Creep rupture properties of a NiCrW superalloy in air environment

The creep rupture properties in air environment were studied at 900, 1000 and 1050°C for bar, plate and seamless tube materials of a NiCrW superalloy developed for use at service temperatures around 1000°C. The long-term creep rupture strength is estimated by applying the time-temperature parameter method to the creep rupture data. Data of anomalous behaviour due to oxidation strengthening, which is observed in creep curves with rupture times above ∼ 10 000 h at 1000°C, are corrected for the application of the time-temperature parameter method. The Larson-Miller parameter method is better than the Orr-Sherby-Dorn parameter method in respect of curve fitting to the present creep rupture data. The creep rupture strength of the bar material with grain sizes above ASTM No. 2 and of the plate material is above 9.8 MPa for a 1 × 10 5 h life at 1000°C, which is the final target of this program. The creep rupture strength increases with increasing grain size and heat treatment temperature.