediction of 2.25Cr-1Mo Steel,' Proc. of 5th Int. Conf.Fracture(ICF5), Vol. 4, pp. 1613-1620
  2. Foulds, J. and Viswanathan, R., 1994, 'Small Punch Testing for Determining the Material Toughness of Low Alloy Steel Component in Service,' Journal of Engineering Materials and Technology, Vol. 115, No. 4, pp. 457-464 https://doi.org/10.1115/1.2904313
  3. Frouin, J., Sathish, S., Matickas, T.E. and Na, J.K., 1999, 'Ultrasonic linear and nonlinear behavior of fatigued Ti-6A1-4V ,' Journal of Materials Research, Vol. 14, No. 4, pp. 1295-1298 https://doi.org/10.1557/JMR.1999.0176
  4. Ha, J.S. and Fleury, E., 1998, 'Small Punch Tests to Estimate the Mechanical Properites of Steels for Steam Power Plant: Ⅱ. Fracture Toughness,' International Journal of Pressure Vessels and Piping, Vol. 75, pp. 707-713 https://doi.org/10.1016/S0308-0161(98)00075-1
  5. Hikata, A., Chick, B.B. and Elbaum,C., 1965, 'Dislocation Contribution to the Second Harmonic Generation of Ultrasonic Waves,' Journal of Applied Physics, Vol. 36, No. 1, pp. 229-236 https://doi.org/10.1063/1.1713881
  6. Holzmann, N., Dlouhy, I., Vlach, B. and Krumpos, J., 1996, 'Degradation of Mechanical Properties of Cr-Mo-V and Cr-Mo-V-W Steam Turbine Rotors After Long-Term Operation at Elevated Temperatures. Part Ⅱ: Fracture Toughness, correlation of Fracture Toughness with Charpy V-Notch Results,' International Journal of Pressure Vessel & Piping, Vol. 68, pp. 113-120 https://doi.org/10.1016/0308-0161(95)00043-7
  7. Jhang, K.Y. and Kim,K.J., 1999, 'Evlauation of Material Degradation Using Nonlinear Acoustic Effect,' Ultrasonics, 37, pp. 39-44 https://doi.org/10.1016/S0041-624X(98)00045-6
  8. Nahm, S.H., Kim, A. and Yu, K.M., 1998, 'Nondestructive Evaluation of Toughness Degradation of 1Cr-1Mo-0.25V Steel Using Electrical Resistivity,' proceedings of KSME A, Vol. 22, No. 5, pp. 814-820
  9. Nishiyama, Y., Fukaya, K., Suzuki, M., Eto, M. and Shoji, T., 1994, 'Electrochemical Monitoring of Aging Embrittlement of 2 1/4Cr-1Mo Steel for Gas-Cooled Reactor Pressure Boundary Components,' Theoretical and Applied Fracture Mechanics, 21, 1, pp. 51-57 https://doi.org/10.1016/0167-8442(94)90008-6
  10. Rothenfusser, M., Mayr, M. and Baumann, J., 2000, 'Acoustic Nonlinearities in Adhesive Joints,' Ultrasonics, 38, pp.322-326 https://doi.org/10.1016/S0041-624X(99)00083-9
  11. Shekhter, A., Croker, A.B.L., Hellier, A.K., Moss, C.J. and Ringer, S.P., 2000, 'Towards the Correlation of Fracture Toughness in an Ex-Service Power Generating Rotor,' International Journal of Pressure Vessels and Piping, Vol. 77, pp. 113-116 https://doi.org/10.1016/S0308-0161(99)00091-5
  12. TenCate, J.A. and Van Den Abble,K.E., 1996, 'Laboratory Study of Linear and Nonlinear Elastic Pulse Propagation in Sandstone,' Journal of the Acoustical society of America, Vol. 100, No. 3, pp. 1383-1389 https://doi.org/10.1121/1.415985
  13. Viswanathan, R. and Bruemmer, S.M., 1985, 'In-Service Degradation of Toughness of Steam Turbine Rotors,' Journal of Engineering Materials and Technology, Vol. 107, pp. 317-324
  14. Viswanathan, R. and Gehl, S., 1991, 'A Method for Estimation of the Fracture Toughness of CrMoV Rotor Steels Based on Composition,' Journal of Engineering Materials and Technology, Vol. 113, No. 2, pp. 263-270 https://doi.org/10.1115/1.2903401
  15. Yost, W.T., Cantrell, J.H., Na, J.K., 2001, 'Nonlinear Ultrasonic Pulsed Measurements and Applications to Metal Processing and Fatigue,' Review of Progress in Quantitative Nondestructive Evaluation, Vol. 20, eds. D.O.Thompson, D.E.Chimenti, American Institute of Physics, pp. 1268-1275