Details

<p>Preface to Third Edition xxi</p> <p><b>Part I Introduction 1</b></p> <p><b>1 Welding Processes </b><b>3</b></p> <p>1.1 Overview 3</p> <p>1.1.1 Fusion Welding Processes 3</p> <p>1.1.1.1 Power Density of Heat Source 4</p> <p>1.1.1.2 Welding Processes and Materials 5</p> <p>1.1.1.3 Types of Joints and Welding Positions 7</p> <p>1.1.2 Solid-State Welding Processes 8</p> <p>1.2 Gas Welding 8</p> <p>1.2.1 The Process 8</p> <p>1.2.2 Three Types of Flames 9</p> <p>1.2.2.1 Neutral Flame 9</p> <p>1.2.2.2 Reducing Flame 9</p> <p>1.2.2.3 Oxidizing Flame 9</p> <p>1.2.3 Advantages and Disadvantages 10</p> <p>1.3 Arc Welding 10</p> <p>1.3.1 Shielded Metal Arc Welding 10</p> <p>1.3.1.1 Functions of Electrode Covering 10</p> <p>1.3.1.2 Advantages and Disadvantages 11</p> <p>1.3.2 Gas–Tungsten Arc Welding 11</p> <p>1.3.2.1 The Process 11</p> <p>1.3.2.2 Polarity 12</p> <p>1.3.2.3 Electrodes 13</p> <p>1.3.2.4 Shielding Gases 13</p> <p>1.3.2.5 Advantages and Disadvantages 13</p> <p>1.3.3 Plasma Arc Welding 14</p> <p>1.3.3.1 The Process 14</p> <p>1.3.3.2 Arc Initiation 14</p> <p>1.3.3.3 Keyholing 15</p> <p>1.3.3.4 Advantages and Disadvantages 15</p> <p>1.3.4 Gas–Metal Arc Welding 16</p> <p>1.3.4.1 The Process 16</p> <p>1.3.4.2 Shielding Gases 16</p> <p>1.3.4.3 Modes of Metal Transfer 17</p> <p>1.3.4.4 Advantages and Disadvantages 18</p> <p>1.3.5 Flux-Cored Arc Welding 18</p> <p>1.3.5.1 The Process 18</p> <p>1.3.6 Submerged Arc Welding 19</p> <p>1.3.6.1 The Process 19</p> <p>1.3.6.2 Advantages and Disadvantages 20</p> <p>1.3.7 Electroslag Welding 20</p> <p>1.3.7.1 The Process 20</p> <p>1.3.7.2 Advantages and Disadvantages 21</p> <p>1.4 High-Energy-Beam Welding 21</p> <p>1.4.1 Electron Beam Welding 21</p> <p>1.4.1.1 The Process 21</p> <p>1.4.1.2 Advantages and Disadvantages 23</p> <p>1.4.2 Laser Beam Welding 24</p> <p>1.4.2.1 The Process 24</p> <p>1.4.2.2 Reflectivity 24</p> <p>1.4.2.3 Shielding Gas 25</p> <p>1.4.2.4 Laser-Assisted Arc Welding 25</p> <p>1.4.2.5 Advantages and Disadvantages 26</p> <p>1.5 Resistance Spot Welding 26</p> <p>1.6 Solid-State Welding 27</p> <p>1.6.1 Friction Stir Welding 27</p> <p>1.6.2 Friction Welding 29</p> <p>1.6.3 Explosion and Magnetic-Pulse Welding 31</p> <p>1.6.4 Diffusion Welding 31</p> <p>Examples 32</p> <p>References 33</p> <p>Further Reading 34</p> <p>Problems 35</p> <p><b>2 Heat Flow in Welding </b><b>37</b></p> <p>2.1 Heat Source 37</p> <p>2.1.1 Heat Source Efficiency 37</p> <p>2.1.1.1 Definition 37</p> <p>2.1.1.2 Measurements 38</p> <p>2.1.1.3 Heat Source Efficiencies in Various Welding Processes 41</p> <p>2.1.2 Melting Efficiency 42</p> <p>2.1.3 Power Density Distribution of Heat Source 43</p> <p>2.1.3.1 Effect of Electrode Tip Angle 43</p> <p>2.1.3.2 Measurements 43</p> <p>2.2 Heat Flow During Welding 45</p> <p>2.2.1 Response of Material to Welding Heat Source 45</p> <p>2.2.2 Rosenthal’s Equations 45</p> <p>2.2.2.1 Rosenthal’s Two-Dimensional Equation 46</p> <p>2.2.2.2 Rosenthal’s Three-Dimensional Equation 47</p> <p>2.2.2.3 Step-by-Step Application of Rosenthal’s Equations 48</p> <p>2.2.3 Adams’ Equations 49</p> <p>2.3 Effect of Welding Conditions 49</p> <p>2.4 Computer Simulation 52</p> <p>2.5 Weld Thermal Simulator 53</p> <p>2.5.1 The Equipment 53</p> <p>2.5.2 Applications 54</p> <p>2.5.3 Limitations 54</p> <p>Examples 54</p> <p>References 57</p> <p>Further Reading 59</p> <p>Problems 59</p> <p><b>3 Fluid Flow in Welding </b><b>61</b></p> <p>3.1 Fluid Flow in Arcs 61</p> <p>3.1.1 Sharp Electrode 61</p> <p>3.1.2 Flat-End Electrode 63</p> <p>3.2 Effect of Metal Vapor on Arcs 63</p> <p>3.2.1 Gas−Tungsten Arc Welding 63</p> <p>3.2.2 Gas−Metal Arc Welding 65</p> <p>3.3 Arc Power- and Current-Density Distributions 68</p> <p>3.4 Fluid Flow in Weld Pools 69</p> <p>3.4.1 Driving Forces for Fluid Flow 69</p> <p>3.4.2 Heiple’s Theory for Weld Pool Convection 71</p> <p>3.4.3 Physical Simulation of Fluid Flow and Weld Penetration 72</p> <p>3.4.4 Computer Simulation of Fluid Flow and Weld Penetration 75</p> <p>3.5 Flow Oscillation and Ripple Formation 77</p> <p>3.6 Active Flux GTAW 80</p> <p>3.7 Resistance Spot Welding 81</p> <p>Examples 84</p> <p>References 85</p> <p>Further Reading 88</p> <p>Problems 88</p> <p><b>4 Mass and Filler</b><b>–Metal Transfer 91</b></p> <p>4.1 Convective Mass Transfer in Weld Pools 91</p> <p>4.2 Evaporation of Volatile Solutes 94</p> <p>4.3 Filler-Metal Drop Explosion and Spatter 96</p> <p>4.4 Spatter in GMAW of Magnesium 100</p> <p>4.5 Diffusion Bonding 100</p> <p>Examples 103</p> <p>References 104</p> <p>Problems 105</p> <p><b>5 Chemical Reactions in Welding </b><b>107</b></p> <p>5.1 Overview 107</p> <p>5.1.1 Effect of Nitrogen, Oxygen, and Hydrogen 107</p> <p>5.1.2 Protection Against Air 107</p> <p>5.1.3 Evaluation of Weld Metal Properties 108</p> <p>5.2 Gas–Metal Reactions 111</p> <p>5.2.1 Thermodynamics of Reactions 111</p> <p>5.2.2 Hydrogen 113</p> <p>5.2.2.1 Magnesium 113</p> <p>5.2.2.2 Aluminum 113</p> <p>5.2.2.3 Titanium 116</p> <p>5.2.2.4 Copper 116</p> <p>5.2.2.5 Steels 116</p> <p>5.2.3 Nitrogen 118</p> <p>5.2.3.1 Steel 118</p> <p>5.2.3.2 Titanium 121</p> <p>5.2.4 Oxygen 121</p> <p>5.2.4.1 Magnesium 121</p> <p>5.2.4.2 Aluminum 121</p> <p>5.2.4.3 Titanium 121</p> <p>5.2.4.4 Steel 122</p> <p>5.3 Slag–Metal Reactions 125</p> <p>5.3.1 Thermochemical Reactions 125</p> <p>5.3.1.1 Decomposition of Flux 125</p> <p>5.3.1.2 Removal of S and P from Liquid Steel 126</p> <p>5.3.2 Effect of Flux on Weld Metal Oxygen 127</p> <p>5.3.3 Types of Fluxes, Basicity Index, and Weld Metal Properties 127</p> <p>5.3.4 Basicity Index 128</p> <p>5.3.5 Electrochemical Reactions 130</p> <p>Examples 135</p> <p>References 136</p> <p>Further Reading 140</p> <p>Problems 140</p> <p><b>6 Residual Stresses, Distortion, and Fatigue </b><b>141</b></p> <p>6.1 Residual Stresses 141</p> <p>6.1.1 Development of Residual Stresses 141</p> <p>6.1.1.1 Stresses Induced By Welding 141</p> <p>6.1.1.2 Welding 141</p> <p>6.1.2 Analysis of Residual Stresses 143</p> <p>6.2 Distortion 145</p> <p>6.2.1 Cause 145</p> <p>6.2.2 Remedies 146</p> <p>6.3 Fatigue 147</p> <p>6.3.1 Mechanism 147</p> <p>6.3.2 Fractography 147</p> <p>6.3.3 S–N Curves 150</p> <p>6.3.4 Effect of Joint Geometry 150</p> <p>6.3.5 Effect of Stress Raisers 151</p> <p>6.3.6 Effect of Corrosion 152</p> <p>6.3.7 Remedies 152</p> <p>6.3.7.1 Shot Peening 152</p> <p>6.3.7.2 Reducing Stress Raisers 153</p> <p>6.3.7.3 Laser Shock Peening 154</p> <p>6.3.7.4 Use of Low–Transformation–Temperature Fillers 154</p> <p>Examples 154</p> <p>References 155</p> <p>Further Reading 156</p> <p>Problems 156</p> <p><b>Part II The Fusion Zone 157</b></p> <p><b>7 Introduction to Solidification </b><b>159</b></p> <p>7.1 Solute Redistribution During Solidification 159</p> <p>7.1.1 Directional Solidification 159</p> <p>7.1.2 Equilibrium Segregation Coefficient <i>k </i>159</p> <p>7.1.3 Four Cases of Solute Redistribution 161</p> <p>7.2 Constitutional Supercooling 166</p> <p>7.3 Solidification Modes 168</p> <p>7.4 Microsegregation Caused by Solute Redistribution 171</p> <p>7.5 Secondary Dendrite Arm Spacing 174</p> <p>7.6 Effect of Dendrite Tip Undercooling 177</p> <p>7.7 Effect of Growth Rate 178</p> <p>7.8 Solidification of Ternary Alloys 178</p> <p>7.8.1 Liquidus Projection 178</p> <p>7.8.2 Solidification Path 179</p> <p>7.8.3 Ternary Magnesium Alloys 180</p> <p>7.8.4 Ternary Fe-Cr-Ni Alloys 182</p> <p>7.8.4.1 Fe-Cr-Ni Phase Diagram 182</p> <p>7.8.4.2 Solidification Paths 185</p> <p>7.8.4.3 Microstructure 186</p> <p>Examples 189</p> <p>References 191</p> <p>Further Reading 193</p> <p>Problems 193</p> <p><b>8 Solidification Modes </b><b>195</b></p> <p>8.1 Solidification Modes 195</p> <p>8.1.1 Temperature Gradient and Growth Rate 195</p> <p>8.1.2 Variations in Growth Mode Across Weld 197</p> <p>8.2 Dendrite Spacing and Cell Spacing 200</p> <p>8.3 Effect of Welding Parameters 201</p> <p>8.3.1 Solidification Mode 201</p> <p>8.3.2 Dendrite and Cell Spacing 202</p> <p>8.4 Refining Microstructure Within Grains 203</p> <p>8.4.1 Arc Oscillation 203</p> <p>8.4.2 Arc Pulsation 205</p> <p>Examples 205</p> <p>References 206</p> <p>Further Reading 207</p> <p>Problems 207</p> <p><b>9 Nucleation and Growth of Grains </b><b>209</b></p> <p>9.1 Epitaxial Growth at the Fusion Line 209</p> <p>9.2 Nonepitaxial Growth at the Fusion Line 212</p> <p>9.2.1 Mismatching Crystal Structures 212</p> <p>9.2.2 Nondendritic Equiaxed Grains 213</p> <p>9.3 Growth of Columnar Grains 214</p> <p>9.4 Effect of Welding Parameters on Columnar Grains 215</p> <p>9.5 Control of Columnar Grains 218</p> <p>9.6 Nucleation Mechanisms of Equiaxed Grains 219</p> <p>9.6.1 Microstructure Around Pool Boundary 219</p> <p>9.6.2 Dendrite Fragmentation 220</p> <p>9.6.3 Grain Detachment 222</p> <p>9.6.4 Heterogeneous Nucleation 222</p> <p>9.6.5 Effect of Welding Parameters on Heterogeneous Nucleation 225</p> <p>9.6.6 Surface Nucleation 228</p> <p>9.7 Grain Refining 228</p> <p>9.7.1 Inoculation 228</p> <p>9.7.2 Weld Pool Stirring 229</p> <p>9.7.2.1 Magnetic Weld Pool Stirring 229</p> <p>9.7.2.2 Ultrasonic Weld Pool Stirring 229</p> <p>9.7.3 Arc Pulsation 232</p> <p>9.7.4 Arc Oscillation 232</p> <p>9.8 Identifying Grain-Refining Mechanisms 233</p> <p>9.8.1 Overlap Welding Procedure 233</p> <p>9.8.2 Identifying the Grain-Refining Mechanism 235</p> <p>9.8.3 Effect of Arc Oscillation on Dendrite Fragmentation 236</p> <p>9.8.4 Effect of Arc Oscillation on Constitutional Supercooling 236</p> <p>9.8.5 Effect of Composition on Grain Refining by Arc Oscillation 238</p> <p>9.9 Grain-Boundary Migration 238</p> <p>Examples 239</p> <p>References 240</p> <p>Further Reading 245</p> <p>Problems 246</p> <p><b>10 Microsegregation </b><b>247</b></p> <p>10.1 Microsegregation in Welds 247</p> <p>10.2 Effect of Travel Speed on Microsegregation 249</p> <p>10.3 Effect of Primary Solidification Phase on Microsegregation 252</p> <p>10.4 Effect of Maximum Solid Solubility on Microsegregation 253</p> <p>Examples 259</p> <p>References 261</p> <p>Further Reading 262</p> <p>Problems 262</p> <p><b>11 Macrosegregation </b><b>263</b></p> <p>11.1 Macrosegregation in the Fusion Zone 263</p> <p>11.2 Quick Freezing of One Liquid Metal in Another 265</p> <p>11.3 Macrosegregation in Dissimilar-Filler Welding 265</p> <p>11.3.1 Bulk Weld-Metal Composition 265</p> <p>11.3.2 Mechanism I 267</p> <p>11.3.3 Mechanism II 270</p> <p>11.4 Macrosegregation in Dissimilar-Metal Welding 279</p> <p>11.4.1 Mechanism I 279</p> <p>11.4.2 Mechanism II 283</p> <p>11.5 Reduction of Macrosegregation 286</p> <p>11.6 Macrosegregation in Multiple-Pass Welds 287</p> <p>References 290</p> <p>Further Reading 291</p> <p>Problems 291</p> <p><b>12 Some Alloy-Specific Microstructures and Properties </b><b>293</b></p> <p>12.1 Austenitic Stainless Steels 293</p> <p>12.1.1 Microstructure Evolution in Stainless Steels 293</p> <p>12.1.2 Mechanisms of Ferrite Formation 294</p> <p>12.1.3 Prediction of Ferrite Content 296</p> <p>12.1.4 Effect of Cooling Rate 297</p> <p>12.1.4.1 Changes in Solidification Mode 297</p> <p>12.1.4.2 Dendrite Tip Undercooling 301</p> <p>12.2 Low-Carbon, Low-Alloy Steels 301</p> <p>12.2.1 Microstructure Development 301</p> <p>12.2.2 Factors Affecting Microstructure 302</p> <p>12.2.3 Weld Metal Toughness 306</p> <p>12.3 Ultralow Carbon Bainitic Steels 306</p> <p>12.4 Creep-Resistant Steels 308</p> <p>12.5 Hardfacing of Steels 311</p> <p>References 319</p> <p>Further Reading 321</p> <p>Problems 321</p> <p><b>13 Solidification Cracking </b><b>323</b></p> <p>13.1 Characteristics of Solidification Cracking 323</p> <p>13.2 Theories of Solidification Cracking 323</p> <p>13.2.1 Criterion for Cracking Proposed by Kou 327</p> <p>13.2.2 Index for Crack Susceptibility Proposed by Kou 328</p> <p>13.2.3 Previous Theories 330</p> <p>13.3 Binary Alloys and Analytical Equations 331</p> <p>13.4 Solidification Cracking Tests 334</p> <p>13.4.1 Varestraint Test 334</p> <p>13.4.2 Controlled Tensile Weldability Test 336</p> <p>13.4.3 Transverse-Motion Weldability Test 337</p> <p>13.4.4 Circular-Patch Test 341</p> <p>13.4.5 Houldcroft Test 342</p> <p>13.4.6 Cast-Pin Test 343</p> <p>13.4.7 Ring-Casting Test 344</p> <p>13.4.8 Other Tests 344</p> <p>13.5 Solidification Cracking of Stainless Steels 345</p> <p>13.5.1 Primary Solidification Phase 345</p> <p>13.5.2 Mechanism of Crack Resistance 346</p> <p>13.6 Factors Affecting Solidification Cracking 350</p> <p>13.6.1 Primary Solidification Phase 350</p> <p>13.6.2 Grain Size 350</p> <p>13.6.3 Solidification Temperature Range 351</p> <p>13.6.4 Back Diffusion 354</p> <p>13.6.5 Dihedral Angle 355</p> <p>13.6.6 Grain-Boundary Angle 359</p> <p>13.6.7 Degree of Restraint 360</p> <p>13.7 Reducing Solidification Cracking 360</p> <p>13.7.1 Control of Weld Metal Composition 360</p> <p>13.7.2 Control of Weld Microstructure 363</p> <p>13.7.3 Control of Welding Conditions 365</p> <p>13.7.4 Control of Weld Shape 366</p> <p>Examples 367</p> <p>References 370</p> <p>Further Reading 376</p> <p>Problems 376</p> <p><b>14 Ductility-Dip Cracking </b><b>379</b></p> <p>14.1 Characteristics of Ductility-Dip Cracking 379</p> <p>14.2 Theories of Ductility-Dip Cracking 381</p> <p>14.3 Test Methods 382</p> <p>14.4 Ductility-Dip Cracking of Ni-Base Alloys 384</p> <p>14.4.1 Grain-Boundary Sliding 384</p> <p>14.4.2 Grain-Boundary Misorientation 386</p> <p>14.4.3 Grain-Boundary Tortuosity and Precipitates 386</p> <p>14.4.4 Grain Size 388</p> <p>14.4.5 Factors Affecting Ductility-Dip Cracking 390</p> <p>14.5 Ductility-Dip Cracking of Stainless Steels 390</p> <p>Examples 392</p> <p>References 394</p> <p>Further Reading 396</p> <p>Problems 396</p> <p><b>Part III The Partially Melted Zone </b><b>399</b></p> <p><b>15 Liquation in the Partially Melted Zone </b><b>401</b></p> <p>15.1 Formation of the Partially Melted Zone 401</p> <p>15.2 Liquation Mechanisms 403</p> <p>15.2.1 Mechanism I: Alloy with <i>C</i>o > <i>C</i>SM 404</p> <p>15.2.2 Mechanism II: Alloy with <i>C</i>o < <i>C</i>SM and no A<i>x</i>B<i>y </i>or Eutectic 405</p> <p>15.2.3 Mechanism III: Alloy with <i>C</i>o < <i>C</i>SM and A<i>x</i>B<i>y </i>or Eutectic 405</p> <p>15.2.4 Additional Mechanisms of Liquation 409</p> <p>15.3 Directional Solidification of Liquated Material 411</p> <p>15.4 Grain-Boundary Segregation 411</p> <p>15.5 Loss of Strength and Ductility 413</p> <p>15.6 Hydrogen Cracking 414</p> <p>15.7 Effect of Heat Input 414</p> <p>15.8 Effect of Arc Oscillation 415</p> <p>Examples 416</p> <p>References 417</p> <p>Problems 418</p> <p><b>16 Liquation Cracking </b><b>419</b></p> <p>16.1 Liquation Cracking in Arc Welding 419</p> <p>16.1.1 Crack Susceptibility Tests 421</p> <p>16.1.1.1 Varestraint Testing 421</p> <p>16.1.1.2 Circular-Patch Testing 422</p> <p>16.1.1.3 Hot Ductility Testing 423</p> <p>16.1.2 Mechanism of Liquation Cracking 423</p> <p>16.1.3 Predicting Effect of Filler Metal on Crack Susceptibility 424</p> <p>16.1.4 Factors Affecting Liquation Cracking 430</p> <p>16.1.4.1 Filler Metal 430</p> <p>16.1.4.2 Heat Source 430</p> <p>16.1.4.3 Degree of Restraint 431</p> <p>16.1.4.4 Base Metal 431</p> <p>16.2 Liquation Cracking in Resistance Spot Welding 434</p> <p>16.3 Liquation Cracking in Friction Stir Welding 434</p> <p>16.4 Liquation Cracking in Dissimilar-Metal FSW 439</p> <p>Examples 445</p> <p>References 446</p> <p>Problems 449</p> <p><b>Part IV The Heat-Affected Zone 451</b></p> <p><b>17 Introduction to Solid-State Transformations </b><b>453</b></p> <p>17.1 Work-Hardened Materials 453</p> <p>17.2 Heat-Treatable Al Alloys 455</p> <p>17.3 Heat-Treatable Ni-Base Alloys 458</p> <p>17.4 Steels 461</p> <p>17.4.1 Fe-C Phase Diagram and CCT Diagrams 461</p> <p>17.4.2 Carbon Steels 463</p> <p>17.4.3 Dual-Phase Steels 470</p> <p>17.5 Stainless Steels 471</p> <p>17.5.1 Types of Stainless Steels 471</p> <p>17.5.2 Sensitization of Unstabilized Grades 473</p> <p>17.5.3 Sensitization of Stabilized Grades 473</p> <p>17.5.4 σ-Phase Embrittlement 475</p> <p>Examples 475</p> <p>References 475</p> <p>Problems 477</p> <p><b>18 Heat-Affected-Zone Degradation of Mechanical Properties </b><b>479</b></p> <p>18.1 Grain Coarsening 479</p> <p>18.2 Recrystallization and Grain Growth 480</p> <p>18.3 Overaging in Al Alloys 483</p> <p>18.3.1 Al-Cu-Mg (2000-Series) Alloys 483</p> <p>18.3.1.1 Microstructure and Strength 483</p> <p>18.3.1.2 Effect of Welding Parameters or Process 488</p> <p>18.3.2 Al-Mg-Si (6000-Series) Alloys 489</p> <p>18.3.2.1 Microstructure and Strength 489</p> <p>18.3.2.2 Effect of Welding Processes and Parameters 491</p> <p>18.3.3 Al-Zn-Mg (7000-Series) Alloys 492</p> <p>18.4 Dissolution of Precipitates in Ni-Base Alloys 494</p> <p>18.5 Martensite Tempering in Dual-Phase Steels 498</p> <p>Examples 500</p> <p>References 500</p> <p>Further Reading 502</p> <p>Problems 502</p> <p><b>19 Heat-Affected-Zone Cracking </b><b>505</b></p> <p>19.1 Hydrogen Cracking in Steels 505</p> <p>19.1.1 Cause 505</p> <p>19.1.2 Appearance 506</p> <p>19.1.3 Susceptibility Tests 507</p> <p>19.1.4 Remedies 508</p> <p>19.1.4.1 Preheating 508</p> <p>19.1.4.2 Postweld Heating 509</p> <p>19.1.4.3 Bead Tempering 509</p> <p>19.1.4.4 Use of Low-H Processes and Consumables 509</p> <p>19.1.4.5 Use of Lower-Strength Filler Metals 509</p> <p>19.1.4.6 Use of Austenitic-Stainless-Steel Filler Metals 510</p> <p>19.2 Stress-Relief Cracking in Steels 510</p> <p>19.3 Lamellar Tearing in Steels 514</p> <p>19.4 Type-IV Cracking in Grade 91 Steel 517</p> <p>19.5 Strain-Age Cracking in Ni-Base Alloys 519</p> <p>Examples 524</p> <p>References 524</p> <p>Further Reading 527</p> <p>Problems 528</p> <p><b>20 Heat-Affected-Zone Corrosion </b><b>529</b></p> <p>20.1 Weld Decay of Stainless Steels 529</p> <p>20.2 Weld Decay of Ni-Base Alloys 533</p> <p>20.3 Knife-Line Attack of Stainless Steels 534</p> <p>20.4 Sensitization of Ferritic Stainless-Steel Welds 536</p> <p>20.5 Stress Corrosion Cracking of Austenitic Stainless Steels 537</p> <p>20.6 Corrosion Fatigue of Al Welds 538</p> <p>Examples 538</p> <p>References 539</p> <p>Further Reading 540</p> <p>Problems 540</p> <p><b>Part V Special Topics 541</b></p> <p><b>21 Additive Manufacturing </b><b>543</b></p> <p>21.1 Heat and Fluid Flow 543</p> <p>21.2 Residual Stress and Distortion 545</p> <p>21.3 Lack of Fusion and Gas Porosity 547</p> <p>21.4 Grain Structure 550</p> <p>21.5 Solidification Cracking 550</p> <p>21.6 Liquation Cracking 553</p> <p>21.7 Graded Transition Joints 558</p> <p>21.8 Further Discussions 560</p> <p>Examples 560</p> <p>References 561</p> <p>Further Reading 563</p> <p>Problems 564</p> <p><b>22 Dissimilar-Metal Joining </b><b>565</b></p> <p>22.1 Introduction 565</p> <p>22.2 Arc and Laser Joining 565</p> <p>22.2.1 Al-to-Steel Arc Brazing 566</p> <p>22.2.1.1 Effect of Lap Joint Gap 569</p> <p>22.2.1.2 Effect of Heat Input 575</p> <p>22.2.1.3 Effect of Ultrasonic Vibration 577</p> <p>22.2.1.4 Effect of Preheating 578</p> <p>22.2.1.5 Effect of Postweld Heat Treatment 578</p> <p>22.2.1.6 Butt Joint 579</p> <p>22.2.2 Al-to-Steel Laser Brazing 579</p> <p>22.2.3 Al-to-Steel Laser Welding 580</p> <p>22.2.4 Mg-to-Steel Brazing 582</p> <p>22.2.5 Al-to-Mg Welding 583</p> <p>22.3 Resistance Spot Welding 583</p> <p>22.3.1 Al-to-Steel RSW 583</p> <p>22.3.2 Mg-to-Steel RSW 586</p> <p>22.3.3 Al-to-Mg RSW 588</p> <p>22.4 Friction Stir Welding 589</p> <p>22.4.1 Al-to-Cu FSSW 589</p> <p>22.4.2 FSSW of Al to Galvanized Steel 592</p> <p>22.4.3 Effect of Coating on Al-to-Steel FSSW 597</p> <p>22.5 Other Solid-State Welding Processes 603</p> <p>22.5.1 Friction Welding 603</p> <p>22.5.2 Explosion Welding 606</p> <p>22.5.3 Magnetic Pulse Welding 607</p> <p>Examples 608</p> <p>References 609</p> <p>Further Reading 612</p> <p>Problems 612</p> <p><b>23 Welding of Magnesium Alloys </b><b>613</b></p> <p>23.1 Spatter 613</p> <p>23.1.1 Spatter in Mg GMAW 613</p> <p>23.1.2 Mechanism of Spatter 614</p> <p>23.1.3 Elimination of Spatter 614</p> <p>23.1.4 Irregular Weld Shape and Its Elimination 617</p> <p>23.2 Porosity 618</p> <p>23.2.1 Porosity in Mg GMAW 618</p> <p>23.2.2 Mechanisms of Porosity Formation and Elimination 620</p> <p>23.2.3 Comparing Porosity in Al and Mg Welds 621</p> <p>23.3 Internal Oxide Films 622</p> <p>23.3.1 Mechanism 622</p> <p>23.3.2 Remedies 624</p> <p>23.4 High Crowns 625</p> <p>23.4.1 Mechanism of High-Crown Formation 625</p> <p>23.4.2 Reducing Crown Height 627</p> <p>23.5 Grain Refining 628</p> <p>23.5.1 Ultrasonic Weld Pool Stirring 628</p> <p>23.5.2 Arc Pulsation 629</p> <p>23.5.3 Arc Oscillation 629</p> <p>23.6 Solidification Cracking 629</p> <p>23.7 Liquation Cracking 629</p> <p>23.7.1 A Simple Test for Crack Susceptibility 631</p> <p>23.7.2 Effect of Filler Metals 634</p> <p>23.7.3 Effect of Grain Size 636</p> <p>23.8 Heat-Affected Zone Weakening 636</p> <p>Examples 638</p> <p>References 640</p> <p>Further Reading 641</p> <p>Problems 641</p> <p><b>24 Welding of High-Entropy Alloys and Metal-Matrix Nanocomposites </b><b>643</b></p> <p>24.1 High-Entropy Alloys 643</p> <p>24.1.1 Solidification Microstructure 643</p> <p>24.1.2 Weldability 644</p> <p>24.2 Metal-Matrix Nanocomposites 646</p> <p>24.2.1 Nanoparticles Increasing Weld Size 646</p> <p>24.2.2 Nanoparticles Refining Microstructure 648</p> <p>24.2.3 Nanoparticles Reducing Cracking During Solidification 650</p> <p>24.2.4 Nanoparticles Allowing Friction Stir Welding 651</p> <p>Examples 653</p> <p>References 654</p> <p>Further Reading 655</p> <p>Problems 655</p> <p>Appendix A: Analytical Equations for Susceptibility to Solidification Cracking 657</p> <p>Index 659</p>

<p><b>Sindo Kou,</b> PhD, is Professor and former Chair of the Department of Materials Science and Engineering at the University of Wisconsin. He graduated from MIT with a doctorate in metallurgy. He is a Fellow of American Welding Society and ASM International. <p>He received the William Irrgang Memorial Award (2018), the Honorary Membership Award (2016), and the Comfort A. Adams Lecture Award (2012) from the American Welding Society (AWS); the Yoshiaki Arata Award (2017) from the International Institute of Welding (IIW); the Bruce Chalmers Award (2013) from The Minerals, Metals & Materials Society (TMS); the John Chipman Award (1980) from the Iron and Steel Society of AIME; and Chancellor's Award for Distinguished Teaching (1999) from the University of Wisconsin-Madison. His technical papers won the Warren F. Savage Memorial Award (4 times), Charles H. Jennings Memorial Award (4 times), William Spraragen Award (3 times), A.F. Davis Silver Medal Award, and James F. Lincoln Gold Medal of AWS; and the Magnesium Technology Best Paper Award of TMS.

<p><b>Discover the extraordinary progress that welding metallurgy has experienced over the last two decades</b> <p><i>Welding Metallurgy, Third Edition</i> is the only complete compendium of recent, and not-so-recent, developments in the science and practice of welding metallurgy. Written by Dr. Sindo Kou, this edition covers solid-state welding as well as fusion welding, which now also includes resistance spot welding. It restructures and expands sections on Fusion Zones and Heat-Affected Zones. The former now includes entirely new chapters on microsegregation, macrosegregation, ductility-dip cracking, and alloys resistant to creep, wear and corrosion, as well as a new section on ternary-alloy solidification. The latter now includes metallurgy of solid-state welding. Partially Melted Zones are expanded to include liquation and cracking in friction stir welding and resistance spot welding. New chapters on topics of high current interest are added, including additive manufacturing, dissimilar-metal joining, magnesium alloys, and high-entropy alloys and metal-matrix nanocomposites. <p>Dr. Kou provides the reader with hundreds of citations to papers and articles that will further enhance the reader's knowledge of this voluminous topic. Undergraduate students, graduate students, researchers and mechanical engineers will all benefit spectacularly from this comprehensive resource. <p>The new edition includes new theories/methods of Kou and coworkers regarding: <ul> <li>Predicting the effect of filler metals on liquation cracking</li> <li>An index and analytical equations for predicting susceptibility to solidification cracking</li> <li>A test for susceptibility to solidification cracking and filler-metal effect</li> <li>Liquid-metal quenching during welding</li> <li>Mechanisms of resistance of stainless steels to solidification cracking and ductility-dip cracking</li> <li>Mechanisms of macrosegregation</li> <li>Mechanisms of spatter of aluminum and magnesium filler metals,</li> <li>Liquation and cracking in dissimilar-metal friction stir welding,</li> <li>Flow-induced deformation and oscillation of weld-pool surface and ripple formation</li> <li>Multicomponent/multiphase diffusion bonding</li> </ul> <p>Dr. Kou's <i>Welding Metallurgy</i> has been used the world over as an indispensable resource for students, researchers, and engineers alike. This new <i>Third Edition</i> is no exception.

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