REMAINING LIFE ASSESSMENT OF THERMAL POWER-PLANT COMPONENTS BY IN-SITU METALLOGRAPHY

High temperature components of thermal power plants and process boiler s at the expiry of designed life are evaluated for creep damage by imp roved in-situ metallographic sample preparation and evaluation. Extens ive field metallography of numerous power plants and process boilers h as shown creep damages of different levels and they reflect that high quality sample preparation and evaluation are essential in order to es timate the damage state of the material. Carbide spheroidization, cree p pores of different shapes, oriented creep pores and creep cracks wer e observed in the gold sputtered field replicas of low alloy Cr-Mo ste el steam pipes after service. Typical light optical microscopy of fiel d replicas and the results are discussed.