DOCSLIB.ORG

An Investigation of Hot Forming Quench Process for Aa6082 Aluminium Alloys

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
An Investigation of Hot Forming Quench Process for Aa6082 Aluminium Alloys IMPERIAL COLLEGE LONDON AN INVESTIGATION OF HOT FORMING QUENCH PROCESS FOR AA6082 ALUMINIUM ALLOYS A thesis submitted to Imperial College London for the degree of Doctor of Philosophy By MOHAMED SAAD KAMEL MOHAMED Department of Mechanical Engineering Imperial College London London SW7 2AZ 2010 Synopsis Synopsis This thesis is concerned with the mechanical properties and microstructure evolution during the novel solution Heat treatment Forming cold die Quenching (HFQ) process. HFQ is a hot sheet forming technology which incorporates the forming and quenching stages to produce high strength and high precision Al-alloy sheet parts. The work in the thesis divided into three main sections: Firstly, viscoplastic behaviour of AA6082 at different deformation temperatures and strain rates was identified through analysis of a programme of hot tensile tests. Based on the results from the hot tensile tests, a set of unified viscoplastic-damage constitutive equations was developed and determined for AA6082, providing a good agreement with the experimental results. SEM tests were carried out to investigate the damage nucleation and failure features of the AA6082 during hot forming process and the results are discussed. Secondly, the viscoplastic-damage constitutive equations were implemented into the commercial software ABAQUS via the user defined subroutine VUMAT for the forming process simulation. An experimental programme was designed and testing facilities were established for the validation of the FE process modelling results. A fairly good agreement between the process simulation and the experimental results was achieved. This confirms that the established FE process simulation model can be used for hot stamping of AA6082 panel parts. Further process modelling work was carried out to identify the optimal forming parameters for a simplified representation of a panel part. Finally, a precipitation hardening model was developed to predict the post-ageing strength of AA6082 panel parts, having varying amounts of forming-induced plastic strain. The model was tested against results of experiments which were carried out to 1 Synopsis investigate the effect of pre-deformation on the ageing kinetics of AA6082. The model is shown to fit and can be used to explain changes in the strength of the material. This set of equations was implemented in the VUMAT, in combination with the viscoplastic damage constitutive equation set, to model the whole HFQ process. The FE model was tested with experimental ageing and hardness results providing good agreements, which are discussed in light of the future development of the HFQ process. 2 Acknowledgements Acknowledgements I would like to express my gratitude to my supervisor Prof. Jianguo Lin for supervising my research and for his constant interest throughout the work and superb guidance and endless patience. His guidance, encouragement, and assistance have been a great help and I am indebted to him for providing the opportunity for me to develop the research presented in this dissertation. I wish to express my gratitude to Dr. Alistair Foster; he has always been available for suggestion and advice during several steps of the research. I thank also my colleagues in my office for their support, advice, and encouragement. I would like to express my thanking to my country Egypt for providing a scholarship for my PHD studies. A heartfelt thank to my wife, my daughter and my mother for their patience and support throughout my study in UK. 3 Table of Contents Table of Contents Synopsis ............................................................................................................................ 1 Acknowledgements .......................................................................................................... 3 Table of Contents ............................................................................................................. 4 List of Figures................................................................................................................... 9 List of Tables .................................................................................................................. 14 Nomenclature ................................................................................................................. 15 Chapter 1 Introduction .................................................................................................... 18 1.1 Automotive lightweight requirements .................................................................. 18 1.2 Forming of aluminium alloy panel components ................................................... 25 1.3 Introduction to the HFQ process ........................................................................... 28 1.4 Aims and structure of the thesis ............................................................................ 31 Chapter 2 Advanced Forming Techniques ..................................................................... 34 2.1 Introduction ........................................................................................................... 34 2.2 Manufacturing of lightweight components by metal forming .............................. 34 2.3 Advanced techniques for achieving high formability of materials ....................... 38 2.3.1 Superplastic forming (SPF) of sheet metal components ................................ 39 2.3.2 Hydroforming Process ................................................................................... 41 2.4 Development of hot stamping and cold die quenching processes ........................ 43 2.5 Microstructure control .......................................................................................... 46 2.6 Discussion and summary ...................................................................................... 50 Chapter 3 Experimental Programme .............................................................................. 52 3.1 Introduction and objectives ................................................................................... 52 3.2 Test material ......................................................................................................... 53 4 Table of Contents 3.3 Experimental programme of thermal and hardness tests for quenching rate effect .................................................................................................................................... 54 3.3.1 Sample preparation ......................................................................................... 55 3.3.2 Test facilities .................................................................................................. 56 3.3.2.1 Gleeble material simulator ...................................................................... 56 3.3.3 Test procedures .............................................................................................. 57 3.4 Experimental programme for ductility tests (hot tensile tests) ............................. 58 3.4.1 Test procedures .............................................................................................. 58 3.5 Strain ageing test for AA6082 .............................................................................. 60 3.5.1 Test procedures .............................................................................................. 60 3.6 Experimental programme for formability tests ..................................................... 61 3.6.1 Sample preparation ......................................................................................... 62 3.6.2 Test facilities .................................................................................................. 63 3.6.2.1 Hydraulic press and formability die sets ................................................. 63 3.6.3 Test procedures .............................................................................................. 65 Chapter 4 Experimental Results and discussions ........................................................... 67 4.1 Introduction ........................................................................................................... 67 4.2 Effect of the quenching rate on the mechanical properties of AA6082 alloys ..... 67 4.3 Effect of the high temperature deformation regime on the mechanical properties for AA6082 ................................................................................................................. 70 4.3.1 The effect of strain rate on the mechanical properties of AA6082 ................ 70 4.3.2 The effect of deformation temperature on the mechanical properties of AA6082 ................................................................................................................... 71 4.4 The effect of plastic deformation on the ageing kinetics prior to artificial ageing for AA6082 alloys ...................................................................................................... 73 5 Table of Contents 4.5 The effect of forming rate and drawing depth on the failure features and formability for AA6082 alloys ................................................................................... 74 4.6 Conclusions from the experimental results ........................................................... 76 Chapter 5 Development of Viscoplastic Damage Constitutive Equations ..................... 81 5.1 Introduction ........................................................................................................... 81 5.2 Deformation and damage mechanisms
Load more

Recommended publications
  • The Use of Titanium in Dentistry
    Cells and Materials Volume 5 Number 2 Article 9 1995 The Use of Titanium in Dentistry Toru Okabe Baylor College of Dentistry, Dallas Hakon Hero Scandinavian Institute of Dental Materials, Haslum Follow this and additional works at: https://digitalcommons.usu.edu/cellsandmaterials Part of the Dentistry Commons Recommended Citation Okabe, Toru and Hero, Hakon (1995) "The Use of Titanium in Dentistry," Cells and Materials: Vol. 5 : No. 2 , Article 9. Available at: https://digitalcommons.usu.edu/cellsandmaterials/vol5/iss2/9 This Article is brought to you for free and open access by the Western Dairy Center at DigitalCommons@USU. It has been accepted for inclusion in Cells and Materials by an authorized administrator of DigitalCommons@USU. For more information, please contact [email protected]. Cells and Materials, Vol. 5, No. 2, 1995 (Pages 211-230) 1051-6794/95$5 0 00 + 0 25 Scanning Microscopy International, Chicago (AMF O'Hare), IL 60666 USA THE USE OF TITANIUM IN DENTISTRY Toru Okabe• and HAkon Hem1 Baylor College of Dentistry, Dallas, TX, USA 1Scandinavian Institute of Dental Materials (NIOM), Haslum, Norway (Received for publication August 8, 1994 and in revised form September 6, 1995) Abstract Introduction The aerospace, energy, and chemical industries have Compared to the metals and alloys commonly used benefitted from favorable applications of titanium and for many years for various industrial applications, tita­ titanium alloys since the 1950's. Only about 15 years nium is a rather "new" metal. Before the success of the ago, researchers began investigating titanium as a mate­ Kroll process in 1938, no commercially feasible way to rial with the potential for various uses in the dental field, produce pure titanium had been found.
    [Show full text]
  • Superplastic Forming, Electromagnetic Forming, Age Forming, Warm Forming, and Hydroforming
    ANL-07/31 Innovative Forming and Fabrication Technologies: New Opportunities Final Report Energy Systems Division About Argonne National Laboratory Argonne is a U.S. Department of Energy laboratory managed by UChicago Argonne, LLC under contract DE-AC02-06CH11357. The Laboratory’s main facility is outside Chicago, at 9700 South Cass Avenue, Argonne, Illinois 60439. For information about Argonne, see www.anl.gov. Availability of This Report This report is available, at no cost, at http://www.osti.gov/bridge. It is also available on paper to the U.S. Department of Energy and its contractors, for a processing fee, from: U.S. Department of Energy Office of Scientific and Technical Information P.O. Box 62 Oak Ridge, TN 37831-0062 phone (865) 576-8401 fax (865) 576-5728 [email protected] Disclaimer This report was prepared as an account of work sponsored by an agency of the United States Government. Neither the United States Government nor any agency thereof, nor UChicago Argonne, LLC, nor any of their employees or officers, makes any warranty, express or implied, or assumes any legal liability or responsibility for the accuracy, completeness, or usefulness of any information, apparatus, product, or process disclosed, or represents that its use would not infringe privately owned rights. Reference herein to any specific commercial product, process, or service by trade name, trademark, manufacturer, or otherwise, does not necessarily constitute or imply its endorsement, recommendation, or favoring by the United States Government or any agency thereof. The views and opinions of document authors expressed herein do not necessarily state or reflect those of the United States Government or any agency thereof, Argonne National Laboratory, or UChicago Argonne, LLC.
    [Show full text]
  • Pulse Pressure Forming of Lightweight Materials, Development
    2010 DOE Vehicle Technologies Program Review Presentation LM015, Mark T. Smith, (509) 375-4478, [email protected] 1. Pulse Pressure Forming of Lightweight Materials 2. Development of High Strength Superplastic Aluminum Sheet for Automotive Applications 3. Friction Stir Spot Welding of Advanced High Strength Steels This presentation does not contain proprietary, confidential, or otherwise restricted information Project ID: LM015 1 (Project 18987/Agreement 17239) 2010 DOE Vehicle Technologies Program Review Pulse Pressure Forming of Lightweight Materials P.I.: Richard Davies, (509) 375-6474, [email protected] Presenter: Mark T. Smith, (509) 375-4478, [email protected] This presentation does not contain proprietary, confidential, or otherwise restricted information Project ID: LM015 2 Project Overview Project Timeline: Targets Start – 3Q FY08 The VTP target for weight reduction of the vehicle and its Finish – 3Q FY11 subsystems is 50%. 65% complete Pulse Pressure Forming (PPF) of aluminum and Advanced High Strength Steels (AHSS) has the potential to achieve 25 to 45% weight savings vs. Budget: conventional steels Total project funding: Barriers PNNL: $1475k Barriers to using PPF of aluminum and AHSS in the lightweighting of vehicles: FY08 Funding Received: Lack of understanding of the formability and strain rates that develop during PPF processing $200k Lack of validated constitutive relations for lightweight materials during PPF processing FY09 Funding Received: Lack of validation of finite element simulation of $450k PPF processing Partners FY10 Funding Received: OEM and Industry participants: $450k Sergey Golovashchenko (Ford) John Bradley (General Motors) FY11 Funding Request: Ajit Desai, Chrysler $375k US Steel, Alcoa Relevance to Technology Gaps: Project Objectives: Enable broader deployment of automotive lightweighting materials in body-in-white and closure panels through extended formability of aluminum alloys, magnesium alloys, and HSS/AHSS.
    [Show full text]
  • Table of Contents
    THERMEC 2018 ISBN(softcover): 978-3-0357-1208-7 ISBN(eBook): 978-3-0357-3208-5 Table of Contents Preface Chapter 1: Steels. Properties and Processing Technologies Effect of Mo, Nb and V on Hot Deformation Behaviour, Microstructure and Hardness of Microalloyed Steels N. Singh, A.G. Kostryzhev, C.R. Killmore and E.V. Pereloma 3 Extended Application of Hardness Prediction System for Temper Bead Welding of A533B Steel to Various Low-Alloy Steels L.N. Yu, K. Saida and K. Nishimoto 9 Cracking and Failure in a High Strength Low Alloy Steel during Solidification A. Loucif, D. Shahriari, K. Chadha, C.P. Zhang, M. Jahazi, R. Tremblay and L.P. Lapierre-Boire 15 Effect of Annealing Conditions on the Dissolution Process of Complex Carbonitrides in a V- Nb-Ti Microalloyed Steel G. Basanta, A.L. Rivas, E. Díaz and C. Parra 21 The Effect of Test Temperature on Deformation Microstructure and Fracture Mechanisms in CrMn High-Nitrogen Steels Alloyed (0-3 wt.%) with Vanadium E. Astafurova, V. Moskvina, G.G. Maier, E. Melnikov, N. Galchenko, S. Astafurov, A. Gordienko, A. Burlachenko, A. Smirnov and V. Bataev 27 Characterisation of Precipitation and Coarsening of Carbides during Tempering in a Low Alloyed Quenched and Tempered Steel Y.L. Ju, A. Goodall, C. Davis and M. Strangwood 33 On the Microstructural Characteristics of UFG Microalloyed Steel Influencing the Mechanical Behavior under Dynamic Loading J. Majta, R. Bloniarz, M. Kwiecień and K. Muszka 39 Critical Strain for Complete Austenite Recrystallisation during Rough Rolling of C-Mn Steel and Nb-Ti-V Microalloyed Steel D.R.N.
    [Show full text]
  • Contents/ 2/6/2008 10:04AM Plate # 0 Pg Iii
    Name ///sr-nova/Dclabs_wip/Metallurgy/5224_iii-xii.pdf/Front Matter_Contents/ 2/6/2008 10:04AM Plate # 0 pg iii © 2008 ASM International. All Rights Reserved. Elements of Metallurgy and Engineering Alloys (#05224G) www.asminternational.org Contents Preface ........................................................................................................................... xiii Part I: Physical and Mechanical Metallurgy ....................................................................... 1 Chapter 1 Metallic Structure .......................................................................................... 3 1.1 Periodic Table ......................................................................................................................... 3 1.2 Bonding in Solids ................................................................................................................... 4 1.2.1 Metallic Bonding ............................................................................................................. 5 1.2.2 Ionic Bonding .................................................................................................................. 7 1.2.3 Covalent Bonding ............................................................................................................7 1.2.4 Secondary Bonding ......................................................................................................... 8 1.3 Crystalline Structure ..............................................................................................................
    [Show full text]
  • Research and Development of Superplastic Materials -Recent Progresses and Future Prospects -* by Masaru KOBAYASHI** and Matsuo M
    Research and Development of Superplastic Materials -Recent Progresses and Future Prospects -* By Masaru KOBAYASHI** and Matsuo MIYAGAWA** Key words: superplasticity; grain refinement; superplastic forming; that are based on eutectic or eutectoid compositions. internal cavity. These materials are characterized by the microduplex equiaxed grain structure with dispersion of a second I. Introduction phase sufficiently to inhibit grain coarsening during Superplasticity, as a generally accepted metallurgi- deformation. Findings of these microstructural char- cal concept, is the phenomenon of enhanced ductility acteristics lead to the developments of a variety of under a low resistance to deformation, associated with nonferrous alloys with the base of Ag, Al, Bi, Cd, Go, the microstructural behavior such as slip, twinning, Cr, Cu, Mg, Pb, Sn, and Zn. grain boundary migration, phase transformation, pre- Progresses in grain refinement techniques have pro- cipitation, and recrystallization. vided the various methods of synthesizing materials There are now a large number of investigations on for attaining superplastic properties. Rapidly solidi- the mechanisms and contributing factors of unusually fled powders and films have been found to prepare high tensile elongation. Industrial applications of superplastic alloys with fine but non-equiaxed grain superplasticity have recently been developed for plas- structures. A variety of alloys have been shown to be tic forming. Other applications as the functional rendered superplastic : These materials include
    [Show full text]
  • Ancient and Modern Laminated Composites — from the Great Pyramid of Gizeh to Y2K
    Preprint UCRL-JC-135031 Ancient and Modern Laminated Composites — From the Great Pyramid of Gizeh to Y2K J. Wadsworth and D. R. Lesuer This article was submitted to International Metallographic Society 1999 Conference, Cincinnati, OH, October 21 – November 3, 1999 March 14, 2000 Approved for public release; further dissemination unlimited DISCLAIMER This document was prepared as an account of work sponsored by an agency of the United States Government. Neither the United States Government nor the University of California nor any of their employees, makes any warranty, express or implied, or assumes any legal liability or responsibility for the accuracy, completeness, or usefulness of any information, apparatus, product, or process disclosed, or represents that its use would not infringe privately owned rights. Reference herein to any specific commercial product, process, or service by trade name, trademark, manufacturer, or otherwise, does not necessarily constitute or imply its endorsement, recommendation, or favoring by the United States Government or the University of California. The views and opinions of authors expressed herein do not necessarily state or reflect those of the United States Government or the University of California, and shall not be used for advertising or product endorsement purposes. This is a preprint of a paper intended for publication in a journal or proceedings. Since changes may be made before publication, this preprint is made available with the understanding that it will not be cited or reproduced without the permission of the author. This report has been reproduced directly from the best available copy. Available to DOE and DOE contractors from the Office of Scientific and Technical Information P.O.
    [Show full text]
  • FY 2005 Progress Report for High Strength Weight Reduction Materials
    Annual Progress Report HIGH STRENGTH WEIGHt REDUCTION MATERIALS Less dependence on foreign oil, and eventual transition to an emissions-free, petroleum-free vehicle A Strong Energy Portfolio for a Strong America F R E E D O M C A R A N D V E H I C L E T E C H N O L O G I E S P R O G R A M Energy efficiency and clean, enewabler energy will mean a stronger economy, a cleaner environment, and greater energy independence for America. Working with a wide array of state, community, industry, and university partners, the U.S. Department of Energy’s Office of Energy Efficiency and Renewable Energy invests in a diverse portfolio of energy technologies. For more information contact: EERE Information Center 1-877-EERE-INF (1-877-337-3463) www.eere.energy.gov Acknowledgement We would like to express our sincere appreciation to QSS Group, Inc., Oak Ridge National Laboratory, and Argonne National Laboratory for their technical and artistic contributions in preparing and publishing this report. In addition, we would like to thank all the participants for their contributions to the pro­ grams and all the authors who prepared the project abstracts that comprise this report. This document highlights work sponsored by agencies of the U.S. Government. Neither the U.S. Government nor any agency thereof, nor any of their employees, makes any warranty, express or implied, or assumes any legal liability or responsibility for the accuracy, completeness, or usefulness of any information, apparatus, product, or process disclosed, or represents that its use would not infringe privately owned rights.
    [Show full text]
  • Industrial Metallurgy Department of Metallurgical and Materials Engineering
    M.Tech – Industrial Metallurgy Department of Metallurgical and Materials Engineering M.Tech. Degree in INDUSTRIAL METALLURGY SYLLABUS FOR CREDIT BASED CURRICULUM (For the students admitted in the year 2016) DEPARTMENT OF METALLURGICAL AND MATERIALS ENGINEERING NATIONAL INSTITUTE OF TECHNOLOGY TIRUCHIRAPPALLI - 620 015 TAMIL NADU, INDIA 1 M.Tech – Industrial Metallurgy Department of Metallurgical and Materials Engineering Programme Educational Objectives (PEO) of M.Tech. (Industrial Metallurgy) I.choose their careers as practicing metallurgist in manufacturing and service industries. II.To pursue research in the areas of metallurgical engineering III. To work and participate in multidisciplinary environments as well as to develop entrepreneur skills Programme Outcomes (PO) 1 The industrial metallurgy graduates are capable of applying knowledge of basic sciences, mathematics and engineering in their fields. 2 The industrial metallurgy graduates are capable of testing and conduct experiments related to their work as well as to analyze and interpret the results 3 The industrial metallurgy graduates are capable of doing design and development of processes or system keeping in view of socio-economic aspects. 4 The industrial metallurgy graduates are capable of involving and work together in a team. 5 The industrial metallurgy graduates are able to apply their knowledge and skills in solving industrial problems effectively 6 The industrial metallurgy graduates are capable to utilize the recent cutting edge technologies, innovative practices to
    [Show full text]
  • Integrated Approach to the Superplastic Forming of Magnesium Alloys
    University of Kentucky UKnowledge University of Kentucky Doctoral Dissertations Graduate School 2007 INTEGRATED APPROACH TO THE SUPERPLASTIC FORMING OF MAGNESIUM ALLOYS Fadi K. Abu-Farha University of Kentucky, [email protected] Right click to open a feedback form in a new tab to let us know how this document benefits ou.y Recommended Citation Abu-Farha, Fadi K., "INTEGRATED APPROACH TO THE SUPERPLASTIC FORMING OF MAGNESIUM ALLOYS" (2007). University of Kentucky Doctoral Dissertations. 493. https://uknowledge.uky.edu/gradschool_diss/493 This Dissertation is brought to you for free and open access by the Graduate School at UKnowledge. It has been accepted for inclusion in University of Kentucky Doctoral Dissertations by an authorized administrator of UKnowledge. For more information, please contact [email protected]. ABSTRACT OF DISSERTATION Fadi K. Abu-Farha The Graduate School University of Kentucky 2007 1 INTEGRATED APPROACH TO THE SUPERPLASTIC FORMING OF MAGNESIUM ALLOYS ABSTRACT OF DISSERTATION A dissertation submitted in partial fulfilment of the requirements for the degree of Doctor of Philosophy in the College of Engineering at the University of Kentucky By Fadi K. Abu-Farha Director: Dr. Marwan K. Khraisheh, Professor of Mechanical Engineering 2007 Copyright © Fadi K. Abu-Farha 2007 2 ABSTRACT OF DISSERTATION INTEGRATED APPROACH TO THE SUPERPLASTIC FORMING OF MAGNESIUM ALLOYS The economical and environmental issues associated with fossil fuels have been urging the automotive industry to cut the fuel consumption and exhaust emission levels, mainly by reducing the weight of vehicles. However, customers’ increasing demands for safer, more powerful and luxurious vehicles have been adding more weight to the various categories of vehicles, even the smallest ones.
    [Show full text]
  • Boronization and Carburization of Superplastic Stainless Steel and Titanium-Based Alloys
    Materials 2011, 4, 1309-1320; doi:10.3390/ma4071309 OPEN ACCESS materials ISSN 1996-1944 www.mdpi.com/journal/materials Review Boronization and Carburization of Superplastic Stainless Steel and Titanium-Based Alloys Masafumi Matsushita Department of Mechanical Engineering, Ehime University, 3-Bunkyocho, Matsuyama 790-8577, Japan; E-Mail: [email protected]; Tel.: +81-89-927-9902; Fax: +81-89-927-9902 Received: 28 June 2011 / Accepted: 12 July 2011 / Published: 18 July 2011 Abstract: Bronization and carburization of fine-grain superplastic stainless steel is reviewed, and new experimental results for fine grain Ti88.5Al4.5V3Fe2Mo2 are reported. In superplastic duplex stainless steel, the diffusion of carbon and boron is faster than in non-superplastic duplex stainless steel. Further, diffusion is activated by uniaxial compressive stress. Moreover, non-superplastic duplex stainless steel shows typical grain boundary diffusion; however, inner grain diffusion is confirmed in superplastic stainless steel. The presence of Fe and Cr carbides or borides is confirmed by X-ray diffraction, which indicates that the diffused carbon and boron react with the Fe and Cr in superplastic stainless steel. The Vickers hardness of the carburized and boronized layers is similar to that achieved with other surface treatments such as electro-deposition. Diffusion of boron into the superplastic Ti88.5Al4.5V3Fe2Mo2 alloy was investigated. The hardness of the surface exposed to boron powder can be increased by annealing above the superplastic temperature. However, the Vickers hardness is lower than that of Ti boride. Keywords: diffusion; superplasticity; carburization; boronization; duplex stainless steel 1. Introduction The discussion of superplasticity has been performed in many scientific fields, not only materials science and engineering, but also even in the field of earth science [1-7].
    [Show full text]
  • Superplasticity in Metals and Ceramics T.G
    Cambridge University Press 978-0-521-56105-1 - Superplasticity in metals and ceramics T.G. Nieh, J. Wadsworth and O.D. Sherby Excerpt More information Chapter 1 Introduction Interest in superplasticity is extremely high. The major areas include superplastic- ity in metals, ceramics, intermetallics, and composites. Superplasticity at very high strain rates (i.e., approximately 0.1-1 s"1) is an area of strong emphasis that is expected to lead to increased applications of superplastic-forming technology. Historically, there has been no universally accepted definition for super- plasticity. After some debate, the following version was proposed and accepted at the 1991 International Conference on Superplasticity in Advanced Materials (ICSAM-91) held in Osaka, Japan [1]: Superplasticity is the ability of a polycrystalline material to exhibit, in a generally isotropic manner, very high tensile elongations prior to failure. It is anticipated that there will continue to be some modifications to this definition, but it should serve as a working definition for a phenomenon that was scientifically reported in 1912 [2] and, indeed, may have a far longer history, as described in the following chapter. During the course of the ICSAM-91 Conference [1], many different super- plastic materials were described. A list of those mentioned is presented in Table 1.1 [3]. It is reasonable to infer from the broad range of superplastic materials listed that there is now a good basic understanding of the requirements for devel- oping superplastic structures. This extensive list also indicates that research on superplastic ceramics and intermetallics has increased dramatically in recent years since the first superplastic ceramic was not observed until 1985 and the first superplastic intermetallic until 1987.
    [Show full text]