Steel and Its Heat Treatment

1 Fundamental Metallographic Concepts 1.1 The Transformation and Crystal Structures of Iron 1.2 The Iron-Carbon Equilibrium Diagram 1.2.1 Heating 1.2.2 Cooling 1.3 Time-Temperature-Transformation 1.3.1 Heating 1.3.2 Cooling 1.3.3 Formation of Pearlite 1.3.4 Formation of Bainite 1.3.5 Formation of Martensite 1.3.6 Retained Austenite 1.3.7 TTT Diagrams 1.4 Decomposition of Martensite and Retained Austenite on Tempering 1.5 Diffusion 1.5.1 The Nature of Diffusion 1.5.2 Factors that Influence the Rate of Diffusion 1.5.3 Calculation of Diffusion Distance 1.6 Dislocations 1.7 Grain Size 1.7.1 Grain Boundaries 1.7.2 Methods of Determining Grain Size 1.7.3 Examples of Grain Size Determinations2 Materials Testing 2.1 The Hardness Test 2.1.1 The Brinell Test 2.1.2 The Vickers Test 2.1.3 The Knoop Test 2.1.4 The Rockwell Test 2.1.5 The Scleroscope Test 2.1.6 Conversion Tables for Various Scales of Hardness 2.2 The Tensile Test 2.2.1 Comparison Between Mechanical Properties Obtained According to Different Specifications 2.3 The Impact Test 2.4 The Torsion Impact Test 2.5 The Fatigue Test 2.5.1 Fatigue in General 2.5.2 Test Procedure 2.5.3 Different Types of Fatigue Fractures 2.5.4 Goodman Diagram 2.5.5 Endurance Limit—Ultimate Tensile Strength 2.5.6 Surface Finish 2.5.7 Influence of Change of Section 2.5.8 Ways of Increasing the Endurance Limit 2.6 The Creep Test 2.7 Brittle and Ductile Fractures 2.8 Fracture Toughness 2.8.1 The Implication of Fracture Toughness3 Alloying Elements in Steel 3.1 Solids 3.1.1 Austenite-Forming Elements 3.1.2 Ferrite-Forming Elements 3.1.3 Multi-Alloyed Steels 3.1.4 Carbide-Forming Elements 3.1.5 Carbide Stabilizers 3.1.6 Nitride-Forming Elements 3.1.7 Effect on Ferrite Hardness 3.1.8 Effect on Grain Growth 3.1.9 Effect on the Eutectoid Point 3.1.10 Effect on the Temperature of Martensite Formation 3.1.11 Effect on the Formation of Pearlite and Bainite during the Isothermal Transformation 3.1.12 Effect on Resistance to Tempering 3.2 Gases 3.2.1 Hydrogen 3.2.2 Nitrogen 3.2.3 Oxygen 3.3 New Steelmaking Processes 3.3.1 Vacuum Remelting 3.3.2 Electroslag Refining 3.3.3 Vacuum Degassing 3.3.4 The Bofors Method of Sulphur Removal 3.3.5 Effect of Sulphur on the Properties of Steel4 Hardenability 4.1 General Remarks 4.2 The Grossmann Hardenability Test 4.2.1 Calculation of Di-Values from Chemical Composition 4.3 The Jominy End-Quench Hardenability Test 4.3.1 Calculation of Jominy Curves from the Chemical Composition 4.3.2 Practical Applications of Jominy Curves 4.4 Practical Application of the TTT and the CCT Diagrams 4.5 Practical Application of Hardenability 4.5.1 High Hardenability 4.5.2 Low Hardenability 4.6 The Influence of the Depth of Hardening on the Stress Pattern5 Heat Treatment—General 5.1 Annealing 5.1.1 Annealing for Maximum Softness or Spheroidizing Anneal 5.1.2 Recrystallization Annealing 5.1.3 Stress-Relief Annealing 5.1.4 Isothermal Annealing 5.1.5 Quench Annealing 5.1.6 Homogenizing Annealing 5.1.7 Hydrogen Annealing 5.1.8 Hydrogen Expulsion 5.2 Normalizing 5.3 Hardening 5.3.1 Heating Media 5.3.2 Rate of Heating 5.3.3 Hardening Temperature 5.3.4 Holding Time at Temperature 5.3.5 Methods of Cooling 5.3.6 Quenching Media 5.3.7 Quenching Equipment 5.4 Tempering 5.4.1 Heating to Temperature 5.4.2 Rate of Heating 5.4.3 Holding Time 5.4.4 Double Tempering 5.4.5 Temper Brittleness 5.5 Transformation of Retained Austenite 5.6 Precipitation Hardening 5.7 Straightening 5.8 Machining Allowances6 Heat Treatment—Special 6.1 Hardening and Tempering of Tool Steels 6.1.1 Carbon Steels and Vanadium-Alloyed Steels 6.1.2 Low-Alloy Cold-Work Steels 6.1.3 Low-Alloy Cold-Work and Hot-Work Steels 6.1.4 High-Alloy Cold-Work Steels 6.1.5 Hot-Work Steels 6.1.6 High-Speed Steels 6.2 Quenching and Tempering of Constructional Steels 6.2.1 Definitions 6.2.2 Plain Carbon Steels 6.2.3 Alloy Steels 6.2.4 Stainless Steels 6.2.5 Spring Steels 6.2.6 High-Strength Steels 6.2.7 Hadfield Steel 6.3 Case Hardening 6.3.1 Definitions 6.3.2 Grades of Steel 6.3.3 Methods of Carburizing 6.3.4 Influence of Heat Treatment and Steel Composition on Case Depth, Surface Hardness and Core Hardness 6.3.5 Recommendations for Case Hardening 6.3.6 Case Hardening of Tool Steels 6.3.7 Protecting Against Carburization (Selective Carburizing) 6.3.8 Choice of Case-Hardening Depth 6.4 Nitriding 6.4.1 Methods of Nitriding 6.4.2 Comparison Between Gas and Salt-Bath Nitriding 6.4.3 Nitridability 6.4.4 Determination of Depth of Nitriding 6.4.5 Nitriding Different Types of Steel 6.4.6 Properties of Nitrided Steels 6.5 Carbonitriding 6.5.1 Definition 6.5.2 Theoretical Background 6.5.3 Conclusions 6.6 Induction Hardening 6.6.1 Fundamental Principles 6.6.2 Steel Grades for Induction Hardening 6.6.3 Equipment for Induction Hardening 6.6.4 Working Coils and Fixtures 6.6.5 Procedure During Induction Hardening 6.6.6 The Influence of Various Factors on Hardness and Depth of Hardening 6.6.7 Examples of Induction-Hardened Machine Components 6.6.8 Advantages and Disadvantages of Induction Hardening 6.7 Flame Hardening 6.7.1 Methods of Hardening 6.7.2 Hardness and Depth of Hardening 6.7.3 Examples of Flame-Hardened Machine Components and Tools7 Dimensional Changes during Hardening and Tempering 7.1 Dimensional Changes during Hardening 7.1.1 Thermal Stresses 7.1.2 Transformation Stresses 7.2 Dimensional Changes during Tempering 7.2.1 Changes in Volume 7.2.2 Changes in Stress Conditions 7.3 Examples of Dimensional Changes during the Hardening and Tempering of Tool Steels 7.3.1 Plain Carbon Steels 7.3.2 Low-Alloy Steels 7.3.3 High-Alloy Cold-Work Steels 7.3.4 Hot-Work Steels 7.3.5 High-Speed Steels 7.4 Dimensional Changes during Case Hardening 7.5 Dimensional Changes during Nitriding 7.6 Ageing 7.7 Designing for Heat Treatment8 Tables 8.1 Some Steel Standard Specifications and Comparable Bofors and Uddeholm (UHB) Steels Table 8.1 American Steel Standard Specifications Table 8.2 British Steel Standard Specifications Table 8.3 German Steel Standard Specifications Table 8.4 Swedish Steel Standard Specifications Table 8.5 Afnor Designations (French) Table 8.6 ASSAB Designations (Associated Swedish Steels AB) 8.2 Weight Tables for Steel Bars Table 8.7 Round and Square Bars. Metric Units Table 8.8 Hexagonal and Octagonal Bars. Metric Units Table 8.9 Flat Bars, 10 to 40 mm. Metric Units Table 8.10 Flat Bars, 45 to 130 mm. Metric Units Table 8.11 Flat Bars, 140 to 350 mm. Metric Units Table 8.12 Round and Square Bars. Inch Units Table 8.13 Hexagonal and Octagonal Bars. Inch Units Table 8.14 Flat Bars, Width 3/8 to 1/2 in. Inch Units Table 8.15 Flat Bars, Width 1 5/8 to 5 in. Inch Units Table 8.16 Flat Bars, Width 5 1/2 to 15 in. Inch Units 8.3 Conversion Tables for Temperature Table 8.17 Conversion Table for °Celsius (Centigrade) and °Fahrenheit 8.4 Conversion Table for Size Table 8.18 Inches to Millimetres Table 8.19 Decimals of Inches to Millimetres 8.5 Conversion Tables for Weight (Mass) Table 8.20 Pounds to Kilogrammes Table 8.21 British Units to Kilogrammes 8.6 Conversion Table for Stress (Pressure) Table 8.22 Tons Per Square Inch to Kiloponds Per Square Millimetre Table 8.23 Tons Per Square Inch to Newtons Per Square Millimetre Table 8.24 Kiloponds Per Square Millimetre to Newtons Per Square Millimetre Table 8.25 Pounds Per Square Inch to Kiloponds Per Square Millimetre 8.7 Conversion Tables for Energy Table 8.26 Kilopond Metres to Footpounds Table 8.27 Footpounds to Kilopond Metres Table 8.28 Kilopond Metres to Joules Table 8.29 Footpounds to Joules 8.8 Conversion Table for Fracture Toughness Units Table 8.30 Fracture Toughness Units 8.9 Conversions for Some Common Units Table 8.31 Common SI Units to British Units Table 8.32 Common Non-SI Units to British Units Table 8.33 Non-SI Metric Units to SI Units 8.10 Elements Table 8.34 Atomic Number and Atomic WeightIndex