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Advanced Characterization of Defect and Grain Structures in Net-Shape Hot Isostatically Pressed IN-718

Georgin, Benjamin M
http://rave.ohiolink.edu/etdc/view?acc_num=osu1606908765003814

Abstract Details

2020, Doctor of Philosophy, Ohio State University, Materials Science and Engineering.
Much effort has been directed over the past several decades towards net-shape manufacturing of nickel-base superalloys which are difficult to conventionally process because of their compositional complexity. Net-shape hot isostatic pressing (NS-HIP) has been employed for the last fifty years for consolidation of superalloys and has numerous advantages when compared with traditional processing. These include very efficient use of material, refined microstructure without prominent texture or residual stresses, and the absence of porosities. Disadvantages include the cost of sacrificial tooling and the presence of defect networks in consolidated material. These networks of defects, designated as prior particle boundaries (PPB) because they originate at the surfaces of powder stock, contribute to a scatter or deficit in mechanical properties, which in the past has disqualified NS-HIP materials from use in critical aerospace applications. Studies in this work have shown that the HIP:ing of superalloy powders of the same nominal composition, but processed with different conditions, yield quite different microstructures and properties. The origins of these differences, such as atomization method, cleanliness of the material, powder size and shape, and grain structure have been examined using various characterization techniques. This work has focused on the characterization of microstructure and defects of IN-718 in rapidly solidified powders, at intermediate stages during HIP, and in the as-HIP condition. Novel methods for characterizing and quantifying defects in superalloys, with an emphasis on the contrast mechanisms in low voltage in-column scanning electron microscopy are presented. An approach has been developed for net-shape HIP processing of IN-718 with improved microstructure and tolerance for defects.
Hamish Fraser (Advisor)
Yunzhi Wang (Committee Member)
Steven Niezgoda (Committee Member)
193 p.
Materials Science
superalloy; hot isostatic pressing; IN-718; scanning electron microscopy; prior particle boundaries; recrystallization; consolidation; powder metallurgy; physical metallurgy

Recommended Citations

Citations

  • Georgin, B. M. (2020). Advanced Characterization of Defect and Grain Structures in Net-Shape Hot Isostatically Pressed IN-718 [Doctoral dissertation, Ohio State University]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=osu1606908765003814

    APA Style (7th edition)

  • Georgin, Benjamin. Advanced Characterization of Defect and Grain Structures in Net-Shape Hot Isostatically Pressed IN-718. 2020. Ohio State University, Doctoral dissertation. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=osu1606908765003814.

    MLA Style (8th edition)

  • Georgin, Benjamin. "Advanced Characterization of Defect and Grain Structures in Net-Shape Hot Isostatically Pressed IN-718." Doctoral dissertation, Ohio State University, 2020. http://rave.ohiolink.edu/etdc/view?acc_num=osu1606908765003814

    Chicago Manual of Style (17th edition)

osu1606908765003814
170
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This open access ETD is published by The Ohio State University and OhioLINK.