A. DeBiccari, Pratt & Whitney, East Hartford, CT
Static superalloy components, such as diffuser and turbine cases, are among the most expensive parts found in gas turbine engines. Drivers for these high costs include inefficient material usage (high buy-to-fly ratios) and machining costs for forgings and material, mold costs, and re-work for castings. The use of additive manufacturing has the potential to attack multiple cost drivers simultaneously, resulting in significant cost and lead-time reductions.
The Metals Affordability Initiative (MAI) funded an investigation of additive manufacturing for superalloy cases. Electron beam wire deposition, laser powder deposition, and a gas-tungsten arc wire feed methods are being evaluated for both technical and economic feasibility. The initial phase of this study showed that all three processes under investigation were capable of making deposits that met the established microstructural and deposition quality standards. Preliminary economic analysis showed that cost savings of 30-40% are achievable when compared to conventional ring rolling methods.
After establishing deposition quality and economic feasibility, the next step towards implementation is to demonstrate the deposited material attains the mechanical properties required of the targeted component(s). Tensile, creep/stress rupture, and low cycle fatigue properties were evaluated for bulk deposits and the deposit/substrate interface for all three deposition methods under investigation. In the bulk deposits, properties were evaluated in three directions; parallel to the deposition direction and normal to the deposition direction both in and out of the deposition plane. At the deposition/substrate interface, properties were evaluated normal to the interface. All deposits and substrates were IN718. These mechanical properties were compared to baseline cast IN718 values, the established minimum requirements.
This talk describes the details and results of this mechanical property evaluation. Additionally, updates to the cost models based and associated cost saving estimates will also be discussed. Finally, additional tasks required for implementing additive manufacturing into production will be addressed.
Summary: This presentation will summarize nickel additive work performed under the Metals Affordability Initiative.
