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Evaluation of Degradation Behavior of the Long-Term Serviced Boiler Header

장기 사용 보일러 헤더의 열화거동 평가에 관한 연구

  • Published : 2000.07.01

Abstract

The degradation of a boiler header constructed by a material, 1Cr-0.5Mo steel in a fossil power plant is observed when the header is exposed for a long period to the high temperature and pressure. The present investigations are for evaluating the effect of the degradation on the material, such as its strength changes. Reheat-treated metal is used to compare the mechanical properties of the degraded and that of reheat-treated materials. Through the investigation, following results are obtained 1) the area ratio of ferrite in the reheat-treated material is larger than that of the degraded material, 2) the hardness and tensile strength of the degraded material are lower than that of the reheat-treated material, 3) the ductile-brittle transition temperature(DBTT) increased toward high temperature region, 4) the fatigue crack growth rate(FCGR) of the degraded material is higher than that of the reheat-treated material in the region of low ΔK value while FCGR of the both materials are similar in high ΔK region.

Keywords

References

  1. Watanabe, Y., and Shoji, T., 1991, 'The Evaluation of in-service Materials Degradation of Low Alloy Steels by The Electrochemical Method,' Met. Trans., Vol. 22A, pp. 2097-2106 https://doi.org/10.1007/BF02669877
  2. Abdel-Latif, A. M., Corbett, J. M., Sidey, D., Taplin, D. M. R., 1981, 'Effect of Microstructural Degradation in Creep Life Prediction of 2.25Cr-1Mo Steel,' Proceeding of the 5th ICF, Cannes, France, Vol. 4, pp. 1613-1620
  3. Burghad, H. C., McCann, D. R., 1984, 'Fractographic Analysis of a Steam Turbine Disk Failure,' ASTM STP 827, pp. 106-114
  4. Katsumata, M., Takada, H., et al., 1981, 'Temper Embrittlement in Pressure Vessel Steel,' JHPI, Vol. 12, No. 3, pp. 8-14
  5. 材上賀國, 1983, '壓力容器用Cr-Mo鋼の燒屯胞性に關する硏究,' 大阪大學工學部 博士學位論文
  6. Biss, V. A., and Wada, T., 1985, 'Microstructural Changes in 1Cr-0.5Mo Steel after 20 Years of Services,' Met. Trans., Vol. 16A, pp. 109-114 https://doi.org/10.1007/BF02656718
  7. Nishizaka, Y., Hara, Y., Hori, A., Tsukahara, H.,Miyano, K., Wada, T., Cox, T. B., 1985, 'Changes in Microstructure and Mechanical Properties of Cr-Mo Reactor Vessel Steels During Long-Term Services,' Journal of Pressure Vessel Technology, Vol. 107, pp. 285-294
  8. JIS G 0552 (ISO 643), 1998, 'Methods of Ferrite Grain Determination Test for Steel,' pp. 1-23 (in japanese)
  9. 권재도, 1992, '장기사용 Cr-Mo강 열화재에 파괴인성평가와 수명예측,' 대한기계학회논문집, 제16권, 18호, pp. 1421-1426
  10. 권재도, 진영준, 류승우, 장순식, 1993, '다단계 모의 열화재의 재료강도 평가와 수명예측,' 대한기계학회논문집, 제17권, 제9호, pp. 2271-2279