This book covers the physical metallurgy of steels as well as the heat treatments used to improve the their properties. A full chapter is dedicated to the atmospheres in the steelmaking, including the implications of the own gases generated in the iron and steelmaking factories and how they could be applied in these treatments. This book is specially conceived for graduate and undergraduate courses, being the result of more than 30 years of teaching experience in courses for undergraduate, graduate (master and Ph. D.), and companies (technicians). The trends in the re-utilization of industrial gases in the iron and steelmaking process are discussed by the authors. Additionally, the book comprises 41 solved exercises, problems and case-studies, as a complement of the theoretical sections of the text. These exercises, problems, and case-studies are based on problems observed in the industrial practice.
Author(s): José Ignacio Verdeja González, Daniel Fernández-González, Luis Felipe Verdeja González
Series: Topics in Mining, Metallurgy and Materials Engineering
Publisher: Springer
Year: 2022
Language: English
Pages: 342
City: Cham
Acknowledgements
Prologue
Contents
1 Solid-State Transformations in the Iron Carbon System
1.1 Introduction
1.2 Crystalline Structures of the Iron
1.3 Solid Solutions in the Iron
1.3.1 Substitutional Solid Solutions
1.3.2 Interstitial Solid Solutions
1.3.3 Hardness
1.3.4 Tensile Test
1.3.5 Toughness
1.4 Alphagenous and Gammagenous Character of the Elements Solubilized in the Iron
1.5 The Metastable Fe–C Equilibrium Diagram
1.5.1 Steels with 2.11% C
1.5.2 Transformations by Equilibrium Cooling of Hypoeutectoid Steels (<0.77% C)
1.5.3 Hypoeutectoid Steels with <0.02% C
1.6 Influence of Alloying Elements in the Fe–C Metastable Diagram
1.7 Non-equilibrium Transformations by Isothermal Cooling of the Austenite
1.7.1 Metallography and Kinetics of the Pearlitic Transformations
1.7.2 Bainitic Transformations
1.7.3 TTT Curves (Transformation-Temperature-Time Curves)
1.8 Transformation of the Austenite into Martensite
1.8.1 Crystalline Structure and Hardness of the Martensite
1.8.2 Ms Temperature
1.8.3 Thermal Difference (θγ –T) and Residual Austenite
1.8.4 Stabilization of the Austenite by Interruption in the Cooling at T < Ms
1.9 Complementary Considerations About the Ferritic-Pearlitic Transformations
1.9.1 Ferritic-Pearlitic Transformations of the Austenite by Continuous Cooling
1.9.2 Ferritic-Pearlitic Transformations in Low Alloy Steels
1.10 Designation and Normalization of Steels
1.10.1 Different Methods to Designate Steels
1.10.2 International Standards for Steels
References
2 Heat Treatment of Steels
2.1 Introduction
2.2 Austenitization
2.2.1 Heating to Austenitize
2.2.2 Cooling from the Austenitic State
2.3 Annealing to Soften the Steel
2.3.1 Full Annealing
2.3.2 Intercritical Annealing
2.3.3 Isothermal Annealing
2.3.4 Subcritical Annealing
2.4 Normalizing
2.5 Quenching
2.5.1 Hardenability
2.5.2 Susceptibility to Cracking Due to Quenching
2.5.3 Surface Quenching
2.6 Tempering
2.6.1 General Questions
2.6.2 Stages of the Martensite Tempering
2.6.3 T1 Temperature and Time t in the Tempering
2.6.4 Multiple Tempering Treatments
2.7 Isothermal Treatments
2.7.1 Patenting
2.7.2 Austempering
2.7.3 Martempering
2.7.4 Sub-Zero Treatments
2.8 Surface Thermochemical Treatments
2.9 Hyperquenching and Aging
References
3 Thermomechanical Treatments of Steels
3.1 Recrystallization
3.2 Hot Deformation
3.3 Improvements by Hot Forming of the Solidification Structures
3.3.1 Forge Fibering and Crystalline Texture. Anisotropy of Properties
3.4 Thermomechanical Treatments of the Austenite Before Their Allotropic Transformation
3.4.1 Banded Structure
3.4.2 Controlled Rolling
3.4.3 LT Ausforming
3.5 Thermomechanical Treatments of the Austenite During Its Allotropic Transformation
3.5.1 Isoforming
3.5.2 TRIP Effect
3.6 Thermomechanical Treatments After the Transformation of the Austenite
3.6.1 Pearlite Forming
3.6.2 Martensite Forming
References
4 Controlled Atmospheres in Furnaces for Heat Treatments
4.1 Introduction
4.2 Formation and Dissociation of Metallic Oxides: Ellingham’s Diagram
4.3 Reduction of Oxides with Gases
4.3.1 Reduction of an Oxide MxOy in the Presence of a CO–CO2 Gaseous Mixture
4.3.2 Reduction of an Oxide MxOy with H2
4.3.3 Reductant or Oxidizing Aptitude of CO–CO2–H2–H2Ovapor Gases Mixture in Equilibrium
4.4 Case-Hardening and Decarburizing of Steels
4.4.1 Boudouard’s Equilibrium
4.4.2 Decarburizing-Case Hardening in a CO–CO2 Binary Atmosphere
4.4.3 Decarburizing-Case Hardening in a Binary Atmosphere of H2–CH4
4.4.4 Mixture of Gases CO–CO2–H2–CH4–H2O in Equilibrium
4.5 Industrial Atmospheres: C–H–O–N System
4.5.1 Introduction
4.5.2 Endothermic and Exothermic Atmospheres
4.5.3 Atmospheres Obtained from NH3
4.5.4 The Future of the Industrial Atmospheres
4.6 Complementary Considerations
References
Appendices
Appendix 1
Appendix 2
