A Review of Constitutive Models and Thermal Properties for Nickel-Based Superalloys Across Machining-Specific Regimes

Abstract

Nickel-based superalloys (Ni-alloys) are widely used in flight critical aeroengine components because of their excellent material properties at high temperatures such as yield strength, ductility, and creep resistance. However, these desirable high-temperature properties also make Ni-alloys very difficult to machine. This paper provides an overview and benchmarking of various constitutive models to provide the process modeling community with an objective comparison between various calibrated material models to increase the accuracy of process model predictions for machining of Ni-alloys. Various studies involving the Johnson–Cook model and the calibration of its constants in finite element simulations are discussed. It was found that significant discrepancies exist between researchers’ approaches to calibrating constitutive models. To this end, various “physics-based” models are discussed as an alternative to widely used “phenomenological” models like the Johnson–Cook model, supplemented by a discussion on the more precise inverse method for constitutive model calibration. This paper also provides a comprehensive overview of pedigreed physical material properties for a range of Ni-alloys—the variation of thermal properties and thermally induced stresses over machining temperature regimes are modeled for a variety of Ni-alloys. The chemical compositions and applications for a range of relevant Ni-alloys are also explored. Overall, this paper identifies the need for more comprehensive analysis and process-specific (e.g., in-situ) characterization of thermomechanical properties for difficult-to-machine Ni-alloys to improve machining performance and aeroengine component quality.