Cyclic plasticity and lifetime of the nickel-based Alloy C-263: Experiments, models and component simulation

Abstract

Abstract. The present work deals with the thermomechanical fatigue and low-cycle fatigue behavior of C-263 in two different material conditions. Microstructural characteristics and fracture modes are investigated with light and electron microscopy. The experimental results indicate that viscoplastic deformations depend on the heat treatment or rather on the current state of the microstructure. The measured data are used to adjust the parameters of a Chaboche type model and a fracture-mechanics based model for fatigue lifetime prediction. The Chaboche model is able to describe the essential phenomena of time and temperature dependent cyclic plasticity including the complex cyclic hardening during thermo-cyclic loading of both material conditions with a unique set of material parameters. This could be achieved by including an additional internal variable into the Chaboche model which accounts for changes in the precipitation microstructure during high temperature loading. Furthermore, the proposed lifetime model is well suited for a common fatigue life prediction of both investigated heats. The deformation and lifetime models are implemented into a user defined material routine. In this work, the material routine is applied for the lifetime prediction of a critical power plant component using the finite element method.

Procedures for handling computationally heavy cyclic load cases with application to a disc alloy material

“…the repeated starts and stops for a stationary gas turbine balancing the power grid or the many take-offs and landings for an aircraft engine operating midrange distances. Under these circumstances a component such as a turbine disc will experience thermomechanical fatigue [19][20][21], low-cycle fatigue [22][23][24], highcycle fatigue [25], creep [26], mean stress relaxation [27], creep-fatigue crack growth [28], dwell crack growth [29] etc., and thus, an appropriate constitutive model needs to be utilised to account for the behaviour of the material. Focusing attention on disc alloys, as a non-linear hardening behaviour is generally adopted, see e.g.…”