Skip to Main Content
 

Global Search Box

 
 
 
 

Files

File List


20943.pdf (18.15 MB)

ETD Abstract Container

Abstract Header

Physical Metallurgy of Rene 65, a Next-Generation Cast and Wrought Nickel Superalloy for use in Aero Engine Components

Wessman, Andrew E
http://rave.ohiolink.edu/etdc/view?acc_num=ucin1467126769

Abstract Details

2016, PhD, University of Cincinnati, Engineering and Applied Science: Materials Science.
Advancements in the design of turbine engines are in large part made possible by advancements in the capability of nickel based superalloys. Greater temperature and stress capabilities in these materials allow for increased operating temperatures and speeds in the engines, which lead to increased fuel efficiency. Early jet engines were built using austenitic stainless steels, and moved to cast and wrought nickel alloys as higher temperatures were required. By the 1970s, the state of the art nickel superalloy was Inconel 718, which is strengthened by the Ni3Nb phase known as gamma double prime. This alloy performs well and is still in heavy use in turbine engines at temperatures up to approximately 650°C (1200°F), but at higher temperatures the main strengthening precipitate phase, γ’’, is thermodynamically unstable, resulting in a loss of strength following exposure to high temperature. Further advancements in nickel superalloys generally involved alloys strengthened by the Ni3Al phase known as γ'. This precipitate is stable at much higher temperatures, but due to compositional segregation in cast and wrought processing, these alloys were processed using powder metallurgy methods, at considerable economic cost. This study will examine the microstructure of a next generation cast and wrought nickel superalloy that can provide increased temperature capability relative to Inconel 718, at lower cost than powder metallurgy superalloys. The alloy chemistry is similar to that of the powder metallurgy superalloy Rene 88DT, with changes to make it better suited for cast and wrought processing and with a ifferent processing route from billet processing through to final part heat treatment. It is a gamma prime strengthened superalloy. The alloy has been recently introduced into service in turbine engines by GE Aviation as the alloy Rene 65, the composition of which is shown below In this work, the following has been shown: Rene 65 γ precipitate structure is related to thermal history of the material, and the particle size distribution can be predicted using established models for precipitation in superalloys Rene 65 shows a predictable microstructural response to high temperature exposure, with γ’ coarsening that is predictable using the Lifshitz-SlyozovWagner theory. Rene 65 tensile and creep capability are determined by the γ’ distribution, and the yield strength of the alloy can be predicted using a critical resolved shear stress approach This work has also provided a comprehensive overview of the structure of Rene 65 during various processing stages and following thermal exposures expected during use of the alloy in turbine engines. The processing-structure-property relationships for this advanced cast and wrought nickel based superalloy developed for use in turbine engine applications are described in detail, which will serve as a useful guide in the manufacture and use of components made from the alloy, and contribute to the overall body of knowledge in the field of metallurgy of nickel based superalloys.
Vijay Vasudevan, Ph.D. (Committee Chair)
Kenneth R. Bain, Ph.D. (Committee Member)
Rodney Roseman, Ph.D. (Committee Member)
Jainagesh Sekhar, Ph.D. (Committee Member)
Materials Science

Recommended Citations

Citations

  • Wessman, A. E. (2016). Physical Metallurgy of Rene 65, a Next-Generation Cast and Wrought Nickel Superalloy for use in Aero Engine Components [Doctoral dissertation, University of Cincinnati]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1467126769

    APA Style (7th edition)

  • Wessman, Andrew. Physical Metallurgy of Rene 65, a Next-Generation Cast and Wrought Nickel Superalloy for use in Aero Engine Components. 2016. University of Cincinnati, Doctoral dissertation. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=ucin1467126769.

    MLA Style (8th edition)

  • Wessman, Andrew. "Physical Metallurgy of Rene 65, a Next-Generation Cast and Wrought Nickel Superalloy for use in Aero Engine Components." Doctoral dissertation, University of Cincinnati, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1467126769

    Chicago Manual of Style (17th edition)

ucin1467126769
1,604
© 2016, all rights reserved.
This open access ETD is published by University of Cincinnati and OhioLINK.