Theory of Transformations in Steels

Description

Written by the leading authority in the field of solid-state phase transformations, Theory of Transformations in Steels is the first book to provide readers with a complete discussion of the theory of transformations in steel. Offers comprehensive treatment of solid-state transformations, covering the vast number in steels Serves as a single source for almost any aspect of the subject Features discussion of physical properties, thermodynamics, diffusion, and kinetics Covers ferrites, martensite, cementite, carbides, nitrides, substitutionally-alloyed precipitates, and pearlite Contains a thoroughly researched and 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. Cover Half Title Title Page Copyright Page Dedication Contents Preface Author Acronyms etc. Nomenclature Chapter 1: Crystal structures and mechanisms 1.1. Allotropes of iron 1.2. The illousary omega phase 1.3. Amorphous iron 1.4. Mechanisms of transformation 1.5. Crystallographic similarities 1.6. Iron-carbon phase diagram 1.7. Classification scheme 1.7.1. Thermodynamic Classification Chapter 2: Thermodynamics 2.1. Introduction 2.2. Definitions 2.2.1. Internal energy and enthalpy 2.2.2. Entropy, free energy 2.2.3. Configurational entropy 2.2.4. Relationship between Clausius and Boltzmann entropies 2.3. Maxwell relations 2.4. Thermodynamic functions of iron 2.4.1. Relation between CP and CV 2.4.2. Debye Temperatures 2.5. Electronic heat capacity 2.6. Magnetic specific heat of iron 2.6.1. Diamagnetism 2.6.2. Paramagnetism 2.6.3. Ferromagnetism, antiferromagnetism and ferrimagnetism 2.6.4. Heat capacity due to magnetisation 2.6.5. Magnetic heat capacity of ferrite 2.6.6. Magnetic heat capacity of austenite 2.6.7. Invar effect and associated phenomena 2.6.8. Magnetic heat capacity of E-Iron and superconductivity 2.6.9. Trigonal and tetragonal iron 2.7. Heat capacity of liquid iron 2.8. Free energy functions of iron 2.8.1. Liquid iron 2.9. Effect of pressure 2.9.1. Liquid iron 2.9.2. Ferrite and austenite 2.9.3. Hexagonal close-packed iron 2.10. Mechanical mixtures and solutions 2.10.1. Alloying by deformation 2.11. Chemical potential 2.12. Equilibrium between solutions 2.13. Activity 2.14. Ideal solution 2.15. Regular solutions 2.16. Quasichemical solution 2.17. Quasichemical model for carbon in austenite 2.17.1. Dilute solution, w !0 limit 2.17.2. Infinite repulsion limit 2.17.3. Zeroth-order quasichemical model 2.17.4. Reference state for carbon 2.17.5. Carbon-carbon interaction energy in austenite 2.17.6. Carbon-carbon interaction energy in ferrite 2.18. Zener ordering 2.19. Computer calculation of phase diagrams 2.19.1. Stoichiometric phases: regular solution model 2.19.2. Interstitial solution 2.19.3. Generalised regular solution model 2.19.4. Magnetic effects 2.19.5. Magnetisation 2.20. Order parameter 2.20.1. Short-range order 2.21. Superlattices 2.21.1. Ordered crystals 2.22. Thermodynamics of irreversible processes 2.22.1. Reversibility 2.22.2. Linear laws 2.22.3. Multiple irreversible processes 2.22.4. Onsager reciprocal relations Chapter 3: Diffusion 3.1. Introduction 3.2. Fick’s law and diffusion coefficients 3.2.1. Reaction rate expression 3.3. Diffusion of carbon in ferrite 3.3.1. Interstitial sites in ferrite 3.3.2. Dual-site occupancy 3.4. Diffusion of carbon in martensite 3.5. Interactions between carbon atoms 3.5.1. Repulsion between carbon atoms 3.5.2. Clustering of interstitial atoms 3.5.3. Association of carbon with defects 3.6. Diffusion of carbon in austenite 3.6.1. Dependence of diffusivity on composition 3.6.2. Dependence of diffusivity on C-C interactions 3.6.3. Dilatation effects 3.6.4. Agren’s method 3.7. Diffusion of nitrogen in ferrite 3.8. Diffusion of nitrogen in austenite 3.9. Diffusion of C and N in cementite and Hagg carbide 3.10. Migration of point defects 3.10.1. Iron interstitials 3.10.2. Iron defects in austenite 3.10.3. Vacancies 3.11. Migration of hydrogen and deuterium 3.11.1. Diffusion in ferrite 3.11.2. Diffusion of hydrogen in austenite 3.11.3. Hydrogen-vacancy interactions 3.12. Self-diffusion in iron 3.12.1. The isotope effect 3.13. Magnetism and interstitial diffusion in ferrite 3.14. Substitutional solutes 3.15. Grain boundary diffusion 3.16. Phenomenological treatment of binary diffusion 3.17. Diffusion in multicomponent systems 3.17.1. Diffusion in ternary Fe-X-C alloys 3.18. Diffusion in liquid iron 3.19. Stress-induced migration 3.20. Electromigration 3.21. Thermomigration 3.22. Electropulsing Chapter 4: Ferrite by reconstructive transformation 4.1. Introduction 4.2. Interfaces 4.2.1. Coherency 4.2.2. Glissile semi-coherent interfaces 4.2.3. Sessile semi-coherent interfaces 4.2.4. Incoherent interfaces 4.3. Crystallography 4.3.1. Orientation relationships 4.3.2. The = Interface 4.4. Nucleation of allotriomorphic and idiomorphic ferrite 4.4.1. Heterogeneous nucleation from vapour 4.4.2. Heterogeneous nucleation on inclusions 4.5. Interface motion: rate-controlling processes 4.6. Diffusion-controlled growth 4.6.1. Growth in Fe-C Alloys 4.6.2. Lengthening of ferrite allotriomorphs 4.6.3. Soft impingement 4.6.4. Phase fields 4.6.5. Ferrite growth in Fe-X-C alloys: local equilibrium 4.6.6. Interface-composition contours 4.6.7. Interface-velocity (IV) contours 4.6.8. Tie-line shifting due to soft impingement 4.6.9. Invalidity of the NP-LE concept 4.7. Breakdown of local equilibrium 4.7.1. Paraequilibrium 4.7.2. Solute and solvent trapping 4.8. Interface-controlled growth 4.8.1. Pure iron 4.8.2. Iron alloys 4.9. Growth with mixed control 4.10. Step mechanism of interfacial motion 4.10.1. Boundary topology, ledge nucleation 4.10.2. Motion of isolated ledge 4.10.3. Multiledge interactions 4.10.4. Ledge motion in finite medium 4.10.5. Relative kinetics of stepped and continuous growth 4.11. Solute drag: grain boundaries 4.11.1. Solute drag and diffusion coefficients 4.11.2. Interaction free energy 4.12. Solute drag: interphase boundaries 4.12.1. Segregation to = interfaces 4.13. Massive ferrite 4.14. Interphase precipitation 4.14.1. Interphase precipitation: theory Chapter 5: Martensite 5.1. Diffusionless transformations 5.2. Other characteristics of martensite 5.2.1. Habit plane 5.2.2. Orientation relationships 5.2.3. Structure of the interface 5.2.4. Shape deformation 5.2.5. Microstructure 5.2.6. Summary 5.2.7. Crystallographic theory 5.3. Quantitative theory 5.3.1. fcc to bcc martensitic transformation 5.4. "-martensite 5.4.1. Crystallography: fcc to hcp transformation 5.4.2. !" transformation 5.5. Martensite-start temperature 5.5.1. Effect of austenite grain size on MS 5.6. Thermodynamics 5.6.1. Thermoelastic equilibrium 5.7. Martensite: nucleation mechanism 5.7.1. fcc to hcp transformation 5.7.2. Role of thermal activation 5.7.3. fcc to bcc transformation 5.7.4. Nucleation at large driving forces 5.8. Overall transformation kinetics 5.8.1. Partitioning of austenite 5.8.2. Athermal transformation 5.8.3. Isothermal martensite 5.8.4. Bursts of transformation 5.9. Stress AND strain effects 5.9.1. Transformation texture 5.9.2. Mechanical stabilisation 5.10. Tetragonality of martensite Chapter 6: Bainite 6.1. Microstructure 6.2. More about the mechanism 6.2.1. Stage 1: vestiges 6.2.2. Stage 2a: carbon partitioning 6.2.3. Stage 2b: precipitation from ferrite 6.2.4. Stage 3: termination 6.3. Kinetics Chapter 7: Widmanstatten ferrite 7.1. Introduction 7.2. Crystallography 7.3. Accommodation of shape deformation 7.3.1. Interfacial structure 7.3.2. Mechanical stabilisation 7.4. Transformation-start temperature 7.5. Mechanism of nucleation 7.6. Rationalisation of shear transformations 7.7. Nucleation rate 7.8. Capillarity 7.9. Growth of Widmanstatten ferrite 7.9.1. Interface-controlled growth 7.9.2. Groups of plates 7.10. Plate thickening 7.11. Growth from allotriomorphic ferrite Chapter 8: Cementite 8.1. Crystal structure of cementite 8.1.1. Types of interstitial sites 8.2. Carbon content of cementite 8.3. Magnetic properties 8.4. Thermal properties 8.5. Surface energy 8.6. Elastic properties of single crystalline cementite 8.7. Elastic properties of polycrystalline cementite 8.8. Substitutional solutes 8.8.1. Precipitates inside cementite 8.9. Thermodynamic properties 8.9.1. Heat capacity 8.9.2. Equilibrium between cementite and matrix dislocations 8.9.3. Graphitisation and synthesis 8.10. Cementite precipitation in metallic glass 8.11. Carbon nanotubes – role of cementite 8.12. Displacive mechanism of cementite precipitation 8.13. = orientation relations in pearlite 8.14. Pitsch = orientation relationship Chapter 9: Other Fe-C carbides 9.1. Generic considerations 9.1.1. Observations of x, n, " and 0 carbides in tempered Fe-C 9.2. X-carbide 9.3. n-carbide 9.4. "-carbide 9.4.1. Elastic moduli of "-carbide Chapter 10: Nitrides 10.1. 0-nitride 10.2. "-nitrides 10.3. -Fe2N 10.4. 00-Fe16N2 10.5. Z-phase 10.6. Nb(CN), CrN, TiN, Cr2N, AlN Chapter 11: Substitutionally alloyed precipitates 11.1. TiC, NbC 11.2. Vanadium carbide 11.3. M23C6 11.4. M6C 11.5. M7C3 11.6. Mo2C 11.7. -carbide 11.8. Laves phase 11.9. Other intermetallic compounds 11.9.1. NiAl 11.9.2. s-phase 11.9.3. -phase 11.9.4. Iron-zinc compounds 11.10. Competitive precipitation and dissolution Chapter 12: Pearlite 12.1. Shape 12.2. Nucleation 12.3. Growth 12.4. Fe-C-X: growth with local equilibrium 12.4.1. Local equilibrium? 12.5. Forced velocity pearlite 12.6. Pearlite not containing cementite 12.7. Divorced eutectoid transformation Chapter 13: Aspects of kinetic theory 13.1. Grain growth 13.2. Recrystallisation 13.2.1. Phenomenological treatment of recrystallisation 13.2.2. Thermomechanical processing: limits to grain refinement 13.3. Overall transformation kinetics 13.3.1. Isothermal transformation 13.4. Simultaneous transformations 13.4.1. Basis of microstructural models 13.4.2. Allotriomorphic ferrite 13.4.3. Widmanstatten ferrite and pearlite 13.5. Time-temperature-transformation diagrams 13.5.1. Continuous cooling transformation diagrams Author index Subject index