Turbine blades are traditionally manufactured using ?'-precipitation strengthened nickel-based superalloys, such as Inconel 738 low carbon (IN738LC), due to their mechanical properties, e.g., fatigue properties and creep strength, at elevated temperatures, as well as their oxidation and corrosion resistance. New turbine blade designs also incorporate thermal barrier coatings and internal cooling pathways to safely push turbine inlet temperatures above the melting point of these superalloys, leading to improved turbine engine efficiency and increased power output. To achieve these inlet temperatures without melting the blades, modern gas turbine engines bleed air from the engine compressor through cooling channels within the turbine blades to extend engine lifetime. However, the complexity of the internal cooling networks for turbine blades are limited by the conventional casting process. Cellular lattice structures, which may provide improved cooling efficiency and additional weight savings, are currently not feasible. Recent advances in additive manufacturing (AM) technology, e.g., laser powder bed fusion (LPBF), have enabled the fabrication of near-net shape structures with complex geometries, e.g., cellular lattice structures. Therefore, LPBF is a potential manufacturing alternative to traditional casting process that can both enable more complex turbine blade designs with improved cooling efficiency and reduce lead times. Unfortunately, ?-precipitation strengthened nickel-based superalloys such as IN738LC are prone to cracking during the LPBF process due to the high temperature gradients and rapid solidification. Materials Sciences LLC (MSC) in partnership with the National Center for Additive Manufacturing Excellence (NCAME) at Auburn University (AU) propose the development of optimal AM process parameters for LPBF of IN738LC, to achieve geometric and material control while minimizing defects. Additionally, MSC and NCAME propose the fabrication of generic prototypes with internal cellular lattice structures to demonstrate the manufacturing feasibility of more complex internal networks for improved turbine blade cooling efficiency.
Benefit: The anticipated benefits of the program include a demonstration of the Additive Manufacturing (AM) Viability of Turbine Blade Materials, e.g., Inconel 738LC, and establishing Design for Manufacturability of Innovative Complex Designs for Increased Cooling Efficiency. Key outcomes of the SBIR program include: (1) Optimal AM parameters for fabricating turbine blades with fatigue critical properties at elevated temperatures; (2) Commercialized alloy and production methodology transitioned to a suitable industrial producer; (3) Cellular lattice structures for combined conductive and convective heat transfer efficiency while meeting performance requirements such as low weight, high stiffness, and high strength; (4) Topology-optimization based design which satisfies required operating conditions-e.g., channel size, pressure drop tolerance, cooling efficiency-of Original Equipment Manufacturers for integration to existing platforms. Commercial applications include turbine engines, produced by Original Equipment Manufacturers (OEMs) such as GE Aviation, Rolls Royce, Pratt & Whitney, for integration with existing platforms, such as Lockheed Martin or Boeing. Outside of the defense market, interest is anticipated from a number of commercial industries where AM is increasingly used to support new and aging supply chains. Target industries with high temperature applications include aerospace, automotive, oil & gas, utilities, and shipping.
Keywords: turbine components, turbine components, materials databases, additive manufacturing, cellular lattice structures, topology optimization, cooling network, defect minimization, laser powder bed fusion
