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Recrystallization and Related Annealing Phenomena Third Edition John Humphreys Gregory S. Rohrer Anthony Rollett Elsevier Radarweg29,POBox211,1000AEAmsterdam, Netherlands The Boulevard,LangfordLane,Kidlington,OxfordOX51GB,UnitedKingdom 50HampshireStreet,5thFloor,Cambridge,MA02139,UnitedStates Copyright©2017Elsevier Ltd.Allrightsreserved. Nopart ofthispublicationmaybereproduced ortransmittedinanyformorbyanymeans,electronic or mechanical, includingphotocopying,recording,oranyinformationstorageand retrievalsystem,without permission inwriting fromthepublisher.Detailsonhowtoseekpermission,furtherinformationaboutthe Publisher’spermissionspolicies andourarrangementswithorganizationssuchastheCopyrightClearance Center andtheCopyrightLicensingAgency,canbefoundatourwebsite:www.elsevier.com/permissions. Thisbookandtheindividualcontributionscontainedinitare protected undercopyrightbythePublisher (otherthanasmaybenotedherein). 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LibraryofCongressCataloging-in-Publication Data Acatalogrecordforthisbookisavailablefrom theLibraryofCongress British LibraryCataloguing-in-PublicationData Acatalogue recordforthisbookisavailablefrom theBritishLibrary ISBN:978-0-08-098235-9 ForinformationonallElsevier publicationsvisitour websiteathttps://www.elsevier.com/books-and-journals Publisher:JohnFedor Acquisition Editor:KostasMarinakis Editorial ProjectManager:MichelleFisher ProductionProjectManager:VijayarajPurushothaman Designer: GregHarris TypesetbyTNQBooksandJournals Preface to the First Edition Recrystallization and the related annealing phenomena which occur during the thermomechanical processing of materials have long been recognized as being both of technological importance and scientific interest. These phenomena are known to occur in all types of crystalline materials; they occur during the natural geological deformation of rocks and minerals, and during the processing of technical ceramics. However, the phenomena have been most widely studied in metals, and as this is the only class of material for which a coherent body of work is available, this book inevitably concentrates on metallic materials. Although there is a vast body of literature going back 150years, and a large collection of reviews which are detailed in Chapter 1, there have only been two monographs published in recent times on the subject of recrystallization, the latest nearly 20years ago. Since that time, considerable advances have been made, both in our understanding of the subject and in the techniques available to the researcher. Metallurgical research in this field is mainly driven by the requirements of industry, and currently, a major need is for quantitative, physically based models which can be applied to metal-forming processes so as to control, improve and optimize the microstructure and texture of the finished products. Such models require a more detailed understanding of both the deformation and annealing processes than we have at present. The development of the underlying science to a level sufficient for the construction of the required models from first principles provides a goal for perhaps the next 10e20years. Thebook waswritten toprovide atreatmentof thesubjectfor researchersor students who need a moredetailed coverage thanisfoundintextbooks onphysical metallurgy, and a more coherent treatment thanwill befound inthe many conference proceedings. We have chosen toemphasizethe scientific principlesand physical insight underlyingannealing rather thanproducea comprehensive bibliography orhandbook. Unfortunately the generic term annealing is used widely to describe two metallurgical processes. Both have a common result in that a hardened material is made softer, but the mechanisms involved are quite different. In one case, associated with the heat treatment xv Preface to the First Edition offerrous materials, the softening process involves the g/a phase transformation. In the second case, which is the one relevant to this book, the softening is a direct result of the loss via recovery and recrystallization, of the dislocations introduced by work hardening. It is not easy towrite a book on recrystallization, because although it is a clearly defined subject, many aspects are not well understood and the experimental evidence is often poor and conflicting. It would have been desirable to quantify all aspects of the phenomena and to derive the theories from first principles. However, this is not yet possible, and the reader will find within this book a mixture of relatively sound theory, reasonable assumptions and conjecture. There are two main reasons for our lack of progress. First, we cannot expect to understand recovery and recrystallization in depth unless we understand the nature of the deformed statewhich is the precursor, and that is still a distant goal. Second, although some annealing processes, such as recovery and grain growth are reasonably homogeneous, others, such as recrystallization and abnormal grain growth are heterogeneous, relying on local instabilities and evoking parallels with apparently chaotic events such as weather. It must be recognized that we are writing about a live and evolving subject. Very little is finished and the book should therefore be seen as a snapshot of the subject at this particular time as seen by two scientists who are undoubtedly biased in various ways. We hope that when a second edition of this volume is produced in perhaps 10years time, or a new treatment is attempted, many aspects of the subject will have become clearer. Recovery and recrystallizationdependonthe natureofthe deformed stateand involve theformation,removalandmovement ofgrainboundaries.Forthese reasonswehave included treatmentsofthe deformed stateinChapter2,andthe nature ofgrainboundaries in Chapter3.Theseare both largetopics whichmeritcompletebooksinthemselves, and we have not attempteda comprehensive coverage but havemerelyaimedtoprovidewhat weregard asessentialbackground informationin orderto make thevolumereasonably self-contained. Chapter4 isconcernedwith the migrationand mobilityof grainboundaries, andthis containssomebackgroundinformation. Themaintopics ofthe bookdrecovery,recrystallizationandgraingrowthdare covered in Chapters5e11andincludespecific chaptersonordered materials,two-phase alloys andannealing textures. Inorder toillustratesomeofthe applicationsof theprinciples discussed inthe bookwehave selectedavery few technologicallyimportantcasestudiesin Chapter 12. The finalchapteroutlines theways inwhich computer simulationandmodeling arebeingappliedto annealingphenomena,andintheappendix weprovideanintroduction to themeasurementandrepresentationoftextures for thebenefitofreaderswhoarenot specialistsinthis area. xvi Preface to the First Edition John Humphreys ManchesterMaterialsScience Centre Universityof ManchesterInstitute ofScienceand Technology UK Max Hatherly School ofMaterials University ofNew South Wales Australia August 1994 Theneed toreprint the bookhasprovided anopportunityfor ustocorrectsomeofthe errors and tocarryoutminor modificationstothe text. May1996 xvii Preface to the Second Edition This second edition has a similar philosophy and format to the first, although developments in the subject have necessitated some significant changes. Recrystallization remains a very active research area, judging by the number of publications and conferences on this and related areas, and the continuing developments in many areas make it a difficult subject to capture. As in the preface to the first edition, we ask the reader to remember that this book presents a personal view of the subject, at a particular moment in time. There have been two important changes in methods of investigating and analyzing recrystallization since the first edition. The first is in the experimental determination of microstructure and texture, where the increase in the power and application of the Electron Backscatter Diffraction (EBSD) technique has provided data of a type which was previously unavailable, and many examples of its use are included in the book. The other change is in the increased amount of modeling and simulation of annealing processes which is now carried out. In terms of the subject areas covered in the first edition of the book, there has been significant new activity in two areas of fundamental importance to the understanding of recrystallization; the characterization of the deformed state, and the measurement of grain boundary properties. Some new areas have also opened up. In the first edition we briefly mentioned new research which indicated that deformation to very large strains might lead to microstructural stability on subsequent annealing. This has now become a major research area which is not only of scientific interest, but is also a potential method of producing strong alloys, and this is given detailed coverage in this edition. Developments in this and other areas have highlighted the difficulties of applying the traditional terminologies to new phenomena, and it is now considered necessary to subdivide recovery, recrystallization and grain growth into “discontinuous” and “continuous” variants. Changes inthe layoutof thebook includea separationof deformationmicrostructure (Chapter2)anddeformation texture (Chapter 3),introductionofa simpleanalyticalmodel which embraces recovery, recrystallizationand graingrowth(Chapter10),a consideration xix Preface to the Second Edition of continuous recrystallizationduring and afterlarge straindeformation(Chapter14),anda summaryof themethods ofmeasuring recrystallization(Appendix2). Finally, accesstovideoclipsofsomeinsitu annealingexperimentsandsimulations which maybeofinterest,isprovided atthe Website:http://www.recrystallization.info. John Humphreys MaxHatherly April2003 xx Preface to the Third Edition This thirdeditionhewscloselytoitspredecessors withsignificant additionsincertainareas where substantial advanceshave accumulated.Inallareas,the texthas been reviewedand, where appropriate,re-written toaccountfor recentadditionstotheliterature. Concerning the authorship,MaxHatherlyisnolongerwith us, sadly;JohnHumphreys hasretired and is nottobe blamed foranyerrors ormistakes thatwemayhaveintroduced inthisnew edition. Intermsofcontent, computer modeling ofgrainboundarieshas resulted innew insights about theirproperties,especiallyenergyand mobility.Thecombinationof automated serial sectioning and synchrotron-based characterizationhasprovided 3-D maps ofmicrostructureandadditionalnew insights.The descriptions ofwork hardening and texture have beenstrengthened. AnthonyRollett Gregory Rohrer August 2017 xxi Acknowledgments Figures have been reproduced with permission from the following sources: ThefollowingfiguresarecopiedfromActaMaterialiawiththepermissionofElsevierScience, P.O.Box800,OxfordOX51DX:Fig.13.10fromNes,E.,Marthinsen,K.2002toDaalandand Nes1995.OriginofcubetextureduringhotrollingofcommercialAleMneMgalloys.Mater. Sci.Eng.A322,176(Fig.6).Fig.2.10fromLiu,Q.,JuulJensen,D.,Hansen,N.,1998.Effect ofgrainorientationondeformationstructureincoldrolledaluminium.ActaMater.46,5819 (Fig.2).Fig.16.7fromUpmanyu,M.,Srolovitz,D.J.,Shvindlerman,L.S.,Gottstein,G.,1999. Misorientation/dependenceofintrinsicboundarymobility.ActaMater.47,3901(Fig.2). Fig.4.21fromGoukon,N.,Yamada,T.,Kajihara,M.,2000.BoundaryenergiesofS11 [110]asymmetrictiltboundaries.ActaMater.48,2837(Fig.2).Fig.5.2fromWinning,M., Gottstein,G.,Shvindlerman,L.S.,2001.Stressinducedgrainboundarymotion.ActaMater. 49,211(Figs.12and13).Fig.5.33fromProtasova,S.G.,Gottstein,G.,Sursaeva,V.G., Shvindlerman,L.S.,2001.Triplejunctionmotioninaluminumtricrystals.ActaMater.49, 2519(Fig.5).Fig.2.26fromDuckham,A.,Knutsen,R.D.,Engler,O.,2001.Influence ofdeformationvariablesontheformationofshearbandsinAle1Mg.ActaMater.49, 2739(Fig.3). The following figures are copied from Scripta Materialia with the permission of Elsevier Science, P.O. Box 800, Oxford OX5 IDX: Fig. 5.12 from Molodov, D.A., Czubayko, U., Gottstein, G., Shvindlerman, L.S., 1995. Mobility of <111> tilt grain boundaries in the P vicinity of the special misorientation ¼7 in bicrystals of pure aluminium. Scr. Metall. Mater. 32, 529 (Figs. 4 and 5). On the description of misorientations and interpretation of recrystallisation textures. Scr. Mater. 35, 579 (Fig. 4). Fig. 12.7 from Engler, O., 2001b. An EBSD local texture study on the nucleation of recrystallization at shear bands in the alloy Al %Mg. Scr. Mater. 44, 299 (Fig. 1). Fig. 4.7 from Yang, C.-C., Rollett, A.D., 3 Mullins, W.W., 2001. Measuring relative grain boundary energies and mobilities in an aluminum foil from triple junction geometry. Scr. Mater. 44, 2735 (Fig. 4). The following figures are copied from Materials Science and Engineering, with the permission of Elsevier Science, P.O. Box 800, Oxford OX5 IDX: Fig. 2.5 from Hughes, D.A., 2001. Microstructure evolution, slip patterns and flow stress. Mater. Sci. Eng. A319, xxiii Acknowledgments 46 (Fig. 4). Fig. 2.5b from Nes, E., Marthinsen, K., 2002. Modeling the evolution in microstructure and properties during plastic deformation of f.c.c.-metals and alloys e an approach towards a unified model. Mater. Sci. and Eng. A322, 176 (Fig. 6). Fig. 6.27 from Haslam, A.J., Phillpot, S.R., Wolf, D., Moldovan, D., Gleiter, H., 2001. Mechanisms of grain growth in nanocrystalline fcc metals by molecular-dynamics simulation. Mater. Sci. Eng. A318, 293 (Fig. 4). Fig. 15.3 from Engler, O., Hirsch, J., 2002. Texture control by thermomechanical processing of AA6xxx AleMgeSi sheet alloys for automotive applicationsda review. Mater. Sci. Eng. A336, 249 (Fig. 10). The following figure is copied from Intermetallics, with the permission of Elsevier Science, P.O. Box 800, Oxford OX5 IDX: Fig. 8.7 from Huang, Y.D., Froyen, L., 2002. Recovery, recrystallization and grain growth in Fe Al-Based Alloys. Intermetallics 10, 473 (Fig. 5). 3 The following figures are copied from Materials Science and Technology with the permission of Maney Publishing, 1 Carlton House Terrace, London SW1Y 5DB: Fig. 3.3 from Hirsch, J., 1990b. Correlation of deformation texture and microstructure. Mater. Sci. Technol. 6, 1048 (Fig. 3). Fig. 15.15 from Hayes, J.S., Keyte, R., Prangnell, P.B., 2000. Effect of grain size on tensile behavior of a submicron-grained Ale3wt%Mg alloy. Mater. Sci. Technol. 16, 1259 (Fig. 6). The following figure is copied from Materials Science Forum, with the permission of Trans Tech Publications Ltd., Brandrain 6, CH-8707, Ueticon-Zuerich, Switzerland: Fig. 3.15 from Benum, S., Engler, O., Nes, E., 1994. Mater. Sci. Forum 157e162, 913. In the first edition of this book we acknowledged a great debt to those with whom we had discussed and argued over the subjects covered by this book over a period of very many years. During the writing of the book we had particularly useful discussions and correspondence with Brian Duggan, Bevis Hutchinson, and Erik Nes. A large number of others helped by providing advice, material, and in many other ways. They include Sreeramamurthy Ankem, Mahmoud Ardakani, Christine Carmichael, Michael Ferry, Brian Gleeson, Gunther Gottstein, Brigitte Hammer, Alan Humphreys, Peter Krauklis, Lasar Shvindlerman, Tony Malin, Paul Munroe, Nigel Owen, Phil Prangnell, Fred Scott, Karen Vernon-Parry, and David Willis. A significant amount of the new research which has contributed to the second edition of the book has been carried out in Manchester, and the strong support of the Engineering and Physical Sciences Research Council and Alcan International is gratefully acknowledged. The help, advice, and support of Pete Bate has been particularly valuable, and the Manchester Light Alloy Processing Group, including Philip Prangnell, Norman Ridley, Hedieh Jazaeri, Peter Hurley, Yan Huang, Andrew Clarke, Martin Ashton, Ian Brough, and Matthew Jones, and their provision of data and figures has made a major contribution to this edition. During the preparation of the second edition, critical comments and suggestions xxiv