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KMID : 0385520080210020148
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Analytical Science & Technology
2008 Volume.21 No. 2 p.148 ~ p.157
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Development of a new lifetime prediction method for gas turbine core parts by digital image analysis of precipitates morphology
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Chang Moon-Soo
An Seong-Uk
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Abstract
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To describe the lifetime prediction of gas turbine core parts serviced in some ten thousands rpms at over 1,000℃, 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℃ 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 μm to 0.6 ㎛ 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.
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KEYWORD
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lifetime, CMSX 4, single crystalblade(bucket), r’precipitate, r’ rafting, creep
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