Author: Charles Hubert SmithPublisher:
ISBN:
Category : Dispersion strengthening
Languages : en
Pages : 346
Book Description
Process Development and Characterization of an Oxide Dispersion Stabilized Nickel Base Superalloy
Author: Charles Hubert SmithPublisher:
ISBN:
Category : Dispersion strengthening
Languages : en
Pages : 346
Book Description
Alloy Design and Characterization of γ′ Strengthened Nickel-based Superalloys for Additive Manufacturing
Author: Jinghao XuPublisher: Linköping University Electronic Press
ISBN: 9179297269
Category :
Languages : en
Pages : 63
Book Description
Nickel-based superalloys, an alloy system bases on nickel as the matrix element with the addition of up to 10 more alloying elements including chromium, aluminum, cobalt, tungsten, molybdenum, titanium, and so on. Through the development and improvement of nickel-based superalloys in the past century, they are well proved to show excellent performance at the elevated service temperature. Owing to the combination of extraordinary high-temperature mechanical properties, such as monotonic and cyclic deformation resistance, fatigue crack propagation resistance; and high-temperature chemical properties, such as corrosion and oxidation resistance, phase stability, nickel-based superalloys are widely used in the critical hot-section components in aerospace and energy generation industries. The success of nickel-based superalloy systems attributes to both the well-tailored microstructures with the assistance of carefully doped alloying elements, and the intently developed manufacturing processes. The microstructure of the modern nickel-based superalloys consists of a two-phase configuration: the intermetallic precipitates (Ni,Co)3(Al,Ti,Ta) known as γ′ phase dispersed into the austenite γ matrix, which is firstly introduced in the 1940s. The recently developed additive manufacturing (AM) techniques, acting as the disruptive manufacturing process, offers a new avenue for producing the nickel-based superalloy components with complicated geometries. However, γ′ strengthened nickel-based superalloys always suffer from the micro-cracking during the AM process, which is barely eliminated by the process optimization. On this basis, the new compositions of γ′ strengthened nickel-based superalloy adapted to the AM process are of great interest and significance. This study sought to design novel γ′ strengthened nickel-based superalloys readily for AM process with limited cracking susceptibility, based on the understanding of the cracking mechanisms. A two-parameter model is developed to predict the additive manufacturability for any given composition of a nickel-based superalloy. One materials index is derived from the comparison of the deformation-resistant capacity between dendritic and interdendritic regions, while another index is derived from the difference of heat resistant capacity of these two spaces. By plotting the additive manufacturability diagram, the superalloys family can be categorized into the easy-to-weld, fairly-weldable, and non-weldable regime with the good agreement of the existed knowledge. To design a novel superalloy, a Cr-Co-Mo-W-Al-Ti-Ta-Nb-Fe-Ni alloy family is proposed containing 921,600 composition recipes in total. Through the examination of additive manufacturability, undesired phase formation propensity, and the precipitation fraction, one composition of superalloy, MAD542, out of the 921,600 candidates is selected. Validation of additive manufacturability of MAD542 is carried out by laser powder bed fusion (LPBF). By optimizing the LPBF process parameters, the crack-free MAD542 part is achieved. In addition, the MAD542 superalloy shows great resistance to the post-processing treatment-induced cracking. During the post-processing treatment, extensive annealing twins are promoted to achieve the recrystallization microstructure, ensuring the rapid reduction of stored energy. After ageing treatment, up to 60-65% volume fraction of γ′ precipitates are developed, indicating the huge potential of γ′ formation. Examined by the high-temperature slow strain rate tensile and constant loading creep testing, the MAD542 superalloy shows superior strength than the LPBF processed and hot isostatic pressed plus heat-treated IN738LC superalloy. While the low ductility of MAD542 is existed, which is expected to be improved by modifying the post-processing treatment scenarios and by the adjusting building direction in the following stages of the Ph.D. research. MAD542 superalloy so far shows both good additive manufacturability and mechanical potentials. Additionally, the results in this study will contribute to a novel paradigm for alloy design and encourage more γ′-strengthened nickel-based superalloys tailored for AM processes in the future.
American Doctoral Dissertations
Author: Publisher:
ISBN:
Category : Dissertation abstracts
Languages : en
Pages : 564
Book Description
Characterization of Phases in a Nickel Base Superalloy
Author: Shanker, KartikComprehensive Dissertation Index
Author: Publisher:
ISBN:
Category : Dissertations, Academic
Languages : en
Pages : 1116
Book Description
Characterization and Modeling of Microstructure Development in Nickel-base Superalloy Welds
Author: Metals Abstracts
Author: Scientific and Technical Aerospace Reports
Author: Japanese Science and Technology
Author: Powder Metallurgy of Superalloys
Author: G. H. GessingerPublisher: Elsevier
ISBN: 148319244X
Category : Technology & Engineering
Languages : en
Pages : 363
Book Description
Powder Metallurgy of Superalloys details the advancement of powder metallurgy in the context of producing superalloys. The book is comprised of nine chapters that cover the underlying principles of superalloys produced through powder metallurgy. The text first covers concerns in pre-alloyed dispersion-free powders, such as powder production and characterization; powder consolidation methods; and quality control and non-destructive evaluation of P/M superalloys. The next chapter talks about oxide-dispersion-strengthened superalloys. Next, the book discusses joining techniques for P/M superalloys and the practical applications of P/M superalloys. The title will be of great use to professionals in the materials manufacturing industry.