Download or read book Fine Grain Aluminum Superplasticity written by C. H. Hamilton and published by . This book was released on 1980 with total page 66 pages. Available in PDF, EPUB and Kindle. Book excerpt: FINE GRAINED 7475 ALUMINUM ALLOY SHEET WAS EVALUATED FOR ITS SUPERPLASTIC PROPERTIES AND POTENTIAL FOR SUPERPLASTIC FORMING. The sheet alloy was specially processed by the ALCOA Technical Laboratory utilizing procedures prescribed by the contractor to achieve a fine grain size. The grain size measurements on this sheet alloy after complete recrystallization revealed a short transverse dimension of 7.8 microm and longitudinal and long transverse dimension of 14 microm. Subsequent grain growth studies showed that this fine grain size developed is quite stable at temperatures as high as 516 C . High temperature testing was conducted over the temperature range of 427 C to 516 C in order to establish the strain rate sensitivity of flow stress, strain hardening characteristics, and total elongation capabilities. Superplastic forming tests were also conducted utilizing commonly used gas pressure forming methods. Small demonstration parts were formed over a range of strain rates and thinning characteristics evaluated. Metallographic evaluation of tensile test specimens and formed parts revealed the tendency of the alloy to form internal voids, or cavities, at large strains. The cavitation appears to be sensitive to the conditions of deformation, being minimized at the higher temperature and lower strain rates.
Download or read book Superplasticity in Aluminum Alloys written by and published by . This book was released on 1997 with total page 13 pages. Available in PDF, EPUB and Kindle. Book excerpt: We have characterized in the Al-Mg system the microstructure and mechanical properties of a cold-rolled Al-6Mg-0.3Sc alloy. The alloy exhibited superplasticity at relatively high strain rates (about 10-2 s-1). At a strain rate of 10-2 s-1 there exists a wide temperature range (475-520'C) within which the tensile elongation is over 1000%. There also exists a wide strain rate range (10-3 - 10-1 s-1) within which the tensile elongation is over 500%. The presence of Sc in the alloy results in a uniform distribution of fine coherent Al3SC precipitates which effectively pin grain and subgrain boundaries during static and continuous recrystallization. As a result, the alloy retains its fine grain size (about 7 micron), even after extensive superplastic deformation (>1000%). During deformation, dislocations Mg with a high Schmidt factor slip across subgrains but are trapped by subgrain boundaries, as a result of the strong pining of Al3Sc. This process leads to the conversion of low-angled subgrain boundaries to high-angled grain boundaries and the subsequent grain boundary sliding, which produces superelasticity. A model is proposed to describe grain boundary sliding accommodated by dislocation glide across grains with a uniform distribution of coherent precipitates. The model predictions is consistent with experimental observations.
Download or read book High Temperature Flow and Failure Processes in a Fine grained Superplastic 7475 Aluminum Alloy written by Mahidhara Kameswara Rao and published by . This book was released on 1985 with total page 642 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Aluminum Lithium Alloys written by S. Balasivanandha Prabu and published by Elsevier Inc. Chapters. This book was released on 2013-09-20 with total page 51 pages. Available in PDF, EPUB and Kindle. Book excerpt: Since the late 1950s, lithium is being used as an alloying element in aluminum. Their excellent ductility, which allows superplastic forming, along with their ability to decrease the density, makes aluminum-lithium alloys a primary choice for many structural applications in aerospace industry. This chapter initially discusses the processes and mechanisms that give rise to significant plasticity/Superplasticity in these alloy systems. The superplastic behavior of Al-Li alloys and their applications in forming are then discussed. The thickness variation during superplastic forming strongly depends on the peak strain rate sensitivity index (m) of the material, and an increase in the m value reduces the thickness variation in the formed component. The factors that help increase the value of m are enumerated. Superplastic forming is carried out at temperatures ≥ 0.5 Tm (Tm is the absolute melting temperature), often closer to 0.7 − 0.8 Tm. Significant cavitation and grain growth are present at such high temperatures. This has ushered in low temperature superplastic forming by the production of ultra-fine grain sizes via dispersion strengthening and severe plastic deformation (SPD). The promise of superplastic forming of Al-Li alloys for the future and the factors including cost that limit the use of Al-Li alloys are also discussed.
Download or read book Superplasticity of Fine Grained Aluminum Alloys written by José M. Belzunce and published by . This book was released on 1983* with total page 80 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Ultrafine Grained Materials II written by Yuntian Theodore Zhu and published by John Wiley & Sons. This book was released on 2013-09-25 with total page 886 pages. Available in PDF, EPUB and Kindle. Book excerpt: Proceedings of a symposium sponsored by the Shaping and Forming Committee of the Materials Processing and Manufacturing Division (MPMD) and the Mechanical Behavior Committee (Jt. SMD/ASM-MSCTS) of the Structural Materials Division (SMD) of TMS (The Minerals, Metals & Materials Society) and held during the 2002 TMS Annual Meeting in Seattle, Washington February 17-21,2002.
Download or read book Analysis of the Transition in Deformation Mechanisms in Superplastic 5083 Aluminum Alloys by Orientation Imaging Microscopy written by James W. Harrell and published by . This book was released on 2001-09-01 with total page 95 pages. Available in PDF, EPUB and Kindle. Book excerpt: Recently developed Orientation Imaging Microscopy (OIM) methods have been applied to the analysis of microstructure and microtexture of 5083 aluminum alloy materials that have been processed to enable superplasticity. The phenomenon of superplasticity allows economical forming of complex components while retaining the high strength- and stiffness-to-weight ratios characteristic of aluminum alloys used in automotive, aerospace and military applications. Superplasticity requires fine grains with high-angle boundaries and resistance to failure by cavitation. OIM permits grain-specific orientation determination and quantitative assessment of the grain-to-grain disorientation distribution as well as grain size measurement in materials. The current work offers significant new insights into the development and response of superplastic microstructures; in particular, OIM data may be employed to delineate the transition from slip to grain boundary sliding in superplastic 5083 materials.
Download or read book Low Temperature Superplasticity in Aluminum Alloys Processed by Equal Channel Angular Pressing written by and published by . This book was released on 2002 with total page 7 pages. Available in PDF, EPUB and Kindle. Book excerpt: Equal-channel angular pressing (ECAP) was applied to achieve grain refinement of Al-3 mass%Mg alloys containing 0.2 mass%Sc. 0.2 mass%Fe or 0.1 mass%Zn The thermal stability of the fine-grained structures was examined by conducting static annealing experiments. The fine grain sizes produced by ECAP were essentially retained up to a temperature of 523K for the Fe-containing and Zr-containing alloys and up to a temperature as high as 773 K for the Sc-containing alloy. The three alloys with Sc. Fe and Zr additions were pulled to failure in tension at 523 K corresponding to 0.59Tm. where Tm is the absolute melting point of the alloy, and maximum elongations of 640%, 370% and 390% were obtained at an initial strain rate of 3.3 x l0-4 s-1 respectively. Such elongations resulted in more than three times or approximately twice the elongation achieved in a binary Al-3%M alloy. It is shown that either Fe or Zr may be used as an alternative element in place of Sc to attain low temperature superplasticity. Tensile testing was also conducted on the Sc-containing ternary alloy at a temperature as low as 473K corresponding to O.54Tm. A maximum elongation of 420% was attained at an initial strain rate of 3.3 % l0-4 s-1. This appears to be the lowest homologous temperature reported to date for superplasticity of Al-based alloys.
Download or read book Analysis of Grain Refinement and Superplasticity in Aluminum Magnesium Alloys written by Ahmed Ahmed Abou-Salama and published by . This book was released on 1987 with total page 167 pages. Available in PDF, EPUB and Kindle. Book excerpt: Previous research had demonstrated superplastic behavior in aluminum-magnesium alloys of high magnesium content to result from deformation processing to an initially non recrystallized condition. Analysis here of those data has demonstrated that such a result may be understood in terms of constitutive equations developed for fine-grained materials and that the constitutive equations are applicable to materials achieving grain boundary misorientations in the range of only 2 to 7 by a process of continuous recrystallization. The constitutive equations provide a basis for analysis of anomalous temperature dependence of the strength and of the activation energy for plastic deformation seen as well in this work. A study of the separate effects of processing variables has lead to a model for continuous recrystallization during deformation processing. This model considers recovery of dislocations to sub-boundaries to be the critical step in this process. Application of this model to development of advanced aluminum alloys for air frame structural applications will result in increased weight savings by such processing methods. Theses Keywords: Superplasticity; Aluminum magnesium alloys; Thermomechanical processing; Microstructural evolution; Continuous recrystallization; Microstructural instability; Grain growth.
Download or read book Superplasticity of Ultra Fine Grained Aluminium Alloys written by and published by . This book was released on 1997 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Superplasticity requires a fine grain size, typically in the range of 1 - 10 microns. Experiments have established that much finer grain sizes, in the near-nanometer range, may be achieved in Al-based alloys by using an intense plastic straining technique such as equal-channel angular (ECA) pressing. This report presents the microstructural characteristics and mechanical properties of several ultrafine-grained Al-based alloys processed by ECA pressing. The first demonstration of enhanced superplasticity at low temperatures and high strain rates revealed in commercial Al-alloys, having ultrafine-grained structure, are described.
Download or read book Fundamentals of Creep in Metals and Alloys written by Michael E. Kassner and published by Elsevier. This book was released on 2004-04-06 with total page 289 pages. Available in PDF, EPUB and Kindle. Book excerpt: * Numerous line drawings with consistent format and units allow easy comparison of the behavior of a very wide range of materials * Transmission electron micrographs provide a direct insight in the basic microstructure of metals deforming at high temperatures * Extensive literature review of over 1000 references provide an excellent reference document, and a very balanced discussionUnderstanding the strength of materials at a range of temperatures is critically important to a huge number of researchers and practitioners from a wide range of fields and industry sectors including metallurgists, industrial designers, aerospace R&D personnel, and structural engineers. The most up-to date and comprehensive book in the field, Fundamentals of Creep in Metals and Alloys discusses the fundamentals of time-dependent plasticity or creep plasticity in metals, alloys and metallic compounds. This is the first book of its kind that provides broad coverage of a range of materials not just a sub-group such as metallic compounds, superalloys or crystals. As such it presents the most balanced view of creep for all materials scientists. The theory of all of these phenomena are extensively reviewed and analysed in view of an extensive bibliography that includes the most recent publications in the field. All sections of the book have undergone extensive peer review and therefore the reader can be sure they have access to the most up-to-date research, fully interrogated, from the world's leading investigators.· Numerous line drawings with consistent format and units allow easy comparison of the behavior of a very wide range of materials· Transmission electron micrographs provide a direct insight in the basic microstructure of metals deforming at high temperatures· Extensive literature review of over 1000 references provide an excellent reference document, and a very balanced discussion
Download or read book Superplasticity at High Strain Rates in Aluminum Alloys written by and published by . This book was released on 1996 with total page 16 pages. Available in PDF, EPUB and Kindle. Book excerpt: The detailed experimental data of microstructural developments during the optimum thermomechanical treatments and superplastic properties in the wide deformation range have been investigated on fourteen P/M aluminum alloys with various chemical matrix compositions and different typed precipitate particles. It was revealed that the differences in both size and volume among the second phase particles, which increase with content of Zr, Cr, Mn or Y, affect on the recrystallization behavior, grain size and superplastic properties of these aluminum alloys. Some of them exhibited high-strain-rate superplasticity, so the optimizing processing methods in this proposal were very powerful to provide the desired structures required for high-strain-rate superplasticity in these aluminum alloys. A theoretical interpretation, based on the experimental data by tensile test and the observed grain sizes, has been revealed that values in activation energy for all alloysare between 140 and 155 kJmol-1, which are similar to that for lattice self-diffusion of aluminum. Each mechanical data of each alloy can be presented by a single equation. It was postulated that superplastic flow in these P/M aluminum alloys was fundamentally controlled by a grain boundary sliding mechanism accommodated by dislocation climb controlled by lattice self-diffusion. However, for the statically recrystallized alloys consisted of the high-angle grain boundaries, the Dorn typed equation presents n=2, p=2 and D=D sub L, whereas for the dynamically recrystallized alloys with the low-angle grain boundaries, n=3, p=2 and D=D sub L. The consideration for deformation mechanisms with the accommodation helper by such a liquid has been applied on the aluminum alloys, but it remained unclear.
Download or read book Grain Size Control and Superplasticity in 6013 type Aluminum Alloys written by Lillianne Plaster Whitelock Troeger and published by . This book was released on 1998 with total page 262 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Superplasticity and Grain Boundaries in Ultrafine Grained Materials written by Peter M. Burgess and published by Elsevier. This book was released on 2011-05-31 with total page 327 pages. Available in PDF, EPUB and Kindle. Book excerpt: Superplasticity is a state in which solid crystalline materials, such as some fine-grained metals, are deformed well beyond their usual breaking point. The phenomenon is of importance in processes such as superplastic forming which allows the manufacture of complex, high-quality components in such areas as aerospace and biomedical engineering.Superplasticity and grain boundaries in ultrafine-grained materials discusses a number of problems associated with grain boundaries in metallic polycrystalline materials. The role of grain boundaries in processes such as grain boundary diffusion, relaxation and grain growth is investigated. The authors explore the formation and evolution of the microstructure, texture and ensembles of grain boundaries in materials produced by severe plastic deformation.Written by two leading experts in the field, Superplasticity and grain boundaries in ultrafine-grained materials significantly advances our understanding of this important phenomenon and will be an important reference work for metallurgists and those involved in superplastic forming processes. - Discusses significant problems associated with grain boundaries in polycrystals incorporating structural superplasticity and grain boundary sliding - Assesses the role of grain boundaries in processes such as grain boundary diffusion, relaxation and grain growth - Explores the formation and evolution of the microstructure, texture and ensembles of grain boundaries in materials produced by severe plastic deformation
Download or read book Superplasticity in Metals and Ceramics written by T. G. Nieh and published by Cambridge University Press. This book was released on 1997-01-23 with total page 288 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book describes advances in the field of superplasticity, the ability of certain materials to undergo very large tensile strains. This phenomenon has increasing commercial applications, but also presents a fascinating scientific challenge in attempts to understand the physical mechanisms that underpin it. The authors emphasize the materials aspects of superplasticity. Beginning with a brief history of the phenomenon, they describe the two major types of superplasticity-- fine-structure and internal-stress superplasticity-- and discuss their operative mechanisms. They also present microstructural factors controlling the ductility and fracture in superplastic materials. Observations of superplasticity in metals (including aluminum, magnesium, iron, titanium and nickel), ceramics (including monoliths and composites), intermetallics (including iron, nickel, and titanium base), and laminates are thoroughly described. This is a valuable text for graduate students and researchers in materials science and engineering.
Download or read book Superplasticity in Metals and Ceramics written by T. G. Nieh and published by Cambridge University Press. This book was released on 1997-01-23 with total page 289 pages. Available in PDF, EPUB and Kindle. Book excerpt: A materials engineering monograph in the Cambridge Solid State Science Series, first published in 1997.
Download or read book Aluminium Alloys and Composites written by Kavian Cooke and published by BoD – Books on Demand. This book was released on 2020-03-04 with total page 184 pages. Available in PDF, EPUB and Kindle. Book excerpt: Aluminium (Al) is a metal of great importance because of its excellent corrosion resistance, high electrical and thermal conductivity, good reflectivity, and very good recycling characteristics. The properties of heat-treatable Al-alloys can be further enhanced by the inclusion of a reinforcing phase that increases the mechanical properties of the overall composite. This book is a comprehensive guide on the different types of aluminum alloys and the new advances that have been made in developing and manufacturing aluminum alloys and composites. This text provides a comprehensive overview of the processing, formability, and chemical composition of aluminum alloys and composites. Part One is focused on evaluating the types and properties of advanced aluminum alloys and composites, while Part Two explores characterization. The advantage of this book is that it provides a detailed review of major advances that have occurred in the development and application of aluminum alloys and composites while outlining a development strategy for these materials.
