Metallurgy and Mechanics of Welding

Preface xiii Chapter 1. Traditional Welding Processes 1 Guy MURRY and Dominique KAPLAN 1.1. Introduction 1 1.2. Conditions to create metallic bonding 1 1.2.1. Activation of surfaces 2 1.2.2. Elimination of obstacles to bond creation 3 1.2.3. How can we classify the various welding processes? 4 1.3. Industrial welding processes 5 1.3.1. Processes using local fusion of components without mechanical action 5 1.3.2. Processes using local fusion of components with mechanical action 22 1.3.3. Processes using heating without fusion but with mechanical action 27 1.3.4. Processes using mechanical action without heating 29 1.4. Bibliography 30 Chapter 2. High Density Energy Beam Welding Processes: Electron Beam and Laser Beam 31 Abdelkrim CHEHAIBOU and Jean-Claude GOUSSAIN 2.1. Welding properties using high density energy beams 31 2.2. Laser beam welding 33 2.2.1. History 33 2.2.2. Principle 34 2.2.3. Various laser types 35 2.2.4. Laser systems 41 2.2.5. Implementation of laser beam welding 48 2.3. Electron beam welding 52 2.3.1. History 52 2.3.2. Principle 53 2.3.3. Equipment 54 2.3.4. Design and preparation of the parts 60 2.4. Metallurgy of high density energy beam welding 61 2.4.1. Steels 61 2.4.2. Aluminum alloys 67 2.4.3. Nickel-based alloys 70 2.4.4. Titanium-based alloys 72 2.4.5. Zirconium-based alloys 73 2.4.6. Copper-based alloys 73 2.5. Mechanical properties of welded joints 75 2.6. The quality of the assemblies 76 2.6.1. Weld defects 76 2.6.2. Weld inspection methods 78 2.6.3. Standardization and qualification of the welding operating mode 79 2.7. Economic aspects 79 2.7.1. Cost of an electron beam machine 79 2.7.2. Cost of a laser beam machine 80 2.8. Safety 82 2.9. Examples of industrial applications 83 2.9.1. Electron beam welding 83 2.9.2. Laser beam welding 84 2.10. Development prospects 84 2.11. Bibliography 86 Chapter 3. Thermal, Metallurgical and Mechanical Phenomena in the Heat Affected Zone 89 Dominique KAPLAN and Guy MURRY 3.1. Thermal aspects related to welding 89 3.1.1. Maximum temperature attained in the HAZ 95 3.1.2. Cooling parameter in the HAZ 97 3.2. Microstructural modifications in the HAZ: metallurgical consequences of the thermal cycles of welding 102 3.2.1. Transformations in the HAZ during heating 102 3.2.2. Transformations in the HAZ during cooling 107 3.2.3. Case of multipass welding 110 3.2.4. Cold cracking 112 3.2.5. Lamellar tearing 117 3.3. Influence of the thermal cycles on the mechanical properties of the HAZ 118 3.3.1. Modifications of the mechanical properties of hardness or traction in the HAZ 119 3.3.2. Toughness properties of the HAZ 120 3.3.3. Residual stresses associated with welding 123 3.3.4. Influence of residual stress relieving heat treatments in the HAZ 125 3.4. Bibliography 126 Chapter 4. Molten Metal 133 Christian BONNET 4.1. Metallurgical reminders 133 4.2. Molten metal 135 4.2.1. Thermal aspect 135 4.2.2. Chemical aspect 136 4.2.3. Microstructures in ferritic steel welds: relationship with impact strength characteristics 139 4.3. Principal welding defects 149 4.3.1. Hot cracking 149 4.3.2. Cold cracking 157 4.3.3. Reheat cracking 160 4.3.4. Porosities 162 4.4. Bibliography 166 Chapter 5. Welding Products 169 Christian BONNET 5.1. Coated electrodes 169 5.1.1. Constitution of coatings: consequences 169 5.1.2. Basic electrodes and diffusible hydrogen 172 5.2. Fluxes for submerged arc welding 175 5.2.1. Fused fluxes and granular fluxes: advantages and disadvantages 175 5.2.2. Roles of flux: metallurgical aspects 177 5.3. Welding gases 181 5.3.1. Welding processes under a gas flux with an infusible electrode 181 5.3.2. Welding processes under a gas flux with a fusible electrode 184 5.4. Cored wires 191 5.4.1. Manufacturing processes 191 5.4.2. Types of cored wires 192 5.4.3. The titanium/boron effect in relation to rutile cored wires 194 5.5. Choice of welding products 195 5.6. Welding products and the welder\'s environment 197 5.6.1. Coated electrodes 197 5.6.2. Gas mixtures for TIG welding 199 5.6.3. Gas mixtures for GMAW 201 5.6.4. Cored wires 204 5.7. Bibliography 205 Chapter 6. Fatigue Strength of Welded Joints 207 Henri-Paul LIEURADE 6.1. Fatigue strength 207 6.1.1. Introduction 207 6.1.2. Fatigue failure of the principal welded joints 208 6.1.3. Concept of nominal stress 212 6.1.4. Factors in welded joint endurance 213 6.2. Dimensioning of joints in mechanized welding 227 6.2.1. Position of the problem 228 6.2.2. General method (current regulations) 230 6.2.3. Verification methods 231 6.2.4. Geometric structural stress method 232 6.3. Bibliography 237 Chapter 7. Fracture Toughness of Welded Joints 239 Marc BOUSSEAU 7.1. Ductile fracture and brittle fracture 239 7.2. Evaluation of fracture risks in metallic materials 241 7.2.1. Determination of the ductile-brittle transition temperature 241 7.2.2. Determination of a fracture criterion in the elastic linear field 245 7.2.3. Fracture criteria in the elasto-plastic field 249 7.3. Evaluation of fracture risks in welded joints 253 7.3.1. Heterogenities of the weld bead 253 7.3.2. Conditions of specimen taking 255 7.3.3. Determination of the ductile-brittle transition temperature 256 7.3.4. Various methods of toughness evaluation 258 7.4. Consequences of heterogenities on the evaluation of fracture risks 262 7.4.1. Mismatching effects 263 7.4.2. Influence of the base material 266 7.4.3. Influence of filler metals 269 7.4.4. Importance of welding conditions 269 7.4.5. Evaluation and taking account of residual stresses 270 7.5. Bibliography 273 Chapter 8. Welding of Steel Sheets, With and Without Surface Treatments 279 Gilles RIGAUT, Olivier DIERAERT, Pascal VERRIER and Joel CLAEYS 8.1. Spot welding 280 8.1.1. Principle 280 8.1.2. Tests of spot weldability 281 8.1.3. Spot weldability of thin steel sheets 284 8.2. Seam welding 292 8.2.1. Mash seam welding 292 8.2.2. Overlapping seam welding 293 8.2.3. Example applications studied or handled with customers 294 8.3. Laser welding of thin sheets 295 8.3.1. Principle of keyhole laser welding 296 8.3.2. Butt welding 298 8.3.3. Lapped welding 304 8.4. Arc welding 306 8.4.1. TIG welding 306 8.4.2. MAG welding 307 8.5. Bibliography 311 Chapter 9. Welding of Steel Mechanical Components 313 Yves DESALOS and Gerard PRADERE 9.1. Introduction 313 9.2. Specificities of welded bonds in mechanical components 315 9.2.1. Standard welding processes and general recommendations 315 9.2.2. Metallurgical defects in the molten zone and the HAZ 317 9.2.3. Weldability limits for welding with and without remelting 320 9.3. Principal types of welding for mechanical components 323 9.3.1. Electric arc welding and alternatives 324 9.3.2. Welds with reduced HAZ using high density energy sources: laser beam, EB, plasma 327 9.3.3. Friction welding 333 9.3.4. Butt welding by the Joule effect 337 9.3.5. Diffusion welding in the solid phase 341 9.4. Specifications and quality control of the weldings for these components 344 9.4.1. Weld quality specifications 345 9.4.2. The quality assurance plan of the weld 349 9.5. Developments and trends 353 9.5.1. Evolution of the context 353 9.5.2. Favored processes 353 9.6. Conclusions 355 9.7. Bibliography 356 Chapter 10. Welding Steel Structures 359 Jean-Pierre PESCATORE and Jean-Henri BORGEOT 10.1. Introduction 359 10.1.1. History 359 10.1.2. Applications 361 10.2. Steels for steel structures 362 10.2.1. Grades and qualities 362 10.2.2. Steels used 363 10.3. Steel construction welding processes and techniques 364 10.3.1. Table of the usual processes 364 10.3.2. Preliminary operation: tack weld 365 10.3.3. Particular welding techniques 365 10.3.4. Usual welding positions 367 10.3.5. Edge preparation 367 10.4. Welding distortion 369 10.4.1. Precautions in execution 369 10.4.2. Straightening 371 10.5. Defects and their prevention 371 10.5.1. Cracks 371 10.5.2. Fracture 372 10.5.3. Other thermal and mechanical precautions 373 10.6. Specificities of non-destructive testing of steel structures 374 10.7. Developmental perspectives 374 Chapter 11. Welding Heavy Components in the Nuclear Industry 375 Francois FAURE and Leon DUNAND-ROUX 11.1. General presentation of a PWR pressure vessel 375 11.2. Main materials used for manufacturing 376 11.2.1. Principle of material choice - construction code 376 11.2.2. Low alloyed steels for pressure vessels 377 11.2.3. Austenitic stainless steel circuits 379 11.2.4. Nickel alloy parts 380 11.3. Welding of large low alloy steel components 381 11.3.1. Properties aimed for 382 11.3.2. Procedural description 382 11.3.3. Welding with coated electrodes 387 11.4. Cladding 387 11.4.1. Cladding method 389 11.4.2. Cladding inspection 389 11.5. Welding of stainless steel circuits 390 11.6. Dissimilar metal interfaces 393 11.7. Welding of steam generator pipes 394 11.8. Conclusions 396 Chapter 12. Welding Stainless Steels 397 Jean-Louis MOIRON 12.1. Definitions 397 12.2. Principal stainless steel families 397 12.3. Metallurgical structures 399 12.4. Constitution diagrams 402 12.4.1. Introduction 402 12.4.2. Calculation of the equivalent formulae 402 12.4.3. Constitution diagrams 403 12.5. Welding ferritic stainless steels 408 12.5.1. Introduction 408 12.5.2. Risks incurred in welding 409 12.5.3. Stabilization 410 12.5.4. Risks of embrittlement 411 12.5.5. Filler products 412 12.5.6. Shielding gases 413 12.5.7. Summary: partial conclusion 413 12.6. Welding of martensitic stainless steels 414 12.6.1. Introduction 414 12.6.2. List of martensitic stainless steels 415 12.6.3. Effect of the elements C, Cr and Ni on the y loop 415 12.6.4. Metallurgical weldability of martensitic stainless steels 416 12.6.5. Conclusion: partial summary 417 12.7. Welding of austenitic stainless steels 418 12.7.1. Introduction 418 12.7.2. Risks incurred during welding 418 12.7.3. Carbide precipitation 419 12.7.4. Hot cracking 420 12.7.5. The sigma phase 421 12.7.6. Filler products 422 12.7.7. Shielding gas 422 12.8. The welding of austeno-ferritic stainless steels (duplex) 423 12.8.1. Introduction 423 12.8.2. Risks incurred in welding 423 12.8.3. Principal austeno-ferritic stainless steels 424 12.8.4. Weldability of austeno-ferritic steels 425 12.8.5. Filler products 426 12.8.6. Shielding gases 426 12.9. Heterogenous welding 427 12.9.1. Reminder of definitions 427 12.9.2. Treatment and forecast of heterogenous welds 427 12.10. Finishing of welds 429 12.11. Glossary 430 12.12. Bibliography 431  Chapter 13.Welding Aluminum Alloys 433 Michel COURBIERE 13.1. Metallurgy of welding 433 13.1.1. Weldability of aluminum alloys (steels/aluminum comparison) 433 13.1.2. Filler metals 436 13.2. Welding techniques 440 13.2.1. Introduction 440 13.2.2. Arc welding processes (TIG-MIG) 441 13.2.3. Electric resistance welding 447 13.2.4. Flash welding 448 13.2.5. Friction welding and friction stir welding 449 13.2.6. Electron beam welding 451 13.2.7. Laser welding 452 13.2.8. Other techniques 453 13.3. Preparation and use of semi-finished aluminum welding products 454 13.3.1. Particularities of aluminum alloy surfaces 454 13.3.2. Storage 455 13.3.3. Surface preparation 455 13.3.4. Cleaning of the weld beads 456 13.4. Deformations 457 13.4.1. Introduction 457 13.4.2. Steel/aluminum comparison (deformation due to heating) 458 13.4.3. Shrinkage 461 13.4.4. Basic rules 461 13.5. Dimensioning of the welded structures 464 13.5.1. Static 464 13.5.2. Fatigue dimensioning 467 13.5.3. Rules governing the optimal use of welded structures 467 13.6. Welding defects 468 13.7. Health and safety 471 13.8. Bibliography 471 Chapter 14. Standardization: Organization and Quality Control in Welding 473 Jean-Paul GOURMELON 14.1. Introduction 473 14.2. Standards of general organization of quality 474 14.2.1. Presentation 474 14.2.2. Principles 475 14.2.3. Analysis 475 14.3. Standards for welding procedure qualification 479 14.4. Non-destructive testing standards 484 14.5. Conclusion 487 List of Authors 489 Index 491