Creep Life Prediction for Hastelloy XR Using the Omega Method

Abstract

This paper applies the Omega method to creep life prediction for Hastelloy XR at temperatures ranging from 850 to 950^oC in an air environment. The creep data were obtained from literature. Three life prediction scenarios were studied including constant stress, constant load, and continuous monitoring where creep data is simulated for sequential acquisition. The constant stress creep data at each temperature were used to determine the Omega model parameters, and empirical equations for each parameter were developed. The predicted creep lives under constant stress were within a factor of 2 in almost all cases. For a life prediction under constant load, the actual applied stress was estimated and used in the creep constitutive equation as well as for calculating the model parameters. The predicted creep lives were also to be within a factor of 2 in almost all cases. The Omega model was found to be applicable to a continuous creep data acquisition scenario as well. An appropriate scheme for continuous monitoring scenario was suggested, and statistical analysis by the Monte Carlo simulation was demonstrated.