Author: Birhan Sefer
Publisher:
ISBN:
Category :
Languages : en
Pages : 183
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Book Description
This thesis covers investigation of the surface phenomena of Ti-6Al-4V and Ti-6Al-2Sn-4Zr-2Mo alloys related with oxidation at elevated temperature and corrosion during chemical treatment in hydrofluoric-nitric acid (HF/HNO3) solutions. The explored phenomena are related to manufacturing and service conditions of aero-engine components. During manufacturing and operation, the alloys are sunjected to elevated temperatures in oxygen environment. In such conditions an oxide on the surface and an oxygen enriched layer below the oxide, commonly referred as alpha-case is formed. Alpha-case is a hard and brittle layer that is detrimental to the mechanical properties and must therefore be completely eliminated. A conventional method for elimination of alpha-case is chemical processing in HF/HNO3 solutions, i.e. chemical milling. Isothermal oxidation treatments in air at 500, 593 and 700 oC for up to 500 hours were carried out in this thesis. Both alloys developed rutile type of oxide structure and Ti-6Al-2Sn-4Zr-2Mo exhibited stronger oxidation resistance than Ti-6Al-4V. Transition from parabolic to linear oxidation rate was observed at 700 oC and = 200 hours for both alloys. The difference in the oxidation kinetics of the two alloys is suggested to be related with the chemical composition of the alloys. The oxygen enriched layer, i.e. alpha-case layer, was characterised and its thickness was measured using conventional metallographic and microscopic techniques. The parabolic rate constants, the oxygen diffusion parameters and activation energies were estimated in the temperature range of 500-700 oC for both alloys. Moreover, the oxidation for 500 hours at 700 oC resulted in microstructural changes and element re-distribution. The bulk and alpha-case layer hardness at micro- and nano-scale were measured using microhardness and nanoindentation techniques. The alpha-case layer had higher hardness due to the solid solution strengthening effect of the diffused oxygen. The effect of chemical milling in 1:11 HF/HNO3 solution on the surface integrity, and the influence on low cycle fatigue (LCF) strength of cast Ti-6Al-2Sn-4Zr-2Mo alloy was investigated. Five and sixty minutes chemical processing times and three imposed total strain ranges in fatigue tests were evaluated. Significant drop in fatigue life was observed for the samples etched before LCF testing, as compared to the non-etched samples. The influence from etching was found to be most detrimental for fatigue samples tested at the lowest strain ranges. The fatigue life reduction was correlated with the number of crack initiation sites. Multiple crack initiation sites were observed for the etched samples, whereas only one crack initiation site was discerned in the non-etched samples. Inspection of the surface of the etched samples revealed selective and severely etched prior ß grain boundaries and pit formation at the triple joints of the prior ß grain boundaries. These surface defects were considered as stress raisers promoting an earlier fatigue crack initiation. The influence of two molar concentration ratios of HF and HNO3 acids (1:3 and 1:11) on the corrosion behaviour of cast Ti-6Al-4V and Ti-6Al-2Sn-4Zr-2Mo were investigated by electrochemical and atomic force microscopy (AFM) techniques. The corrosion of the two alloys was a function of the concentration ratio of the acids and also of the alloys¿ chemical compositions. The AFM measurements showed faster dissolution rate of the a-phase than the ß-phase in the Widmanstätten microstructure. It was considered that the reason for this is formation of local micro-galvanic cells between the phases. Moreover, the Volta-potential was measured using scanning Kelvin probe force microscopy (SKPFM) and the obtained maps revealed difference in the Volta-potential between the a- and the ß-laths in both alloys. This observation strengthened the likelihood for formation and operation of micro-galvanic cells between the phases.
Author: J. D. Jackson
Publisher:
ISBN:
Category : Titanium
Languages : en
Pages : 54
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Book Description
Author: Christoph Leyens
Publisher: John Wiley & Sons
ISBN: 3527605207
Category : Technology & Engineering
Languages : de
Pages : 532
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Book Description
This handbook is an excellent reference for materials scientists and engineers needing to gain more knowledge about these engineering materials. Following introductory chapters on the fundamental materials properties of titanium, readers will find comprehensive descriptions of the development, processing and properties of modern titanium alloys. There then follows detailed discussion of the applications of titanium and its alloys in aerospace, medicine, energy and automotive technology.
Author:
Publisher:
ISBN:
Category : Aeronautics
Languages : en
Pages : 952
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Book Description
Author: Matthew J. Donachie
Publisher: ASM International
ISBN: 161503062X
Category : Technology & Engineering
Languages : en
Pages : 381
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Book Description
Designed to support the need of engineering, management, and other professionals for information on titanium by providing an overview of the major topics, this book provides a concise summary of the most useful information required to understand titanium and its alloys. The author provides a review of the significant features of the metallurgy and application of titanium and its alloys. All technical aspects of the use of titanium are covered, with sufficient metals property data for most users. Because of its unique density, corrosion resistance, and relative strength advantages over competing materials such as aluminum, steels, and superalloys, titanium has found a niche in many industries. Much of this use has occurred through military research, and subsequent applications in aircraft, of gas turbine engines, although more recent use features replacement joints, golf clubs, and bicycles.Contents include: A primer on titanium and its alloys, Introduction to selection of titanium alloys, Understanding titanium's metallurgy and mill products, Forging and forming, Castings, Powder metallurgy, Heat treating, Joining technology and practice, Machining, Cleaning and finishing, Structure/processing/property relationships, Corrosion resistance, Advanced alloys and future directions, Appendices: Summary table of titanium alloys, Titanium alloy datasheets, Cross-reference to titanium alloys, Listing of selected specification and standardization organizations, Selected manufacturers, suppliers, services, Corrosion data, Machining data.
Author: W. A. Riehl
Publisher:
ISBN:
Category : Oxygen
Languages : en
Pages : 136
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Book Description
This study was undertaken to develop information on which a knowledgeable decision could be based concerning the use of titanium for construction of thin walled LOX tanks. The primary goals were to investigate the reactions of titanium alloys with oxygen under a variety of conditions associated with space vehicles, and to determine if the titanium could be treated or coated in some fashion to eliminate such hazards.
Author: Committee on New Materials for Advanced Civil Aircraft
Publisher: National Academies Press
ISBN: 0309588782
Category : Technology & Engineering
Languages : en
Pages : 99
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Book Description
The major objective of this book was to identify issues related to the introduction of new materials and the effects that advanced materials will have on the durability and technical risk of future civil aircraft throughout their service life. The committee investigated the new materials and structural concepts that are likely to be incorporated into next generation commercial aircraft and the factors influencing application decisions. Based on these predictions, the committee attempted to identify the design, characterization, monitoring, and maintenance issues that are critical for the introduction of advanced materials and structural concepts into future aircraft.
Author: R. I. Jaffee
Publisher: Elsevier
ISBN: 1483158810
Category : Technology & Engineering
Languages : en
Pages : 1225
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Book Description
The Science, Technology and Application of Titanium contains the proceedings of an International Conference organized by the Institute of Metals, The Metallurgical Society of AIME, and the American Society for Metals in association with the Japan Institute of Metals and the Academy of Sciences of the USSR and held at the Royal Festival Hall in London, on May 21-24, 1968. The papers explore scientific and technological developments as well as applications of titanium and cover topics ranging from processing of titanium to its chemical and environmental behavior, physics, thermodynamics, and kinetics. Deformation and fracture, phase transformations and heat treatment, and alloying are also discussed. This book is comprised of 114 chapters and begins with an overview of the titanium industry in Europe and the United States. The reader is then introduced to primary and secondary fabrication of titanium; corrosion and oxidation; physical properties of titanium alloys; interaction of titanium with elements of the periodic system; and elastic interactions between dislocations and twin and grain boundaries in titanium. The crystallography of deformation twinning in titanium is also examined, along with superplasticity and transformation plasticity in titanium. The remaining chapters focus on interstitial strengthening of titanium alloys; mechanism of martensitic transformation in titanium and its alloys; phase relationships in titanium-oxygen alloys; strengthening of titanium alloys by shock deformation; and titanium hot forming. This monograph will be of interest to chemists and metallurgists.
Author: Flake C Campbell Jr
Publisher: Elsevier
ISBN: 0080462359
Category : Technology & Engineering
Languages : en
Pages : 617
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Book Description
The rapidly-expanding aerospace industry is a prime developer and user of advanced metallic and composite materials in its many products. This book concentrates on the manufacturing technology necessary to fabricate and assemble these materials into useful and effective structural components. Detailed chapters are dedicated to each key metal or alloy used in the industry, including aluminum, magnesium, beryllium, titanium, high strength steels, and superalloys. In addition the book deals with composites, adhesive bonding and presents the essentials of structural assembly. This book will be an important resource for all those involved in aerospace design and construction, materials science and engineering, as well as for metallurgists and those working in related sectors such as the automotive and mass transport industries. Flake Campbell Jr has over thirty seven years experience in the aerospace industry and is currently Senior Technical Fellow at the Boeing Phantom Works in Missouri, USA.* All major aerospace structural materials covered: metals and composites* Focus on details of manufacture and use* Author has huge experience in aerospace industry* A must-have book for materials engineers, design and structural engineers, metallurgical engineers and manufacturers for the aerospace industry
Author: Bhaskar Dutta
Publisher: Butterworth-Heinemann
ISBN: 0128047836
Category : Technology & Engineering
Languages : en
Pages : 96
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Book Description
Additive Manufacturing of Titanium Alloys: State of the Art, Challenges and Opportunities provides alternative methods to the conventional approach for the fabrication of the majority of titanium components produced via the cast and wrought technique, a process which involves a considerable amount of expensive machining. In contrast, the Additive Manufacturing (AM) approach allows very close to final part configuration to be directly fabricated minimizing machining cost, while achieving mechanical properties at least at cast and wrought levels. In addition, the book offers the benefit of significant savings through better material utilization for parts with high buy-to-fly ratios (ratio of initial stock mass to final part mass before and after manufacturing). As titanium additive manufacturing has attracted considerable attention from both academicians and technologists, and has already led to many applications in aerospace and terrestrial systems, as well as in the medical industry, this book explores the unique shape making capabilities and attractive mechanical properties which make titanium an ideal material for the additive manufacturing industry. - Includes coverage of the fundamentals of microstructural evolution in titanium alloys - Introduces readers to the various Additive Manufacturing Technologies, such as Powder Bed Fusion (PBF) and Directed Energy Deposition (DED) - Looks at the future of Titanium Additive Manufacturing - Provides a complete review of the science, technology, and applications of Titanium Additive Manufacturing (AM)
