High thermal conductivity, low coefficient of thermal expansion makes P92 a candidate material for Ultra Super Critical (USC) power plant piping. Microstructural features viz., high dislocation density, lath martensitic microstructure, fine precipitates of M23C6 and MX (X=C, N) contribute towards the high rupture strength. However, most components are typically subjected to multiaxial stress conditions; either metallurgical (weldments), or mechanical (change in the dimension). The present work involves stress rupture testing of circumferential 60° V- notch specimens in the range of 300 – 375 MPa at 650 °C. Notch strengthening effect was observed; with rupture times ranging from 200 – 1300 h. Scanning electron microscopy (SEM) fractography revealed mixed mode of fracture with brittle fracture observed at notch root, while ductile fracture was seen at the centre of the specimen.
