Download or read book Characterization and Modeling of Microstructure Development in Nickel base Superalloy Welds written by and published by . This book was released on 1999 with total page 5 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Alloy Design and Characterization of Strengthened Nickel based Superalloys for Additive Manufacturing written by Jinghao Xu and published by Linköping University Electronic Press. This book was released on 2021-01-28 with total page 63 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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.
Download or read book Characterization of Microstructure Evolution of Nickel Base Superalloys in Support of the Development of a Grain Growth Model written by Daniel Richard Corwin and published by . This book was released on 2007 with total page 224 pages. Available in PDF, EPUB and Kindle. Book excerpt: Abstract: I would like to thank Dr. Michael Mills, my adviser, for providing excellent support and guidance throughout this work. I'd also like to thank Eric Payton for his contributions and advice regarding practically all aspects of this project. Close collaboration with Dr. Yunzhi Wang, Gang Wang, and Ning Ma has been a very beneficial experience that has given me a valuable understanding of microstructure modeling. I am also very appreciative of the help received from Peter Sarosi, Libor Kovarik, and Ray Unocic regarding the transmission electron microscopy performed in this research. I wish to thank Dave Mourer, Deb Whitis, and Dan Wei at GE Aviation for providing guidance and direction in addition to making this research opportunity possible. Thanks to Ron Tolbert for helping procure the needed materials. I am grateful for the superior quality of the Campus Electron Optics Facility at OSU, and I'd like to specifically thank Cameron Begg and Henk Colijn for their assistance with SEM and TEM operation. This research was funded by GE Aviation.
Download or read book Weldability and Microstructure Development in Nickel base Superalloys written by and published by . This book was released on 2001 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The integrity of nickel-base superalloy single-crystal welds depends on the weld cracking tendency, weld metal dendrite selection process, stray crystal formation, and macro- and microstructure development. These phenomena have been investigated in commercial nickel-base superalloy single crystal welds. During electron beam and laser beam welding, transverse and longitudinal weld cracking occurred. However, the weld cracking tendency was reduced with preheating. Most of the dendritic growth pattern development in these welds can be explained by a geometric model. However, the welds also contained misoriented stray crystals, which were frequently associated with weld cracks. The formation of stray crystals was related to thermal and constitutional supercooling effects. Fine-scale elemental partitioning between[gamma] and[gamma][prime] phase was measured with atom-probe field-ion microscopy. Marked differences in partitioning characteristics in two welds were observed and are related to differences in cooling rates. In this paper, the modeling tools available to describe the above are reviewed.
Download or read book Superalloys 2012 written by Eric S. Huron and published by John Wiley & Sons. This book was released on 2012-10-02 with total page 952 pages. Available in PDF, EPUB and Kindle. Book excerpt: A superalloy, or high-performance alloy, is an alloy that exhibits excellent mechanical strength at high temperatures. Superalloy development has been driven primarily by the aerospace and power industries. This compilation of papers from the Twelfth International Symposium on Superalloys, held from September 9-13, 2012, offers the most recent technical information on this class of materials.
Download or read book Microstructure Development in Nickel Base Superalloys During Weld Thermal Cycle written by and published by . This book was released on 2000 with total page 5 pages. Available in PDF, EPUB and Kindle. Book excerpt: Welding plays an important role in the economical reuse and reclamation of used and failed nickel base superalloy blades. Previous research on microstructure development during laser beam welding of a single crystal CMSX4 alloy [Ref. l] showed non-equilibrium y/y(prime) microstructure development. In addition, the y(prime) precipitates were found to be irregular in shape and atom probe field ion microscopy illustrated the presence of diffusional concentration profile within the y phase in the as welded condition. To understand the above microstructure characteristics, y(prime) precipitation from y phase was investigated during continuous cooling from solutionizing temperature.
Download or read book Joining of Advanced and Specialty Materials II written by Mrityunjay Singh and published by ASM International(OH). This book was released on 2000 with total page 308 pages. Available in PDF, EPUB and Kindle. Book excerpt: The general themes of the 37 papers are brazing, welding, microjoining, and various other joining technologies; joint properties; microstructural characteristics; the science and technology of interfaces;, ceramic-metal joints; wetting and diffusion; and specific examples of successful applications.
Download or read book Transactions of JWRI written by 大阪大学. 溶接工学研究所 and published by . This book was released on 2002 with total page 664 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Welding Processes written by Radovan Kovacevic and published by BoD – Books on Demand. This book was released on 2012-11-21 with total page 454 pages. Available in PDF, EPUB and Kindle. Book excerpt: Despite the wide availability of literature on welding processes, a need exists to regularly update the engineering community on advancements in joining techniques of similar and dissimilar materials, in their numerical modeling, as well as in their sensing and control. In response to InTech's request to provide undergraduate and graduate students, welding engineers, and researchers with updates on recent achievements in welding, a group of 34 authors and co-authors from 14 countries representing five continents have joined to co-author this book on welding processes, free of charge to the reader. This book is divided into four sections: Laser Welding; Numerical Modeling of Welding Processes; Sensing of Welding Processes; and General Topics in Welding.
Download or read book Inertia Friction Welded Ni base Superalloys written by David Mahaffey and published by . This book was released on 2016 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Inertia friction welding of Ni-base superalloys is of increasing importance for future designs of turbine engines where the overall pressure ratio and operating temperatures are increased in an effort to improve efficiency. Ni-base superalloys are chosen for the hottest sections due to their inherent ability to retain good strength levels to very high fractions of their melting point. As model systems, the Ni-base superalloys LSHR and Mar-M247 were chosen for further welding and investigation. The LSHR is a powder-metallurgy alloy that is a surrogate for a bore material in a multi-alloy disk system. The Mar-M247 is a coarse-grain cast alloy that is a surrogate for a rim alloy. As the strength retention at elevated temperatures is advantageous for engine applications, it is disadvantageous for the production of sound welds. This effectively reduces the size of the processing window for these alloys. These alloys that are high in gamma prime formers are also prone to weld cracking issues. These factors make it necessary to utilize a process model to improve weld outcomes and reduce the amount of trial-and-error experimentation. Finite element modeling techniques and experimental weld process examination have led to insights into the complex interplay between the weld process parameters and their impact on post-weld microstructure, bond quality & character as well as mechanical properties. In effort to improve upon the predictive capability of the finite element process model, a number of weld parameters were examined. A minimum energy input bond criteria was formulated along with empirical relationships between the process parameters and weld behavior. Key input data for finite element process modeling was shown to include flow stress, coefficient of friction, and weld process efficiency. Strategies to estimate appropriate values for these key parameters were demonstrated and validated within the process model. The methodology to identify appropriate welding parameters, as well as their relative importance, was determined based on weld-trial data and resultant bond quality. The Ni-base superalloys LSHR and MarM247 were welded under varying conditions to provide experimental validation data. The finite element model results indicated the importance of the weld variables outlined above for accurate prediction of weld quality and upset. The investigation showed that the weld kinetic energy was not a sufficient criterion to set weld process parameters, and the effects of the efficiency of the weld equipment can have a profound impact on both the interpretation of model results and weld outcomes. It was also established that the weld upset behavior changes as a function of the energy multiplied by axial load. This parameter was also related to a minimum upset criterion.
Download or read book Welding and Joining of Aerospace Materials written by Mahesh Chaturvedi and published by Woodhead Publishing. This book was released on 2020-10-13 with total page 460 pages. Available in PDF, EPUB and Kindle. Book excerpt: Welding and Joining of Aerospace Materials, Second Edition, is an essential reference for engineers and designers in the aerospace, materials, welding and joining industries, as well as companies and other organizations operating in these sectors. This updated edition brings together an international team of experts with updated and new chapters on electron beam welding, friction stir welding, weld-bead cracking, and recent developments in arc welding. Highlights new trends and techniques for aerospace materials and manufacture and repair of their components Covers many joining techniques, including riveting, composite-to-metal bonding, and diffusion bonding Contains updated coverage on recently developed welding techniques for aerospace materials
Download or read book Scientific and Technical Aerospace Reports written by and published by . This book was released on 1995 with total page 704 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Modelling and Characterisation of the Microstructure in a Polycrystalline Nickel base Superalloy written by David Matthew Collins and published by . This book was released on 2012 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Solidification and Welding Metallurgy of Experimental Ni Base and Fe Base Superalloys Containing Nb Si and C written by John N. DuPont and published by . This book was released on 1997 with total page 644 pages. Available in PDF, EPUB and Kindle. Book excerpt: The solidification and weldability of experimental Ni base and Fe base superalloys containing Nb, Si, and C was studied using a combination of differential thermal analysis, quenching experiments, varestraint testing, and microstructural characterization techniques. The solidification reaction sequences responsible for microstructural development were found to be similar to those expected in the Ni-Nb-C ternary system. The solute rich interdendritic liquid exhibited two eutectic-type reactions at the terminal stages of solidification: $\rm L\to(\gamma + NbC$) and $\rm L\to(\gamma + Laves$). A pseudo ternary $\gamma$-Nb-C approach, modelled after the simple Ni-Nb-C system, was developed to provide a quantitative description of solidification behavior for these experimental alloys. Solute redistribution calculations in the model are based on a previous approach developed by Mehrabian and Flemings, with modifications made to account for the high diffusion rate of C in the solid. Solidification parameters for Nb and C were determined through DTA and electron probe microanalysis techniques and used as inputs to the model. Reasonable agreement is found between calculated volume fractions of the $\gamma$/NbC and $\gamma$/Laves constituents and those measured experimentally. The modelling results permit detailed descriptions of the relation between alloy composition and microstructural evolution during solidification. The results are also joined with experimental observations of fusion zone microstructures to determine the relation between alloy composition and solidification cracking susceptibility. A method is proposed for calculating the distribution of liquid in the solid + liquid zone as an aid to determining the individual effects of alloy composition on solidification cracking susceptibility.
Download or read book Welding Metallurgy and Weldability of Nickel Base Alloys written by John C. Lippold and published by John Wiley & Sons. This book was released on 2011-09-20 with total page 370 pages. Available in PDF, EPUB and Kindle. Book excerpt: The most up-to-date coverage of welding metallurgy aspects and weldability issues associated with Ni-base alloys Welding Metallurgy and Weldability of Nickel-Base Alloys describes the fundamental metallurgical principles that control the microstructure and properties of welded Ni-base alloys. It serves as a practical how-to guide that enables engineers to select the proper alloys, filler metals, heat treatments, and welding conditions to ensure that failures are avoided during fabrication and service. Chapter coverage includes: Alloying additions, phase diagrams, and phase stability Solid-solution strengthened Ni-base alloys Precipitation strengthened Ni-base alloys Oxide dispersion strengthened alloys and nickel aluminides Repair welding of Ni-base alloys Dissimilar welding Weldability testing High-chromium alloys used in nuclear power applications With its excellent balance between the fundamentals and practical problem solving, the book serves as an ideal reference for scientists, engineers, and technicians, as well as a textbook for undergraduate and graduate courses in welding metallurgy.
Download or read book Superalloys written by Matthew J. Donachie and published by ASM International. This book was released on 2002 with total page 439 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book covers virtually all technical aspects related to the selection, processing, use, and analysis of superalloys. The text of this new second edition has been completely revised and expanded with many new figures and tables added. In developing this new edition, the focus has been on providing comprehensive and practical coverage of superalloys technology. Some highlights include the most complete and up-to-date presentation available on alloy melting. Coverage of alloy selection provides many tips and guidelines that the reader can use in identifying an appropriate alloy for a specific application. The relation of properties and microstructure is covered in more detail than in previous books.
Download or read book Process Development and Characterization of an Oxide Dispersion Stabilized Nickel Base Superalloy written by Charles Hubert Smith and published by . This book was released on 1982 with total page 346 pages. Available in PDF, EPUB and Kindle. Book excerpt:
