Development of a new lifetime prediction method for gas turbine core parts by digital image analysis of precipitates morphology

석출물 형상의 디지털 이미지 분석에 의한 가스터빈 핵심부품의 새로운 수명평가기술 개발

  • 장문수 (서경대학교 소프트웨어학과) ;
  • 안성욱 (캐스텍(주) 주조기술연구소)
  • Received : 2007.11.21
  • Accepted : 2008.04.03
  • Published : 2008.04.25

Abstract

To describe the lifetime prediction of gas turbine core parts serviced in some ten thousands rpms at over $1,000^{\circ}C$, the Larson-Miller Creep Curves, which are formed by creep rupture tests as the destructive experiment with parameters of stress and temperature, are used often, but not exact and reliable with errors of over some tens. On the other hand, this study shows a non-destructive method with increased accuracy and reliability. The SEM and TEM specimens were extracted by replica after polishing the local airfoil and root surfaces of the first stage scraped blade (bucket), serviced for 18,000 hours at $1,280^{\circ}C$ in Gas Turbines of Boryong. The observed TEM and SEM precipitates were digitalized for calculation of the average size. Here we could find the precipitate size grown from $0.45{\mu}m$ to $0.6{\mu}m$ during service and the grown precipitates to be still sound. From these results we could conclude that the scraped balde can be used for ten thous and hours additionally and for twenty thousand hours by additional heat treatments on the scraped blade.

References

  1. G. K. Bouse and S. W. K. Shaw, 'Development of Superalloys', Materials Science and Technology 3, 682-700 (1987) https://doi.org/10.1179/026708387790329847
  2. R. F. Decker and C. T. Sims, 'The Metallurgy of Nickel- Base Alloys',vol. 2, The Superalloys, Ed. C. T. Sims and W. C. Hagel, Ed. John Wiley & Sons, Inc., 33-77, 1972
  3. L. M. Brown and R. K. Ham, Strengthening methods in crystals. Ed. A. Kelly and R. B. Nicholson, Appl. Sci. Publ., London, 1971
  4. W. Huethner and B. Reppich, Zeitschrift fuer Metallkunde, 69, 628-634(1978)
  5. Willi Schneider, Hochtemperaturkriechverhalten and Mikrostruktur der Einkristallinen Nickelbasis-Superlegierung CMSX 4 bei Temperaturen von 800 bis 1,100, Dissertation, Uni. Erlangen-Nuernberg, 1993
  6. G. L. Erickson, Invited Paper Presented at the Processing and Design Issues in High Temperature Materials, Davos, Switzerland, 19, May 1996
  7. Horst Biermann, Berthold von Grossmann, Thomas Schneider, Hua Feng and Hael Mughrabi, Superalloys, Ed.R. D. Kissinger et al., TMS 201-210, 1996
  8. F. R. Larson and J. Miller, Trans. ASME, 74, 765-770(1996)