Thermomechanical fatigue behaviour of nickel base superalloy IN738LC Part 1 – Comparison of two unified constitutive models for description of mechanical behaviour

Abstract

The capabilities of two unified constitutive models to predict the mechanical behaviour of nickel base superalloy IN738LC under uniaxial loading conditions have been investigated over the temperature range 450–850°C. The material parameters of each model have been identified from an experimental investigation and complemented by available data from the literature. Mechanical responses from isothermal tests performed at 450 and 850°C (such as creep, monotonic, and fully reversed isothermal cyclic tests) were used for the identification of model parameters, and model capabilities were examined by comparison with in phase and out of phase thermomechanical fatigue and stress relaxation tests. Both models were found to capture all features of the material responses under uniaxial loading, although with varying degrees of accuracy.