A Practical Guide to Welding Solutions

Preface xi 1 Introduction 1 Further Reading 6 2 Categorization of Welding and Weld Problems 7 2.1 What Is Welding? 7 2.2 Microstructural Zones of Welds 13 2.3 Origin of Problems in Welding and Welds 19 2.4 How Problems Can Be Logically Categorized? 20 References 21 Further Reading 21 Part I Manifestation of Problems with Welds and Weldments 23 3 Problems with Joint Setup and Weld Joints 25 3.1 Joint Efficiency 25 3.2 Weld Joint Types and Weld Configurations 26 3.3 Joint Setup Problems 31 3.4 Problems with Weld Profile 35 3.5 Troubleshooting Guide 42 References 45 Further Reading 45 4 Shape Distortion, Dimensional Shrinkage, and Geometric Instability 47 4.1 Thermal Versus Mechanical Stresses in a Structure 47 4.2 Residual Stresses Versus Distortion 48 4.3 Origin and Effect of Volumetric Shrinkage 48 4.4 Origin and Effect of Thermal Contraction 52 4.5 Problems from Nonuniform Thermal Contraction and CTE Mismatches 57 4.6 Problems from Distortion and from Residual Stresses 60 4.7 Distortion Control and Residual Stress Reduction 60 4.8 Troubleshooting Guide 65 References 65 Further Reading 66 5 Porosity 67 5.1 The Most Common Problem in Welds 67 5.2 Types of Weld Porosity 70 5.3 Gases in Molten Weld Metal 73 5.4 The Many Possible Causes of Porosity in Welds 79 5.5 Attempting to Minimize Porosity Formation in Fusion Welds 84 5.6 Troubleshooting Porosity Problems in Welds 85 References 87 Further Reading 87 6 Cracks 89 6.1 The Most Dreaded Defect in Welds 89 6.2 Classification of Cracking and Cracks in Welds and Welding 90 6.3 Hot Cracking and Cracks 91 6.4 Cold Cracking and Cracks 98 6.5 Other Weld-Related Cracking and Cracks 101 6.6 Crack-Prone Metals and Alloys 102 6.7 Troubleshooting Cracking Problems in Welds 105 References 106 Further Reading 107 7 Nonmetallic and Metallic Inclusions 109 7.1 Solid Versus Gas Inclusions 109 7.2 Nonmetallic Inclusions in Welds 110 7.3 Metallic Inclusions in Welds 114 7.4 Troubleshooting Problems with Inclusions in Welds 115 References 116 Further Reading 116 8 Weld Appearance 117 8.1 Can You Judge a Book by Its Cover? Is Beauty Only Skin Deep? 117 8.2 Weld Crown Bead Faults 118 8.3 Weld Root Bead Faults 121 8.4 Fillet Weld Faults 123 8.5 Reading Weld Ripple Marks 124 8.6 Weld Spatter 126 8.7 Arc Strikes 128 8.8 Weld Heat Tint 129 8.9 Troubleshooting Weld Appearance Problems 132 References 133 Further Reading 134 Part II Location of Problems in Welds 135 9 Fusion Zone of Fusion Welds 137 9.1 A Refresher on Microstructural Zones in and Around Welds 137 9.2 Gas Porosity in the Fusion Zone of Welds 141 9.3 Cracking in the Fusion Zone of Welds 143 9.4 Inclusions in the Fusion Zone of Welds 151 9.5 Macrosegregation in the Fusion Zone of Welds 152 9.6 Troubleshooting Problems in the Fusion Zone of Welds 153 References 155 Further Reading 156 10 Partially Melted Zone of Fusion Welds 157 10.1 Origin and Location of the PMZ in Fusion Welds 157 10.2 Conventional Hot Cracking in the PMZ 161 10.3 Constitutional Liquation Cracking in the PMZ 161 10.4 Cold Cracking in the PMZ 164 10.5 Overcoming Cracking Problems in the PMZ 166 10.6 Troubleshooting Problems in the PMZ 167 References 167 Further Reading 168 11 Heat-Affected Zone of Fusion Welds 169 11.1 Origin and Location of the HAZ for Fusion Welds 169 11.2 Manifestation of Problems in the HAZ of Fusion Welds 170 11.3 Precipitation-Hardening Alloy HAZ Problems 171 11.4 Sensitization in the HAZ of Austenitic Stainless Steels 176 11.5 Transformation-Hardening Steel HAZ Problems 179 11.6 Reheat Cracking 183 11.7 Troubleshooting Problems in the HAZ of Fusion Welds 186 References 187 Further Reading 188 12 Unaffected Base Metal Cracking Associated with Welding 189 12.1 Weld-Related Problems in the Unaffected Base Metal 189 12.2 Lamellar Tearing in Thick Steel Weldments 189 12.3 Corrosion Cracking Caused by Fusion Welding 192 12.4 Fatigue Cracking Outside Fusion Welds 195 12.5 Troubleshooting Weld-Related Problems in the Unaffected Base Metal 199 References 200 Further Reading 201 13 Discontinuities in Multi-pass Welds 203 13.1 Needs for Multi-pass Welding and Welds 203 13.2 Various Functions of Multi-pass Welding and Welds 205 13.3 Defects Found in Multi-pass Welds 207 13.4 Composition Adjustment with Multi-pass Welding 210 13.5 Property Alteration with Multi-pass Welding 213 13.6 Troubleshooting Problems in Multi-pass Welding and Welds 216 References 217 Further Reading 217 14 Problems with Non-fusion Welding and Non-fusion Welds 219 14.1 Non-fusion Welding Processes Versus Fusion Welding Processes 219 14.2 Overview of Non-fusion Processes 220 14.2.1 Pressure Welding Processes 222 14.2.2 Friction Welding Processes 222 14.2.3 Diffusion Welding Processes 222 14.2.4 Solid-State Deposition Welding 223 14.3 Problems with Non-fusion Welds and Non-fusion Welding Processes 223 14.4 Inspection and Repair Challenges with Non-fusion Welds 229 14.5 Troubleshooting Problems with Non-fusion Welds 230 References 230 Further Reading 231 Part III Material-Specific Weld-Related Problems 233 15 Embrittlement of Carbon and Low- and Medium-alloy Steels 235 15.1 The Importance of Steel 235 15.2 Four Causes of Embrittlement in Carbon and Low- and Medium-alloy Steels 238 15.3 Hydrogen Embrittlement: A Misnomer in Steels 239 15.4 Secondary Hardening in Steels 240 15.5 Ductile-to-Brittle Transition in Steels 241 15.6 Compromise of Fatigue and Impact Behavior by Residual Stresses in Steels 243 15.7 Troubleshooting Problems from Embrittlement of Steels by Welding 244 References 245 Further Reading 245 16 Sensitization or Weld Decay and Knife-line Attack in Stainless Steels 247 16.1 A Primer on the Metallurgy of Stainless Steels 247 16.2 Sensitization of Austenitic Stainless Steels by Welding 249 16.3 Sensitization of Other Grades of Stainless Steel 252 16.4 Knife-line Attack in Stabilized Austenitic Stainless Steels 252 16.5 Troubleshooting Problems from Sensitization or Knife-line Attack 254 References 255 Further Reading 255 17 Stress Relief Cracking of Precipitation-Hardening Alloys 257 17.1 Different Names, Same Phenomenon 257 17.2 Stress Relief Cracking in Ferritic Alloy Steels 260 17.3 Stress Relaxation Cracking in Stainless Steels 265 17.4 Strain-age Cracking in Ni-Based Superalloys 267 17.5 Troubleshooting Problems from Stress Relief or Strain-age Cracking 270 References 271 Further Reading 271 18 Loss of Properties in Cold-Worked Metals and Alloys 273 18.1 Cold Work, Recovery, Recrystallization, and Grain Growth 273 18.2 Cold-Worked Metals and Alloys in Engineering 278 18.3 Avoiding or Recovering Properties Loss from Fusion Welding 281 18.4 The Worked Zone in Pressure-Welded Metals and Alloys 284 18.5 Troubleshooting Welding Problems in Cold-Worked Metals and Alloys 285 References 285 Further Reading 286 19 Embrittlement with High-chromium Contents 287 19.1 Phase Formation and Structure 287 19.2 Adverse Effects of σ-Phase 291 19.3 Susceptible Alloys 291 19.4 Guidelines for Avoiding or Resolving Problems from σ-Phase 293 19.5 Troubleshooting Problems with σ-Phase Associated with Welding 294 References 295 Further Reading 295 20 Weld Dilution and Chemical Inhomogeneity 297 20.1 The Designer’s Druthers 297 20.2 Chemical Inhomogeneity in Welds 300 20.3 Weld Dilution 302 20.4 The Unmixed Zone in the Weld Metal 304 20.5 Impurities in the Weld Metal 307 20.6 Troubleshooting Problems from Weld Dilution and Chemical Inhomogeneity 307 References 308 Further Reading 308 21 Dissimilar Metal and Alloy Welding 309 21.1 Joining Dissimilar Materials 309 21.2 The Need for Welding Dissimilar Metals and Alloys 311 21.3 Chemical Incompatibility 311 21.4 Mechanical Incompatibility 315 21.5 Thermal Incompatibility 315 21.6 Troubleshooting Problems with Dissimilar Metal and Alloy Welding 318 References 318 Further Reading 319 Closing Thoughts 321 Index 323