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Instabilite Plastique Propagative Liee Au Phenomene Portevin Le Chatelier Dans Les Alliages Aluminium Magnesium
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Book Synopsis Instabilité plastique propagative liée au phénomène Portevin-Le Chatelier dans les alliages aluminium-magnésium by : Sabah Bakir
Download or read book Instabilité plastique propagative liée au phénomène Portevin-Le Chatelier dans les alliages aluminium-magnésium written by Sabah Bakir and published by . This book was released on 2016 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Parmi les instabilités plastiques observées dans la déformation des alliages métalliques, le phénomène Portevin-le Chatelier (plc) est le plus couramment rencontre. Ce phénomène résulte d'un mécanisme de vieillissement dynamique du à l'interaction entre les atomes de solutés et les dislocations mobiles. Des effets de dissolution et reprécipitation en cours d'essai peuvent se superposer à ce mécanisme. La conséquence de ces interactions est la baisse de la sensibilité à la vitesse de déformation qui peut devenir négative. Le but du présent travail est l'étude des caractéristiques de l'instabilité plastique plc. Des essais de traction ont été effectues entre -60c et 100c, sur des alliages al-mg sollicites dans une large plage de vitesses de chargement sur deux types de machines: - machine souple ou la vitesse de contrainte est imposée. - machine dure ou la vitesse de déformation est imposée. L'effet plc se traduit par des bandes de déformation qui se propagent à travers l'éprouvette d'essai. Les résultats expérimentaux obtenus dans cette étude concernent essentiellement les vitesses de propagation, les déformations et les vitesses de déformation de ces bandes. L'examen de l'évolution des déformations critiques #c pour l'apparition du plc ou des vitesses de bande fait apparaitre que ces grandeurs passent par une transition dans le domaine des vitesses de sollicitation intermédiaires. La comparaison des résultats expérimentaux avec les approches théoriques qui tentent d'expliquer l'effet plc, montrent que les modèles de vieillissement dynamique rendent compte qualitativement de l'évolution de #c aux vitesses de chargement élevées. Aux faibles vitesses de sollicitation, le comportement inverse de #c résulte de la coexistence du vieillissement dynamique avec les effets de reprécipitation après dissolution. L'ensemble des résultats obtenus dans ce travail permet d'élargir les connaissances actuelles sur le phénomène plc et de mieux appréhender ses effets néfastes sur la formabilité des métaux.
Download or read book Archives of metallurgy written by and published by . This book was released on 1986 with total page 604 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Étude expérimentale de l'effet Portevin-Le Chatelier dans trois alliages aluminium-magnésium dans des conditions de vitesse de déformation ou de contrainte imposées by : Mohammed Dablij
Download or read book Étude expérimentale de l'effet Portevin-Le Chatelier dans trois alliages aluminium-magnésium dans des conditions de vitesse de déformation ou de contrainte imposées written by Mohammed Dablij and published by . This book was released on 1998 with total page 141 pages. Available in PDF, EPUB and Kindle. Book excerpt: L'instabilité de la déformation plastique liée au phénomène Portevin-Le Chatelier (PLC) se manifeste par l'apparition et la propagation de bandes de déformation. L'hétérogénéité de la déformation qui en résulte dégrade la formabilité du matériau et donne un aspect rugueux à la surface après formage. Pour éviter ces effets néfastes, il est nécessaire de bien cerner les facteurs qui conditionnent le déclenchement de ces instabilités. Bien que le phénomene PLC soit connu depuis longtemps, les modélisations et les résultats expérimentaux sont encore fragmentaires et parfois contradictoires. L'objectif du présent travail est la caractérisation de l'instabilité plastique PLC dans trois alliages d'aluminium-magnésium à la température ambiante ; d'une part, en étudiant les caractéristiques des bandes de déformation et les divers aspects de cette instabilité sur les courbes contrainte-déformation ; d'autre part, en mettant en évidence l'influence de la teneur en magnésium et de l'état microstructural initial sur le déclenchement de l'effet PLC. L'étude expérimentale a été menée dans un large intervalle de vitesses de chargement en utilisant deux types de machines de traction : une machine dure ou la vitesse de déformation est imposée, et une machine souple ou la vitesse de contrainte est imposée. L'evolution de la déformation critique à laquelle apparait l'effet PLC avec la vitesse de chargement, présente en général deux branches : une ascendante décrite qualitativement par les modèles basés sur le processus de vieillissement dynamique, et une descendante prévue par les modèles prenant en compte les effets de précipitation dynamique et de cisaillement de précipités. Une saturation au cours de la déformation et une sensibilité négative à la vitesse de déformation des caractéristiques des décrochements sur machine dure ont été observée. Ces résultats sont en accord avec les modèles macroscopiques de l'effet PLC bases sur une sensibilité négative à la vitesse de déformation. L'étude des variations des caractéristiques de bandes PLC, au cours de la déformation et en fonction de la vitesse de chargement, a été effectuée. La diminution de la vitesse de propagation de bande avec la vitesse de chargement concorde qualitativement avec les prévisions de certains modèles théoriques. Nous avons trouvé une similitude entre les évolutions de la déformation et de la vitesse de déformation dans les bandes. Enfin, l'étude comparative entre les trois alliages a montré que la teneur en magnésium et l'état microstructural initial influent de manière significative sur les conditions d'apparition et l'aspect du phénomène PLC. Les résultats obtenus dans le cadre de cette thèse constituent une contribution visant à approfondir la compréhension de l'effet PLC, et à fournir une base de données expérimentales pouvant aider à développer de nouvelles modélisations théoriques.
Book Synopsis Caractérisation de l'effet Portevin Le Chatelier dans les alliages Aluminium Magnésium by : Khaidre Bouabdallah
Download or read book Caractérisation de l'effet Portevin Le Chatelier dans les alliages Aluminium Magnésium written by Khaidre Bouabdallah and published by . This book was released on 2006 with total page 148 pages. Available in PDF, EPUB and Kindle. Book excerpt: Les instabilités mécaniques associées à l'effet Portevin Le Chatelier (PLC) se manifestent par des hétérogénéités macroscopiques sous forme de bandes de localisation de la déformation plastique. Ce phénomène affecte les propriétés mécaniques du matériau et réduit la qualité du produit lors de la fabrication par mise en forme. Nous avons étudié le comportement instable de la déformation plastique dans une série d'alliages d'Aluminium Magnésium dilués industriels largement utilisés pour la fabrication de pièces mécaniques par emboutissage. Pour la caractérisation des instabilités PLC dans ces matériaux, les essais mécaniques ont été réalisés en traction uniaxiale à vitesse de déformation imposée. Les conditions d'apparition et de propagation des bandes de localisation de la déformation plastique liées au phénomène PLC ont été étudiées dans une large gamme de vitesses de déformation à température ambiante. L'influence de la teneur en élément d'alliage (Mg) sur les caractéristiques des instabilités est clairement établie. Nos résultats confirment l'existence d'une sensibilité négative de la contrainte d'écoulement par rapport à la vitesse de déformation dans l'ensemble du domaine de l'effet PLC. Nous montrons que le mode de propagation des bandes PLC dépend non seulement de la vitesse de déformation imposée mais aussi du taux d'écrouissage du matériau. Parallèlement au dispositif d'essai de traction classique nous avons enregistré les variations des champs de déplacement et de température en surface de l'éprouvette au cours de la déformation plastique. L'analyse par corrélation d'images de ces données a permit de mettre en évidence les différents modes de génération et de propagation des bandes A, B et C caractéristiques de l'effet PLC. Les paramètres physiques relatifs aux bandes PLC tels que largeur, vitesse de propagation et de déformation à l'intérieur de la bande ont été quantifiés. Nos investigations montrent, grâce à l'analyse des enregistrements par thermographie infrarouge, que l'instabilité PLC est associée à un saut de température propre à chaque type de bande en même temps qu'une décharge élastique ressentie par l'ensemble de l'éprouvette. En rapport avec le développement actuel dans le domaine de la modélisation du comportement mécanique des matériaux, l'analyse de la déformation plastique instable donne accès à des paramètres indispensables pour la mise au point de simulations par éléments finis réalistes.
Book Synopsis Advanced Light Alloys and Composites by : R. Ciach
Download or read book Advanced Light Alloys and Composites written by R. Ciach and published by Springer Science & Business Media. This book was released on 1998-09-30 with total page 538 pages. Available in PDF, EPUB and Kindle. Book excerpt: An expert exposition of the structural and mechanical properties of light alloys and composites, bridging the gap between scientists and industrial engineers in its consideration of advanced light materials, their structure, properties, technology and application. Includes basic problems of alloy constitution and phase transformations. The aluminium alloys are the main topic of the book, consideration being given to their properties, casting technology, thermomechanical treatment and structure. Attention is also given to the magnesium alloys, particularly those having rare earth metal constituents. Both commercial titanium alloys and intermetallic compounds are discussed, as are metallic composites. The latest engineering techniques are discussed in both theoretical and practical terms.
Book Synopsis Fatigue and Durability of Structural Materials by : Gary R. Halford
Download or read book Fatigue and Durability of Structural Materials written by Gary R. Halford and published by ASM International. This book was released on 2006 with total page 471 pages. Available in PDF, EPUB and Kindle. Book excerpt: Fatigue and Durability of Structural Materials explains how mechanical material behavior relates to the design of structural machine components. The major emphasis is on fatigue and failure behavior using engineering models that have been developed to predict, in advance of service, acceptable fatigue and other durability-related lifetimes. The book covers broad classes of materials used for high-performance structural applications such as aerospace components, automobiles, and power generation systems. Coverage focuses on metallic materials but also addresses unique capabilities of important nonmetals. The concepts are applied to behavior at room or ambient temperatures; a planned second volume will address behavior at higher-temperatures. The volume is a repository of the most significant contributions by the authors to the art and science of material and structural durability over the past half century. During their careers, including 40 years of direct collaboration, they have developed a host of durability models that are based on sound physical and engineering principles. Yet, the models and interpretation of behavior have a unique simplicity that is appreciated by the practicing engineer as well as the beginning student. In addition to their own pioneering work, the authors also present the work of numerous others who have provided useful results that have moved progress in these fields. This book will be of immense value to practicing mechanical and materials engineers and designers charged with producing structural components with adequate durability. The coverage is appropriate for a range of technical levels from undergraduate engineering students through material behavior researchers and model developers. It will be of interest to personnel in the automotive and off-highway vehicle manufacturing industry, the aeronautical industry, space propulsion and the power generation/conversion industry, the electric power industry, the machine tool industry, and any industry associated with the design and manufacturing of mechanical equipment subject to cyclic loads.
Book Synopsis Deformation Kinetics by : A. S. Krausz
Download or read book Deformation Kinetics written by A. S. Krausz and published by Wiley-Interscience. This book was released on 1975 with total page 426 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Fracture Kinetics of Crack Growth by : A.S. Krausz
Download or read book Fracture Kinetics of Crack Growth written by A.S. Krausz and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 189 pages. Available in PDF, EPUB and Kindle. Book excerpt: Over the past few years, we have made numerous presentations, delivered several series of lectures, and participated in many discussions on the processes of time-dependent crack growth. We felt that the understanding of these processes had reached a degree of maturity: the basic physical principles were established and their application to engineering practice was now feasible. We concluded that the best way to organize this knowledge was to write it up in a single, coherent system. Martinus Nijhoff kindly encouraged us and generously offered their collaboration. Hence, this book. The physical process of time-dependent subcritical crack growth is rigorously defined by statistical mechanics. If well presented, the principles can be readily understood by practitioners of fracture research and design engineers. We present the physical processes of crack growth in terms of atomic interactions that assume only a working knowledge of the standard engineering materials course contents. From this, we develop a framework that is valid for any type of material, be it metallic, polymeric, ceramic, glass or mineral - indeed, any solid. We also assume an elementary exposure to fracture mechanics. An appendix is provided that outlines those aspects of fracture mechanics that are needed for an introduction to fracture kinetics analyses; it also provides a common ground for concepts and terminology (see Appendix A). We proceed through theory to applications that are of interest in research, development and design, as well as in test and operating engineering practice.
Book Synopsis Age-hardenable Aluminium Alloys by : István Kovács
Download or read book Age-hardenable Aluminium Alloys written by István Kovács and published by . This book was released on 1987 with total page 652 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book presents more than 60 papers on various topics of current interest, concerning the development of new types of alloys, trace elements, analytical techniques, the physics of the decomposition process, dislocation structure and technological applications.
Book Synopsis Phase Diagrams of Binary Titanium Alloys by : Joanne L. Murray
Download or read book Phase Diagrams of Binary Titanium Alloys written by Joanne L. Murray and published by . This book was released on 1987 with total page 368 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis The Science, Technology and Application of Titanium by : R. I. Jaffee
Download or read book The Science, Technology and Application of Titanium written by R. I. Jaffee and published by Elsevier. This book was released on 2013-09-24 with total page 1225 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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.
Book Synopsis High-Temperature Ordered Intermetallic Alloys IV: Volume 213 by : L. A. Johnson
Download or read book High-Temperature Ordered Intermetallic Alloys IV: Volume 213 written by L. A. Johnson and published by Materials Research Society. This book was released on 1991-05-31 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: The MRS Symposium Proceeding series is an internationally recognised reference suitable for researchers and practitioners.
Book Synopsis L'Esprit de L'Escalier by : Dominique / D. Bonten /
Download or read book L'Esprit de L'Escalier written by Dominique / D. Bonten / and published by CreateSpace. This book was released on 2014-01 with total page 140 pages. Available in PDF, EPUB and Kindle. Book excerpt: L'esprit de L'escalier is a French term for when you think of what you should have said after it is too late. This is a collection of poetry; These are things you wish you said.
Book Synopsis Multi-functional Materials and Structures by : Alan Kin Tak Lau
Download or read book Multi-functional Materials and Structures written by Alan Kin Tak Lau and published by Trans Tech Publications Ltd. This book was released on 2008-06-12 with total page 1612 pages. Available in PDF, EPUB and Kindle. Book excerpt: Volume is indexed by Thomson Reuters CPCI-S (WoS). Smart Materials are materials that can respond to environmental stimuli by exhibiting particular changes in some of their properties. Depending upon the change in some external condition, a smart materials can change its own characteristics (mechanical, electrical, appearance), structure, composition and/or response. These materials are usually embedded into systems whose inherent properties change favourably in order to meet performance needs.
Book Synopsis The Evolution of Technology by : George Basalla
Download or read book The Evolution of Technology written by George Basalla and published by Cambridge University Press. This book was released on 1989-02-24 with total page 262 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book presents an evolutionary theory of technological change based upon recent scholarship in the history of technology and upon relevant material drawn from economic history and anthropology. It challenges the popular notion that technology advances by the efforts of a few heroic individuals who produce a series of revolutionary inventions owing little or nothing to the technological past. Therefore, the book's argument is shaped by analogies taken selectively from the theory of organic evolution, and not from the theory and practice of political revolution. Three themes appear, and reappear with variations, throughout the study. The first is diversity: an acknowledgment of the vast numbers of different kinds of made things (artifacts) that have long been available to humanity; the second is necessity: the belief that humans are driven to invent new artifacts in order to meet basic biological requirements such as food, shelter, and defense; and the third is technological evolution: an organic analogy that explains both the emergence of novel artifacts and their subsequent selection by society for incorporation into its material life without invoking either biological necessity or technological progress. Although the book is not intended to provide a strict chronological account of the development of technology, historical examples - including many of the major achievements of Western technology: the waterwheel, the printing press, the steam engine, automobiles and trucks, and the transistor - are used extensively to support its theoretical framework. The Evolution of Techology will be of interest to all readers seeking to learn how and why technology changes, including both students and specialists in the history of technology and science.
Book Synopsis Magnesium Alloys Containing Rare Earth Metals by : L.L. Rokhlin
Download or read book Magnesium Alloys Containing Rare Earth Metals written by L.L. Rokhlin and published by CRC Press. This book was released on 2003-02-20 with total page 256 pages. Available in PDF, EPUB and Kindle. Book excerpt: Magnesium-based alloys containing rare-earth metals are important structural materials, as they combine low density with high-strength properties. This makes them particularly attractive for industry, especially in cases where the low weight of constructions is critical, as in aircraft and space apparatus construction. One of the remarkable feature
Book Synopsis Technology in Western Civilization: Technology in the twentieth century by : Melvin Kranzberg
Download or read book Technology in Western Civilization: Technology in the twentieth century written by Melvin Kranzberg and published by Oxford University Press, USA. This book was released on 1967 with total page 792 pages. Available in PDF, EPUB and Kindle. Book excerpt: A complete and well-planned account of the history of technology in Western civilization from pre-historic man to the present age of the computer.
