معى اليوم احبتى فى الله
PRINCIPLES OF
WELDING
Processes, Physics, Chemistry,
and Metallurgy
CONTENTS
PREFACE xix
I THE PROCESS AND PROCESSES OF WELDING
1 INTRODUCTION TO THE PROCESS OF WELDING
1.1 What Is Welding? / 3
1.2 The Evolution of Welding as a Process / 6
1.3 The Nature of an Ideal Weld: Achieving Continuity / 7
1.4 Impediments to Making Ideal Welds in the Real World / 10
1.5 What It Takes to Make a Real Weld / 12
1.6 Advantages and Disadvantages of Welding / 14
1.7 Summary / 15
References and Suggested Reading / 15
2 CLASSIFYING WELDING PROCESSES
2.1
2.2
2.3
2.4
Why Classify Processes? / 17
Mechanisms for Obtaining Material Continuity / 18
The Roles of Temperature and Pressure / 21
Alternative Bases for Classification / 23
2.4.1 Fusion Versus Nonfusion / 23
2.4.2 Pressure Versus Nonpressure / 25
2.4.3 Energy Source for Welding / 25
2.4.4 Interface Relationships and Classification by Energy
Transfer Processes / 27
2.4.5 Other Bases for Classification and Subclassification / 28
2.5 Allied Processes / 35
2.6 The AWS Classification Scheme / 37
2.7 Summary / 39
References and Suggested Reading / 39
3 FUSION WELDING PROCESSES 40
3.1 General Description of Fusion Welding Processes / 40
3.2 Chemical Fusion Welding Processes / 41
3.2.1 Oxyfuel Gas Welding / 41
3.2.2 Aluminothermic Welding / 46
3.3 Electric Arc Welding Processes / 49
3.3.1 Nonconsumable Electrode Arc Welding Processes / 50
3.3.1.1 Gas-Tungsten Arc Welding / 51
3.3.1.2 Plasma Arc Welding / 55
3.3.1.3 Magnetically Impelled Arc Butt Welding 1' 57
3.3.2 Consumable Electrode Arc Welding Processes / 60
3.3.2.1 Gas-Metal Arc Welding / 60
3.3.2.2 Shielded-Metal Arc Welding / 64
3.3.2.3 Flux-Cored Arc Welding / 66
3.3.2.4 Submerged Arc Welding / 68
3.3.2.5 Electrogas Welding / 69
3.3.2.6 Electroslag Welding / 70
3.4 Resistance Welding Processes / 71
3.4.1 Resistance Spot, Resistance Seam, and Projection
Welding / 71
3.4.2 Flash, Upset, and Percussion Welding / 74
3.5 High-Intensity Radiant Energy or High-Density Beam
Welding Processes / 77
3.5.1 High-Energy-Density (Laser and Electron) Beam
Welding Processes / 80
3.5.2 Focused IR and Imaged Arc Welding / 86
3.5.3 Microwave Welding / 88
References and Suggested Reading / 93
4 NONFUSION WELDING PROCESSES 94
4.1 General Description of Nonfusion Welding Processes / 94
4.2 Pressure (Nonfusion) Welding Processes / 97
4.2.1 Cold Welding Processes / 98
4.2.2 Hot Pressure Welding / 99
4.2.2.1
4.2.2.2 Forge Welding / 101
Pressure Gas Welding / 100
4.2.3 Roll Welding / 102
4.2.4 Explosion Welding / 103
4.3 Friction Welding Processes / 105
4.3.1 Radial and Orbital Welding / 107
4.3.2 Direct-Drive Versus Inertia-Drive (Friction)
Welding / 107
4.3.3 Angular and Linear Reciprocating (Friction)
Welding / 108
4.3.4 Ultrasonic (Friction) Welding / 109
4.3.5 Friction Stir Welding / 112
4.3.6 Friction Surfacing / 113
4.4 Diffusion Joining Processes / 113
4.4.1 Diffusion Welding / 114
4.4.1.1 Conventional Diffusion Welding / 118
4.4.1.2 Deformation Diffusion Welding / 118
4.4.1.3 Resistance Diffusion Welding / 118
4.4.1.4 Continuous Seam Diffusion Welding / 118
4.4.2 Diffusion Brazing / 119
4.4.3 Combined Forming and Diffusion Welding / 119
4.5 Solid-state Deposition Welding Processes / 120
4.6 Inspection and Repair of Nonfusion Welds / 120
4.7 Summary / 123
References and Suggested Reading / 123
IJ THE PHYSICS OF WELDING
5 ENERGY FOR WELDING
5.1 Introduction to the Physics of Welding / 127
5.2 Sources of Energy for Welding / 127
127
5.3
5.4
5.5
5.6
5.7
5.8
5.9
Source Energy, Transferred Power, Energy Density,
and Energy Distribution / 128
5.3.1 Energy Available at a Source (Energy Level
or Capacity / 128
5.3.2 Transferred Power / 130
5.3.3 Source Intensity or Energy Density / 130
5.3.4 Energy Distribution / 131
Energy Input to a Weld / 132
Causes of Loss During Energy Transfer From Source
to Work / 134
Transfer Efficiency of Processes / 134
Effects of Deposited Energy: Good and Bad / 138
5.7.1 Desirable Melting, Fluxing, or Softening / 139
5.7.2 Adverse Effects of Heat in and Around the Weld / 141
Effects of Energy Density and Distribution / 142
Summary / 144
References and Suggested Reading / 146
6 THE FLOW OF HEAT IN WELDS 147
6.1
6.2
6.3
6.4
6.5
6.6
6.7
General Description of the Flow of Heat in Welds / 147
Weld Joint Configurations / 148
6.2.1 Types of Weld Joints / 148
6.2.2 General Weld Design Guidelines / 152
6.2.3 Size of a Weld and Amount of Welding / 154
The Welding Thermal Cycle / 154
The Generalized Equation of Heat Flow / 158
Analysis of Heat Flow During Welding / 161
6.5.1 Rosenthal's Simplified Approach / 162
6.5.2 Modifications to Rosenthal's Solutions / 165
6.5.3 Dimensionless Weld Depth Versus Dimensionless
Operating Parameter / 167
Effect of Welding Parameters on Heat Distribution / 168
Prediction of Weld Zones and Weld Cooling Rates / 172
6.7.1 Zones in Fusion-Welded Materials / 172
6.7.2 Simplified Equations for Approximating Welding
Conditions / 173
6.7.2.1 Peak Temperatures / 174
6.7.2.2 Width of the Heat-Affected Zone / 174
6.7.2.3 Solidification Rate / 174
6.7.2.4 Cooling Rates / 1756.8 Weld Simulation and Simulators / 176
6.9 Summary / 178
References and Suggested Reading / 178
7 THERMALLY INDUCED DISTORTION AND RESIDUAL
STRESSES DURING WELDING 181
7.1 Origin of Thermal Stresses / 181
7.2 Distortion Versus Residual Stresses / 183
7.2.1 Causes of Residual Stresses in Weldments / 185
7.2.1.1 Residual Stresses From Mismatch / 186
7.2.1.2 Residual Stresses From Nonuniform,
Nonelastic Strains / 189
7.2.2 Causes of Distortion in Weldments / 190
7.3 Typical Residual Stresses in Weldments / 191
7.4 Effects of Distortion / 194
7.5 Effects of Residual Stresses / 196
7.6 Measurement of Residual Stresses in Weldments / 197
7.6.1 Stress-Relaxation Techniques / 199
7.6.1.1 A Sectioning Technique Using Electric-Resistance
Strain Gauges / 199
7.6.1.2 The Rosenthal-Norton Section Technique / 201
7.6.1.3 The Mathar-Soete Hole Drilling Technique / 202
7.6.1.4 The Gunnert Drilling Technique / 202
7.6.2 The X-ray Diffraction Technique / 204
7.7 Residual Stress Reduction and Distortion Control / 206
7.7.1 The Interplay Between Residual Stresses and
Distortion / 206
7.7.2 Prevention Versus Remediation / 206
7.7.3 Controlling or Removing Residual Stresses / 207
7.7.4 Controlling or Removing Distortion / 208
7.8 Numerical Methods for Estimating Residual Stresses / 210
7.9 Summary / 211
References and Suggested Reading / 214
8 THE PHYSICS OF WELDING ENERGY OR POWER
SOURCES
8.1 Electricity for Welding / 216
8.2 The Physics of an Electric Arc and Arc Welding / 223
8.2.1 The Physics of an Electric Arc / 2238.2.1.1 The Welding Arc / 224
8.2.1.2 The Arc Plasma / 224
8.2.1.3 Arc Temperature / 224
8.2.1.4 Arc Radiation / 226
8.2.1.5 Arc Electrical Features / 226
8.2.1.6 Effect of Magnetic Fields on Arcs / 228
8.2.2 Volt-Ampere Characteristics for Welding / 231
8.2.2.1 Constant-Current Power Sources / 232
8.2.2.2 Constant-Voltage Power Sources / 232
8.2.2.3 Combined Characteristic Sources / 234
8.3 The Physics of a Plasma / 234
8.4 The Physics of Resistance (or Joule) Heating and
Resistance Welding / 237
8.4.1 Joule Heating / 237
8.4.2 The Resistance Welding Cycle / 239
8.4.3 Resistance Welding Power Supplies / 239
8.5 The Physics of Electron Beams / 243
8.5.1 Electron-Beam Generation / 245
8.5.2 Electron-Beam Control / 248
8.5.3 Role of Vacuum in EB Welding / 252
8.5.4 Electron-Beam-Material Interactions / 253
8.6 The Physics of Laser Beams / 256
8.6.1 Laser Light / 256
8.6.2 Laser Generation / 256
8.6.2.1 Nd:YAG Lasers / 258
8.6.2.2 CO, Lasers / 259
8.6.3 Laser-Beam Control / 259
8.6.4 Laser-Beam-Material Interactions / 260
8.6.5 Benefits of Laser-Beam and Electron-Beam Welding / 263
8.7 The Physics of a Combustion Flame / 265
8.7.1 Fuel Gas Combustion or Heat of Combustion / 265
8.7.2 Flame Temperature / 265
8.7.3 Flame Propagation Rate or Combustion Velocity / 266
8.7.4 Combustion Intensity / 266
8.8 The Physics of Converting Mechanical Work to Heat / 266
8.9 Summary / 268
References and Suggested Reading J 269
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