Udimet 720@ nickel-base superalloy is in current use as the material for the stage-two power turbine disk for the T800 engine. This alloy was selected because of its attractive level of tensile strength and resistance to low cycle fatigue (LCF). Advancements in novel isothermal forging technology have enabled the production of complex disk forgings called cluster forgings.A single cluster forging produces seven PT2 disks in a single forging operation. Coupled with recent advances in powder metallurgy (P/M) billet production featuring consolidation by HIP followed by extrusion, turbine disk forgings can be produced at a significant cost reduction as compared to single-piece hot die forged disks made from conventional cast/wrought billet. P/M Udimet 720 material displays excellent mechanical properties, competitive with other high strength disk alloys.Turbine disks produced from isothermally forged P/M Udimet 720 passed component test requirements established for the T800 engine. A significant cost reduction resulted from the use of this process.

Recent studies have identified thermo-mechanical conditions for powder UDIMET@alloy 72Oi which resulted in significantly higher ductility of HIP compacts [l]. In this process, the compact is produced by hot isostatic pressing (HIP) at temperatures just below the solidus of the alloy (slightly sub-solidus HIP or SS-HIP). The workability of the resulting as-HIPed material is high enough to allow billet conversion using conventional forging. This new process has the potential of reducing the cost of powdered metal (P/M) billet manufacturing. The results of the present study provide some insight on the mechanisms leading to the enhanced forgeability of the SS-HIP processed UDIMET alloy 720. In addition, a full-scale trial has shown that this new processing route has potential application for future production of high performance turbine disks, with equivalent microstructural and mechanical properties as parts manufactured with the conventional compact plus extrude plus isothermal forging route.

Advanced thermo-mechanical processing techniques have allowed the forging industry to improve upon new and existing alloys and to provide enhanced microstructures and properties for components. Processes that develop and control uniform grain sizes in components have long been desired by the aerospace industry. Also, processes that retain metallurgical strain from deformation processes have also shown great value. Retained metallurgical strain can provide two benefits: 1) assistance in precipitation processes, such as with DA718, and 2) increase the amount of strain hardening in the alloy and resultant component, such as IsoCon Waspaloy.718Plus™ is an alloy that has a relatively narrow processing window to produce uniform fine grain sizes. This new alloy has also shown gains in mechanical properties from direct age and retained metallurgical strain processing. An effort to apply IsoCon Alloy 718Plus™ has been undertaken. In this process a controlled isothermal forging step provides a highly refined preform geometry with uniform grain structure ("Iso" step in IsoCon). The preform is subsequently conventionally hammer forged ("Con" step) to develop the optimum metallurgical strain for enhanced mechanical properties. This paper will review the results from characterization work performed on IsoCon 718Plus™ Alloy forgings.

An emerging alloy that will fit the niche for low cost, high temperature applications is of great interest to the aerospace industry. One alloy, 718Plus™ has potential to replace high cost powder alloys in turbine engines and is the focus of on-going research. To investigate this potential alloy and application, an effort was undertaken to establish a manufacturing process route including hydraulic press forging and several heat treating methods. The paper will summarize the results obtained from press forgings given direct age and solution and age heat treatments. Issues relating to the alloy and TMP processing cycle will be assessed in regard to mechanical properties to determine the merits and/or limitations of this alloy. Superalloys 718, 625, 706 and Derivatives 2005 Edited by E.A. Loria

Fatigue crack growth is examined in AF2-lDA-6 over a wide spectrum of growth rates from lo-* to 10m6 m/cycle for two mean stress values (R = 0.7 and 0.05) and two frequencies (10 and 2 Hz) at 649 "C. The effects of one processing parameter, the cooling rate from the solution heat treatment, on Paris law growth rates is examined. In addition, the effects of changes in grain size on the same parameters are examined. No effect of cooling rate horn solution heat treatment or of grain size on Paris law crack growth is seen for high R ratio tests at 10 Hz. However, low R ratio tests at lower frequency, 2 Hz, indicate that crack growth rates can vary with microstructure. Namely, crack growth rates are higher for a slow cooling rate of 34 'C/mm for both the ASTM 10 % and 6 average grain sizes. The effect is more dramatic for the smaller grain size. Crack growth rates in that material, i.e. AF2-lDA-6 cooled at the slow rate with a grain size of ASTM 10 l/2, exhibited the highest growth rate of all when R=O.O5 and the sinusoidal load frequency was 2 Hz. Some implications of these results on forging of such alloys are discussed.