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Vol.43, No.6, 455 ~ 461, 2005
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| Title |
| Evaluation of the Service Time under the Moisture Erosion of the Flame-Hardened and Stellite-Brazed Last Stage Rotor Blades in Low Pressure Nuclear Steam Turbine |
| 이민구 Min Ku Lee , 김경호 Kyeong Ho Kim , 김광호 Gwang Ho Kim , 김홍회 Whung Whoe Kim |
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| Abstract |
| This paper presents the long-term monitoring results from the water droplet erosion (or moisture erosion) and the analysis of the service life of the last stage rotor blades, particularly the flame-hardened and Stellite-brazed blades, of LP (low pressure) section in Gori, Wolsung, Youngkwang, and Uljin nuclear power plants. The flow of wet steam caused the considerable erosion damage on the leading edge of the last stage rotor blades. Characterization of the erosion process with the operation time has shown that there were three characteristic modes including the first region without showing evident material loss, the second region with a drastic material loss with maximum erosion rate, and the third region with relatively slow erosion rate. Such erosion behavior indicated that the erosive damage on the material was developed by the fatigue fracture induced by repeated impact loads. Based on the simplilled model and calculation, the service life of the last stage rotor blade has been estimated at about 223000 hrs for the flame-hardened blade and 185000 hrs for the Stellite-brazed blade. |
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| Key Words |
| Steam turbine, Rotor blades, 12Cr steel, Stellite, Flame hardening, Moisture erosion, Service Life |
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