The Versatile Affordable Advanced Turbine Engine (VAATE) program has been supporting the development of Alloy 10, a gasatomized powder metal (PM) superalloy. Funding for the program was provided by U.S. Air Force Research Laboratory (AFRL).Honeywell International, Rolls Royce -Allison Advanced Development Company (AADC), and Williams International have been jointly developing Alloy 10 for small and large gas turbine engine applications. Alloy 10 is a demonstrated industry leader in high temperature creep resistance, and has been produced using production-scale equipment for high pressure turbine disk applications. To address cost issues, the VAATE Alloy 10 project evaluated the relative differences between material densified by hot isostatic pressing (as-HIP) and material produced by extrusion followed by isothermal forging. The program was completed as a series of four tasks: (i) chemistry optimization, (ii) as-HIP compaction, (iii) HIP compaction plus isothermal forging for small engine applications, and (iv) extrusion plus isothermal forging for large engine applications. This report provides the status of the program, microstructures typical of the various Alloy 10 product forms, and a summary of initial mechanical properties data.
The 718 family of nickel-base superalloys is used extensively in the design of critical aerospace components, namely in the hot section disks of gas turbine engines. The reliability of such components is often dependent upon, among other factors, their as-machined surface integrity. Surface integrity is often related to tool-surface interactions. The interactions may result in varying degrees of carbide cracking (possibly resulting in matrix cracking), carbide pull-outs, surface tearing, surface roughness, and grain distortion.
Fine Grain Alloy 718 is a relatively cost effective turbine and compressor disk alloy with superior yield strength and low cycle fatigue properties. An understanding of Alloy 718's response to environmental and temperature conditions under sustained peak or dwell conditions is a requirement for assessing actual in-service capability. This is especially critical when the disk operating conditions exceed historical engine experience with Alloy 718. This paper presents a detailed review of experimental dwell low cycle fatigue and cyclic crack growth results for fine grain alloy 718. The experimental fatigue results combined with the observed physical initiation and propagation mechanisms were used to develop a comprehensive life prediction system for fine grain Alloy 718 turbine disk.
PM Alloy N625 is used primarily in environments where high strength and corrosion resistance are required. The pre-alloyed powder is manufactured by inert gas atomization and consolidated by hot isostatic pressing (HIP). This study used dimensionless parameters to directly compare the microstructure evolution of this alloy with the evolution of the geometric models used for HIPing. The results suggest systematic differences between the microstructure evolution of the experiments and the model geometries.
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