Modelling of the impact of the thermo-mechanical load collective on the rim zone microstructure when cutting TiAl6V4

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The rotating components of a jet engine are highly safety-critical parts. In the worst case, a technical defect in those components can cause loss of human life. The functionality and operational behavior of these components is strongly influenced by the properties of the component’s rim zone, which in turn is defined by the final manufacturing process. Therefore, the machining process, as the final manufacturing process in the production chain, has a considerable influence on the component properties. An important parameter for the characterization of the surface rim zone is the grain size. Thereby, the thermo-mechanical loads that are induced by the manufacturing process affect the grain size. The underlying causes and mechanisms are unknown, which is why existing models to describe the alteration of the grain size have only insufficient predictive accuracy. Within the scope of this research project a model-based description of machining induced grain size alteration for the titanium alloy Ti-6Al-4V will be developed. For this purpose, a thermodynamic approach will be used. The description of the model will be derived via complementary investigation methods. On the one hand, empirical machining investigations and their metallographic evaluations and on the other hand, chip formation simulations are utilized. The influence of the machining process on the material’s grain size, measured on the basis of empirical tests, are related to the local material loads calculated from chip formation simulations. In addition, analytical models will be used, which allow the consideration of material-specific properties. With the model of the grain size alteration and the integration of the model into a FEM-chip formation simulation, the need for a continuous description of the effect of the cutting process on the grain size in the sense of a simulation-supported process design will be fulfilled.