Thermo-mechanical processes of turbine disks have been progressively improved to meet microstructural requirements tailored for advanced, sustainable high temperature performances. However, the chemistry of typical Ni-base turbine disk alloys is very complex, and yields a variety of phases and microstructural anomalies under different thermo-mechanical heat treatments. These microstructural heterogeneities and anomalies often limit thermo-mechanical behaviors of turbine disks. The proposed Phase I program will focus on the development of multi-physics based computational tools and approaches for the prediction of HT-processing dependent microstructures, the characterization of their statistical features/anomalies and the corresponding mechanical responses, and the identification of the critical microstructural feature that may limit the performance life. A conventional Ni-base polycrystalline superalloy IN718 was chosen as a target material for the proposed work because of its most common usage for the turbine disk application and the large amount of data available from various resources. Due to the microstructural complexity of IN718, the property prediction requires rigorous numerical approaches to account for microstructural heterogeneities. The successful completion of Phase I efforts will bring microstructure-sensitive computational tools and approaches for the evaluation of differently processed IN718 disk alloys.
Benefit: The proposed Phase I program intends to develop modeling tools and approaches for the prediction of the spatial grain distribution, precipitate fractions and yield stresses, and the estimation of the criticality of the simulated microstructure as a life-limiting precursor for the turbine disk alloy IN718 processed by different heat treatment processing conditions. The successful completion of Phase I efforts will bring microstructure-sensitive computational tools and approaches for the evaluation of differently processed IN718 disk alloys. The Phase II program will involve the calibration and experimental validation for some of the Phase I modeling tools, and the homogenization of Phase I mesoscale simulation results for the implementation at the continuum scale for the prediction of the component-level properties. Upon successful completion of Phases I and II programs new computational prediction tools will be ready for the IN718 turbine disk application. We will work closely with our OEM partner to transition the prediction tool and apply it to a component. At the end of the Phases I & II programs, we anticipate licensing the modeling tool to our OEM partner and continue to refine the product in the years following.
Keywords: ALA (as-large-as) grain, ALA (as-large-as) grain, Life-limiting, turbine disk, Ni-base superalloy, microstructure, Modeling, Residual Stress, IN718
