Abstract
X-ray diffraction (XRD) studies were carried out on 2·25Cr–1Mo steel boiler tubes from a thermal power station with an objective of developing a faster method of health assessment of this steel at elevated temperatures on a routine basis. Carbide phase transformations in virgin and service exposed boiler tubes (up to ∼100 000 h) were determined for plate specimens using high power X-rays. Iron and chromium rich carbides were detected by XRD at various stages of transformation towards final equilibrium. Compositional variations of equilibrium precipitate M23 C6 with service life or overheating in the specimens studied were monitored by a shift in the lattice parameter. The XRD results were validated by optical and electron microscopy, hardness measurements, and particle size measurements.
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