E. A. Ott, GE Transportation, Cincinnati, OH; H. Sizek, Air Force Research Laboratory, Wright-Patterson AFB, OH

Summary:

Mechanical property balance, malleability, and weldability of Alloy 718 have driven widespread utilization across the aerospace and non-aerospace industries over nearly 50 years; however, temperature limitations due to metastability are typically inadequate for applications above about 1200°F (650°C). As a result, other more costly and difficult to process alloys, like Waspaloy, are used in such applications. These alloys, strengthened primarily by the gamma prime phase, are also more sensitive to weld-related cracking than Alloy 718. As part of the Metals Affordability Initiative CORE Program, several alternate alloys were identified and evaluated for aircraft engine static structural component applications for use temperatures of at least 1300°F (705°C). The application-integrated project team consisting of engine manufacturers, GE, Honeywell, and Pratt & Whitney; forgers, Firth Rixson Viking and Ladish Company; primary metal producers, Allvac and Carpenter Technology; in combination with the Wright Patterson Air Force Base Materials Laboratory, selected the Allvac-developed 718Plus™ alloy chemistry for scale-up and validation. Subscale and full-scale experiments confirmed that processability and weldability of this alloy were significantly improved relative to Waspaloy, and more similar to that of Alloy 718. Complex rolled ring shapes varying in size from less than 50 pounds to nearly 500 pounds have been processed validating the processing advantages of this alloy. Mechanical assessment suggests nearly equivalent strength levels and stability to Waspaloy to 1300°F (705°C) have also been achieved along with an acceptable balance of other properties. This presentation will summarize the successful processing, weldability, and mechanical property evaluation efforts performed under this project and the progress toward industrial implementation of this alloy.