3D Tomography-Assisted Mechanistic Fatigue Modeling and Life Prediction for Dual Microstructure Heat Treated Aeroturbine Disks

To meet the increasing performance requirements of modern aeroturbine engines, a significant opportunity exists with the Dual Microstructure Heat Treatment (DMHT) technology for nickel-based aeroturbine disks. However, use of DMHT results in gradient microstructures and a major hurdle in perfecting this technology is a lack of mechanistic mechanical property modeling in the gradient region. QuesTek proposes to demonstrate the feasibility of a novel 3D tomography-assisted fatigue life property model on a RR1000 disk alloy, by combining capabilities developed in DARPA AIM and ONR/DARPA D3D initiatives, and a NASA DMHT precipitation microstructure modeling program. QuesTek will work with Rolls-Royce to identify the service conditions of a gas turbine engine disk component; incorporate 3D tomographic technology to identify the inclusion microstructure that represents the lowest fatigue life distribution; leverage available transient gamma-prime microstructure and mechanical property models and data from the ongoing Rolls-Royce and NASA programs, and collaborate with Professor David McDowell of GIT to demonstrate a mechanistic fatigue lifing model within the gradient region. This approach will be further extended to include a diffusional microtwinning-based creep-fatigue model during the service conditions in the Phase II to allow for a full range probabilistic lifing model for DMHT disk components. BENEFIT: The proposed program will develop a key ability needed for complete fatigue and life prediction of gradient microstructure aeroturbine disks. The key feature of the proposed approach is the explicit treatment of location-specific multiscale microstructure including gamma-prime precipitates, grain boundary structure and inclusions into a physics-based fatigue simulation tool. Because of the mechanistic nature of this approach, Rolls-Royce anticipates utilizing the calibrated and validated simulation tool for virtual rapid component design and for manufacturing process optimization. This significantly accelerates the development and qualification of aeroturbine disk component at lower cost than conventional statistical data driven methods. In addition to aeroturbine disk applications, the proposed simulation model and tool can be further extended to other areas such as land-based turbines and high-performance gears and bearings. Finally, materials design engineers can also use the proposed tool to develop innovative and robust materials specifically tailored to optimize the benefits of graded microstructures.