Metallurgy and Mechanics of Welding

Regis Blondeau is an Engineer of the National School of Electrochemistry and Electrometallurgy of Grenoble, France.

• Preface xiiiChapter 1. Traditional Welding Processes 1Guy MURRY and Dominique KAPLAN1.1. Introduction 11.2. Conditions to create metallic bonding 11.2.1. Activation of surfaces 21.2.2. Elimination of obstacles to bond creation 31.2.3. How can we classify the various welding processes? 41.3. Industrial welding processes 51.3.1. Processes using local fusion of components without mechanical action 51.3.2. Processes using local fusion of components with mechanical action 221.3.3. Processes using heating without fusion but with mechanical action 271.3.4. Processes using mechanical action without heating 291.4. Bibliography 30Chapter 2. High Density Energy Beam Welding Processes: Electron Beam and Laser Beam 31Abdelkrim CHEHAÏBOU and Jean-Claude GOUSSAIN2.1. Welding properties using high density energy beams 312.2. Laser beam welding 332.2.1. History 332.2.2. Principle 342.2.3. Various laser types 352.2.4. Laser systems 412.2.5. Implementation of laser beam welding 482.3. Electron beam welding 522.3.1. History 522.3.2. Principle 532.3.3. Equipment 542.3.4. Design and preparation of the parts 602.4. Metallurgy of high density energy beam welding 612.4.1. Steels 612.4.2. Aluminum alloys 672.4.3. Nickel-based alloys 702.4.4. Titanium-based alloys 722.4.5. Zirconium-based alloys 732.4.6. Copper-based alloys 732.5. Mechanical properties of welded joints 752.6. The quality of the assemblies 762.6.1. Weld defects 762.6.2. Weld inspection methods 782.6.3. Standardization and qualification of the welding operating mode 792.7. Economic aspects 792.7.1. Cost of an electron beam machine 792.7.2. Cost of a laser beam machine 802.8. Safety 822.9. Examples of industrial applications 832.9.1. Electron beam welding 832.9.2. Laser beam welding 842.10. Development prospects 842.11. Bibliography 86Chapter 3. Thermal, Metallurgical and Mechanical Phenomena in the Heat Affected Zone 89Dominique KAPLAN and Guy MURRY3.1. Thermal aspects related to welding 893.1.1. Maximum temperature attained in the HAZ 953.1.2. Cooling parameter in the HAZ 973.2. Microstructural modifications in the HAZ: metallurgical consequences of the thermal cycles of welding 1023.2.1. Transformations in the HAZ during heating 1023.2.2. Transformations in the HAZ during cooling 1073.2.3. Case of multipass welding 1103.2.4. Cold cracking 1123.2.5. Lamellar tearing 1173.3. Influence of the thermal cycles on the mechanical properties of the HAZ 1183.3.1. Modifications of the mechanical properties of hardness or traction in the HAZ 1193.3.2. Toughness properties of the HAZ 1203.3.3. Residual stresses associated with welding 1233.3.4. Influence of residual stress relieving heat treatments in the HAZ 1253.4. Bibliography 126Chapter 4. Molten Metal 133Christian BONNET4.1. Metallurgical reminders 1334.2. Molten metal 1354.2.1. Thermal aspect 1354.2.2. Chemical aspect 1364.2.3. Microstructures in ferritic steel welds: relationship with impact strength characteristics 1394.3. Principal welding defects 1494.3.1. Hot cracking 1494.3.2. Cold cracking 1574.3.3. Reheat cracking 1604.3.4. Porosities 1624.4. Bibliography 166Chapter 5. Welding Products 169Christian BONNET5.1. Coated electrodes 1695.1.1. Constitution of coatings: consequences 1695.1.2. Basic electrodes and diffusible hydrogen 1725.2. Fluxes for submerged arc welding 1755.2.1. Fused fluxes and granular fluxes: advantages and disadvantages 1755.2.2. Roles of flux: metallurgical aspects 1775.3. Welding gases 1815.3.1. Welding processes under a gas flux with an infusible electrode 1815.3.2. Welding processes under a gas flux with a fusible electrode 1845.4. Cored wires 1915.4.1. Manufacturing processes 1915.4.2. Types of cored wires 1925.4.3. The titanium/boron effect in relation to rutile cored wires 1945.5. Choice of welding products 1955.6. Welding products and the welder’s environment 1975.6.1. Coated electrodes 1975.6.2. Gas mixtures for TIG welding 1995.6.3. Gas mixtures for GMAW 2015.6.4. Cored wires 2045.7. Bibliography 205Chapter 6. Fatigue Strength of Welded Joints 207Henri-Paul LIEURADE6.1. Fatigue strength 2076.1.1. Introduction 2076.1.2. Fatigue failure of the principal welded joints 2086.1.3. Concept of nominal stress 2126.1.4. Factors in welded joint endurance 2136.2. Dimensioning of joints in mechanized welding 2276.2.1. Position of the problem 2286.2.2. General method (current regulations) 2306.2.3. Verification methods 2316.2.4. Geometric structural stress method 2326.3. Bibliography 237Chapter 7. Fracture Toughness of Welded Joints 239Marc BOUSSEAU7.1. Ductile fracture and brittle fracture 2397.2. Evaluation of fracture risks in metallic materials 2417.2.1. Determination of the ductile-brittle transition temperature 2417.2.2. Determination of a fracture criterion in the elastic linear field 2457.2.3. Fracture criteria in the elasto-plastic field 2497.3. Evaluation of fracture risks in welded joints 2537.3.1. Heterogenities of the weld bead 2537.3.2. Conditions of specimen taking 2557.3.3. Determination of the ductile-brittle transition temperature 2567.3.4. Various methods of toughness evaluation 2587.4. Consequences of heterogenities on the evaluation of fracture risks 2627.4.1. Mismatching effects 2637.4.2. Influence of the base material 2667.4.3. Influence of filler metals 2697.4.4. Importance of welding conditions 2697.4.5. Evaluation and taking account of residual stresses 2707.5. Bibliography 273Chapter 8. Welding of Steel Sheets, With and Without Surface Treatments 279Gilles RIGAUT, Olivier DIERAERT, Pascal VERRIER and Joël CLAEYS8.1. Spot welding 2808.1.1. Principle 2808.1.2. Tests of spot weldability 2818.1.3. Spot weldability of thin steel sheets 2848.2. Seam welding 2928.2.1. Mash seam welding 2928.2.2. Overlapping seam welding 2938.2.3. Example applications studied or handled with customers 2948.3. Laser welding of thin sheets 2958.3.1. Principle of keyhole laser welding 2968.3.2. Butt welding 2988.3.3. Lapped welding 3048.4. Arc welding 3068.4.1. TIG welding 3068.4.2. MAG welding 3078.5. Bibliography 311Chapter 9. Welding of Steel Mechanical Components 313Yves DESALOS and Gérard PRADERE9.1. Introduction 3139.2. Specificities of welded bonds in mechanical components 3159.2.1. Standard welding processes and general recommendations 3159.2.2. Metallurgical defects in the molten zone and the HAZ 3179.2.3. Weldability limits for welding with and without remelting 3209.3. Principal types of welding for mechanical components 3239.3.1. Electric arc welding and alternatives 3249.3.2. Welds with reduced HAZ using high density energy sources: laser beam, EB, plasma 3279.3.3. Friction welding 3339.3.4. Butt welding by the Joule effect 3379.3.5. Diffusion welding in the solid phase 3419.4. Specifications and quality control of the weldings for these components 3449.4.1. Weld quality specifications 3459.4.2. The quality assurance plan of the weld 3499.5. Developments and trends 3539.5.1. Evolution of the context 3539.5.2. Favored processes 3539.6. Conclusions 3559.7. Bibliography 356Chapter 10. Welding Steel Structures 359Jean-Pierre PESCATORE and Jean-Henri BORGEOT10.1. Introduction 35910.1.1. History 35910.1.2. Applications 36110.2. Steels for steel structures 36210.2.1. Grades and qualities 36210.2.2. Steels used 36310.3. Steel construction welding processes and techniques 36410.3.1. Table of the usual processes 36410.3.2. Preliminary operation: tack weld 36510.3.3. Particular welding techniques 36510.3.4. Usual welding positions 36710.3.5. Edge preparation 36710.4. Welding distortion 36910.4.1. Precautions in execution 36910.4.2. Straightening 37110.5. Defects and their prevention 37110.5.1. Cracks 37110.5.2. Fracture 37210.5.3. Other thermal and mechanical precautions 37310.6. Specificities of non-destructive testing of steel structures 37410.7. Developmental perspectives 374Chapter 11. Welding Heavy Components in the Nuclear Industry 375François FAURE and Léon DUNAND-ROUX11.1. General presentation of a PWR pressure vessel 37511.2. Main materials used for manufacturing 37611.2.1. Principle of material choice – construction code 37611.2.2. Low alloyed steels for pressure vessels 37711.2.3. Austenitic stainless steel circuits 37911.2.4. Nickel alloy parts 38011.3. Welding of large low alloy steel components 38111.3.1. Properties aimed for 38211.3.2. Procedural description 38211.3.3. Welding with coated electrodes 38711.4. Cladding 38711.4.1. Cladding method 38911.4.2. Cladding inspection 38911.5. Welding of stainless steel circuits 39011.6. Dissimilar metal interfaces 39311.7. Welding of steam generator pipes 39411.8. Conclusions 396Chapter 12. Welding Stainless Steels 397Jean-Louis MOIRON12.1. Definitions 39712.2. Principal stainless steel families 39712.3. Metallurgical structures 39912.4. Constitution diagrams 40212.4.1. Introduction 40212.4.2. Calculation of the equivalent formulae 40212.4.3. Constitution diagrams 40312.5. Welding ferritic stainless steels 40812.5.1. Introduction 40812.5.2. Risks incurred in welding 40912.5.3. Stabilization 41012.5.4. Risks of embrittlement 41112.5.5. Filler products 41212.5.6. Shielding gases 41312.5.7. Summary: partial conclusion 41312.6. Welding of martensitic stainless steels 41412.6.1. Introduction 41412.6.2. List of martensitic stainless steels 41512.6.3. Effect of the elements C, Cr and Ni on the y loop 41512.6.4. Metallurgical weldability of martensitic stainless steels 41612.6.5. Conclusion: partial summary 41712.7. Welding of austenitic stainless steels 41812.7.1. Introduction 41812.7.2. Risks incurred during welding 41812.7.3. Carbide precipitation 41912.7.4. Hot cracking 42012.7.5. The sigma phase 42112.7.6. Filler products 42212.7.7. Shielding gas 42212.8. The welding of austeno-ferritic stainless steels (duplex) 42312.8.1. Introduction 42312.8.2. Risks incurred in welding 42312.8.3. Principal austeno-ferritic stainless steels 42412.8.4. Weldability of austeno-ferritic steels 42512.8.5. Filler products 42612.8.6. Shielding gases 42612.9. Heterogenous welding 42712.9.1. Reminder of definitions 42712.9.2. Treatment and forecast of heterogenous welds 42712.10. Finishing of welds 42912.11. Glossary 43012.12. Bibliography 431 Chapter 13.Welding Aluminum Alloys 433Michel COURBIÈRE13.1. Metallurgy of welding 43313.1.1. Weldability of aluminum alloys (steels/aluminum comparison) 43313.1.2. Filler metals 43613.2. Welding techniques 44013.2.1. Introduction 44013.2.2. Arc welding processes (TIG-MIG) 44113.2.3. Electric resistance welding 44713.2.4. Flash welding 44813.2.5. Friction welding and friction stir welding 44913.2.6. Electron beam welding 45113.2.7. Laser welding 45213.2.8. Other techniques 45313.3. Preparation and use of semi-finished aluminum welding products 45413.3.1. Particularities of aluminum alloy surfaces 45413.3.2. Storage 45513.3.3. Surface preparation 45513.3.4. Cleaning of the weld beads 45613.4. Deformations 45713.4.1. Introduction 45713.4.2. Steel/aluminum comparison (deformation due to heating) 45813.4.3. Shrinkage 46113.4.4. Basic rules 46113.5. Dimensioning of the welded structures 46413.5.1. Static 46413.5.2. Fatigue dimensioning 46713.5.3. Rules governing the optimal use of welded structures 46713.6. Welding defects 46813.7. Health and safety 47113.8. Bibliography 471Chapter 14. Standardization: Organization and Quality Control in Welding 473Jean-Paul GOURMELON14.1. Introduction 47314.2. Standards of general organization of quality 47414.2.1. Presentation 47414.2.2. Principles 47514.2.3. Analysis 47514.3. Standards for welding procedure qualification 47914.4. Non-destructive testing standards 48414.5. Conclusion 487List of Authors 489Index 491