Theory of Transformations in Steels

604 Pages·2021·115.752 MB·English

by  Harshad K. D. H. Bhadeshia

Theory of Transformations
in Steels

Theory of Transformations
in Steels
Harshad K. D. H. Bhadeshia
First edition published 2021
by CRC Press
6000 Broken Sound Parkway NW, Suite 300, Boca Raton, FL 33487-2742
and by CRC Press
2 Park Square, Milton Park, Abingdon, Oxon, OX14 4RN
© 2021 Taylor & Francis Group, LLC
CRC Press is an imprint of Taylor & Francis Group, LLC
The right of Harshad K. D. H. Bhadeshia to be identified as author of this work has been asserted by him in accordance
with sections 77 and 78 of the Copyright, Designs and Patents Act 1988.
Reasonable efforts have been made to publish reliable data and information, but the author and publisher cannot
assume responsibility for the validity of all materials or the consequences of their use. The authors and publishers
have attempted to trace the copyright holders of all material reproduced in this publication and apologize to copyright
holders if permission to publish in this form has not been obtained. If any copyright material has not been acknowl-
edged please write and let us know so we may rectify in any future reprint.
Except as permitted under U.S. Copyright Law, no part of this book may be reprinted, reproduced, transmitted, or
utilized in any form by any electronic, mechanical, or other means, now known or hereafter invented, including pho-
tocopying, microfilming, and recording, or in any information storage or retrieval system, without written permission
from the publishers.
For permission to photocopy or use material electronically from this work, access www.copyright.com or contact the
Copyright Clearance Center, Inc. (CCC), 222 Rosewood Drive, Danvers, MA 01923, 978-750-8400. For works that are
not available on CCC please contact [email protected]
Trademark notice: Product or corporate names may be trademarks or registered trademarks and are used only for
identification and explanation without intent to infringe.
Library of Congress Cataloging-in-Publication Data
Names: Bhadeshia, H. K. D. H. (Harshad Kumar Dharamshi Hansraj), 1953-
author.
Title: Theory of transformations in steels / Harshad K.D.H. Bhadeshia.
Description: Boca Raton : CRC Press, 2021. | Includes bibliographical
references and indexes. | Summary: “Written by the leading authority in
the field, this work is the first to provide readers with a complete
discussion of the theory of transformations in steel. It offers
comprehensive treatment of solid-state transformations, covering the
vast number in steels. It features discussion of physical properties,
thermodynamics, diffusion, and kinetics and covers ferrites, martensite,
cementite, carbides, nitrides, substitutionally-alloyed precipitates,
and pearlite. It also contains a comprehensive list of references as
further and recommended reading. With its broad and deep coverage of
the subject, this work aims at inspiring research within the field of materials
science and metallurgy”-- Provided by publisher.
Identifiers: LCCN 2020043503 (print) | LCCN 2020043504 (ebook) | ISBN
9780367518080 (hardback) | ISBN 9781003056782 (ebook)
Subjects: LCSH: Steel alloys. | Physical metallurgy. | Phase
transformations (Statistical physics)
Classification: LCC TN756 .B49 2021 (print) | LCC TN756 (ebook) | DDC
669/.96142--dc23
LC record available at https://lccn.loc.gov/2020043503
LC ebook record available at https://lccn.loc.gov/2020043504
ISBN: 978-0-367-51808-0 (hbk)
ISBN: 978-1-003-05678-2 (ebk)
Typeset in Computer Modern font
by KnowledgeWorks Global Ltd.
To my late father and mother.

Contents
Preface..............................................................................................................................................xv
Author.............................................................................................................................................xix
Acronymsetc..................................................................................................................................xxi
Nomenclature................................................................................................................................xxiii
Chapter1 Crystalstructuresandmechanisms.........................................................................1
1.1 Allotropesofiron............................................................................................1
1.2 Theillousaryomegaphase.............................................................................5
1.3 Amorphousiron..............................................................................................6
1.4 Mechanismsoftransformation.......................................................................6
1.5 Crystallographicsimilarities...........................................................................8
1.6 Iron-carbonphasediagram.............................................................................9
1.7 Classificationscheme....................................................................................11
1.7.1 ThermodynamicClassification........................................................13
Chapter2 Thermodynamics...................................................................................................17
2.1 Introduction...................................................................................................17
2.2 Definitions.....................................................................................................17
2.2.1 Internalenergyandenthalpy............................................................17
2.2.2 Entropy,freeenergy.........................................................................18
2.2.3 Configurationalentropy...................................................................18
2.2.4 RelationshipbetweenClausiusandBoltzmannentropies...............19
2.3 Maxwellrelations.........................................................................................20
2.4 Thermodynamicfunctionsofiron................................................................20
2.4.1 RelationbetweenC andC ............................................................22
P V
2.4.2 DebyeTemperatures........................................................................22
2.5 Electronicheatcapacity................................................................................23
2.6 Magneticspecificheatofiron.......................................................................24
2.6.1 Diamagnetism..................................................................................25
2.6.2 Paramagnetism.................................................................................25
2.6.3 Ferromagnetism,antiferromagnetismandferrimagnetism..............26
2.6.4 Heatcapacityduetomagnetisation.................................................27
2.6.5 Magneticheatcapacityofferrite.....................................................28
2.6.6 Magneticheatcapacityofaustenite.................................................30
2.6.7 Invareffectandassociatedphenomena............................................35
ε
2.6.8 Magneticheatcapacityof -Ironandsuperconductivity...............38
2.6.9 Trigonalandtetragonaliron.............................................................39
2.7 Heatcapacityofliquidiron..........................................................................44
2.8 Freeenergyfunctionsofiron........................................................................44
2.8.1 Liquidiron.......................................................................................45
vii
viii Contents
2.9 Effectofpressure..........................................................................................47
2.9.1 Liquidiron.......................................................................................47
2.9.2 Ferriteandaustenite.........................................................................48
2.9.3 Hexagonalclose-packediron...........................................................49
2.10 Mechanicalmixturesandsolutions..............................................................49
2.10.1 Alloyingbydeformation..................................................................49
2.11 Chemicalpotential........................................................................................51
2.12 Equilibriumbetweensolutions.....................................................................52
2.13 Activity.........................................................................................................53
2.14 Idealsolution................................................................................................54
2.15 Regularsolutions..........................................................................................55
2.16 Quasichemicalsolution.................................................................................57
2.17 quasichemicalmodelforcarboninaustenite................................................61
2.17.1 Dilutesolution,ω →0limit..........................................................66
γ
2.17.2 Infiniterepulsionlimit.....................................................................66
2.17.3 Zeroth-orderquasichemicalmodel..................................................67
2.17.4 Referencestateforcarbon...............................................................67
2.17.5 Carbon-carboninteractionenergyinaustenite................................67
2.17.6 Carbon-carboninteractionenergyinferrite.....................................70
2.18 Zenerordering..............................................................................................71
2.19 Computercalculationofphasediagrams......................................................72
2.19.1 Stoichiometricphases:regularsolutionmodel................................73
2.19.2 Interstitialsolution...........................................................................74
2.19.3 Generalisedregularsolutionmodel.................................................77
2.19.4 Magneticeffects...............................................................................78
2.19.5 Magnetisation...................................................................................84
2.20 Orderparameter............................................................................................84
2.20.1 Short-rangeorder.............................................................................86
2.21 Superlattices..................................................................................................87
2.21.1 Orderedcrystals...............................................................................87
2.22 Thermodynamicsofirreversibleprocesses...................................................88
2.22.1 Reversibility.....................................................................................89
2.22.2 Linearlaws.......................................................................................90
2.22.3 Multipleirreversibleprocesses........................................................91
2.22.4 Onsagerreciprocalrelations............................................................92
Chapter3 Diffusion..............................................................................................................103
3.1 Introduction.................................................................................................103
3.2 Fick’slawanddiffusioncoefficients..........................................................103
3.2.1 Reactionrateexpression................................................................107
3.3 Diffusionofcarboninferrite......................................................................107
3.3.1 Interstitialsitesinferrite................................................................107
3.3.2 Dual-siteoccupancy.......................................................................110
3.4 Diffusionofcarboninmartensite...............................................................112
3.5 Interactionsbetweencarbonatoms.............................................................114
3.5.1 Repulsionbetweencarbonatoms...................................................114
3.5.2 Clusteringofinterstitialatoms.......................................................115
3.5.3 Associationofcarbonwithdefects................................................117
3.6 Diffusionofcarboninaustenite..................................................................119
3.6.1 Dependenceofdiffusivityoncomposition....................................119
Contents ix
3.6.2 DependenceofdiffusivityonC-Cinteractions..............................121
3.6.3 Dilatationeffects............................................................................123
3.6.4 A˚gren’smethod..............................................................................125
3.7 Diffusionofnitrogeninferrite....................................................................126
3.8 Diffusionofnitrogeninaustenite...............................................................127
3.9 DiffusionofCandNincementiteandHa¨ggcarbide.................................127
3.10 Migrationofpointdefects..........................................................................129
3.10.1 Ironinterstitials..............................................................................129
3.10.2 Irondefectsinaustenite.................................................................130
3.10.3 Vacancies........................................................................................131
3.11 Migrationofhydrogenanddeuterium........................................................132
3.11.1 Diffusioninferrite.........................................................................132
3.11.2 Diffusionofhydrogeninaustenite.................................................133
3.11.3 Hydrogen-vacancyinteractions......................................................134
3.12 Self-diffusioniniron...................................................................................134
3.12.1 Theisotopeeffect...........................................................................138
3.13 Magnetismandinterstitialdiffusioninferrite............................................139
3.14 Substitutionalsolutes..................................................................................140
3.15 Grainboundarydiffusion............................................................................142
3.16 Phenomenologicaltreatmentofbinarydiffusion........................................143
3.17 Diffusioninmulticomponentsystems........................................................144
3.17.1 DiffusioninternaryFe-X-Calloys................................................145
3.18 Diffusioninliquidiron...............................................................................148
3.19 Stress-inducedmigration............................................................................149
3.20 Electromigration.........................................................................................150
3.21 Thermomigration........................................................................................153
3.22 Electropulsing.............................................................................................154
Chapter4 Ferritebyreconstructivetransformation.............................................................165
4.1 Introduction.................................................................................................165
4.2 Interfaces.....................................................................................................167
4.2.1 Coherency......................................................................................167
4.2.2 Glissilesemi-coherentinterfaces...................................................168
4.2.3 Sessilesemi-coherentinterfaces....................................................169
4.2.4 Incoherentinterfaces......................................................................170
4.3 Crystallography...........................................................................................170
4.3.1 Orientationrelationships................................................................170
4.3.2 Theγ/αinterface..........................................................................174
4.4 Nucleationofallotriomorphicandidiomorphicferrite..............................174
4.4.1 Heterogeneousnucleationfromvapour.........................................178
4.4.2 Heterogeneousnucleationoninclusions........................................180
4.5 Interfacemotion:rate-controllingprocesses..............................................184
4.6 Diffusion-controlledgrowth.......................................................................187
4.6.1 GrowthinFe-CAlloys...................................................................187
4.6.2 Lengtheningofferriteallotriomorphs............................................190
4.6.3 Softimpingement...........................................................................191
4.6.4 Phasefields.....................................................................................192
4.6.5 FerritegrowthinFe-X-Calloys:localequilibrium.......................194
4.6.6 Interface-compositioncontours.....................................................200
4.6.7 Interface-velocity(IV)contours.....................................................201