Year: 1994 Language: english Author: George E. Linnert Genre: Textbook Publisher: GML Publications Edition: 4th ISBN: 0-8717 1-457-4 Format: PDF Quality: eBook Pages count: 963 Description: Readers of Welding Metallurgy in their comments about previous Volumes 1 and 2 of the Third Edition have offered helpful suggestions toward betterment of future editions. All offerings from students, engineers, experienced welding personnel, and educators have been carefully weighed by the author in planning this present revision. A principal aim in carrying out this work was to acquire updated information wherever available, but input from readers prompted several changes. One change will be found in the sequence of chapters, which now provides more logical progression from the structures and properties of metals, through the mechanics and effects of heating for welding, and finally to metallurgical description of typical welds in steel. Also, the remodeled text now includes additional material of a fundamental nature to assist in developing broader, analytical explanations for the chemical and physical events that arise in welding. The need for this assistance had been voiced by readers who are confronted with the complex technology of welding, but who have not had exposure to chemistry and physics of the depth needed to rationalize the phenomena encountered. Relationships between fundamental features of metals and their behavior in welding are pointed out to encourage development of more complete understanding of each particular happening in welding. This kind of awareness of the factors involved and the mechanics entailed aids greatly when a decision must be made regarding the most effective measure for dealing with a given troublesome situation.
Contents
Chapter One: Background to Welding Metallurgy ............................................ 1 MILESTONES IN WELDING HISTORY ........................................................... 1 THE FUTURE OF WELDING ............................................................................ 4 WHAT IS WELDING METALLURGY? ............................................................. 6 PUTTING WELDING METALLURGY TO USE .............................................. 12 WELDING TECHNOLOGY RESOURCES .................................................... -12 SUGGESTED READING ................................................................................ 15 Chapter Two: The Structure of Metals ..................................................................... 18 ATOMS ............................................................................................................ 18 Elementary Particles ................................................................................... 20 Electrons ................................................................................................. 22 Positrons ................................................................................................. 26 Protons .................................................................................................... 27 Ne ut rons .................................................................................................. 28 Atom Construction ....................................................................................... 32 Isotopes of Elements .............................................................................. 33 Isobars .................................................................................................... 34 Atomic Weight ......................................................................................... 34 Atomic Mass ........................................................................................... 34 Atom Valency .......................................................................................... 35 Ionization ................................................................................................. 36 Radioactivity ............................................................................................ 37 Atom Size or Diameter ............................................................................ 38 THE ELEMENTS ............................................................................................. 39 AGGREGATES OF ATOMS ........................................................................... 41 The Solid State ............................................................................................ 45 The Crystalline Solids ............................................................................. 45 Amorphous Solids ................................................................................... 47 The Liquid State .......................................................................................... 48 The Gaseous State ..................................................................................... 49 FUNDAMENTALS OF CRYSTALS ................................................................ 50 Identification of Planes and Directions in Crystals ...................................... 56 Basic Types of Crystals ............................................................................... 56 Inert Gas Crystals ................................................................................... 58 Covalent Crystals. ................................................................................... 59 Ionic Crystals .......................................................................................... 58 Metallic Crystals ...................................................................................... 59 THE CRYSTALLINE STRUCTURE OF METALS ........................................... 61 How Does a Crystal Grow from the Melt? .................................................. 64 The Formation of Dendrites ....................................................................... -66 The Formation of Grains ............................................................................. 68 The Shape of Grains ............................................................................... 71 The Size of Grains .................................................................................. 72 Undercooling ............................................................................................... 72 THE IMPORTANCE OF A CRYSTALLINE STRUCTURE ............................. 74 Allotropic Transformation ............................................................................ 75 Solubility in the Solid State ......................................................................... 76 Slip in Crystalline Structures ................................................................... 77 Slip and Lattice Orientation ..................................................................... 78 Slip in Polycrystalline Metals .................................................................. 79 Observing Slip ......................................................................................... 80 Twinning in Crystalline Structures .......................................................... 81 Lattice Imperfections: Dislocations .............................................................. 84 Point Defects ........................................................................................... 85 Edge Dislocations ................................................................................... 86 Screw Dislocations .................................................................................. 88 Stacking Faults ....................................................................................... 88 Other Lattice Imperfections ..................................................................... 88 Cold-Working Metals ................................................................................... 88 EXAMINATION OF METAL STRUCTURES .................................................. 91 Fracture Appearance Assessment .............................................................. 92 Metallography .............................................................................................. 92 Metallography Using Optical Microscopy ................................................ 92 Quantitative Metallography .................................... ........................... 105 Metallography Using the Electron Microscope ....... ........................... 106 Metallography Using Ion Microscopy .................................................... 115 Tunnel-Effect Microscopy ..................................................................... 116 ... 116 ........................................... 121 FRACTOGRAPHY ........................................................................................ 123 SUGGESTED READING .............................................................................. 131 Plasticity in Metallic Crystals ....................................................................... 77 Chemical Analysis of Microstructural Constituents ..... Newer Techniques in Metallurgy .... Chapter Three: The Properties of Metals ................................................................ 133 STRUCTURE SENSITIVITY OF PROPERTIES ........................................... 133 DIRECTIONALITY IN PROPERTIES ............................................................ 135 MECHANICAL PROPERTIES ...................................................................... 136 Elastic Behavior of Metals ......................................................................... 137 Young's Modulus of Elasticity ............................................................... 139 Poisson's Ratio ..................................................................................... 139 Limits of Elasticity and Proportionality .................................................. 141 Plastic Yielding in Metals .......................................................................... 142 Yield Strength ....................................................................................... 143 Breaking Strength of Metals ...................................................................... 143 Tensile Strength .................................................................................... 144 True Stress and True Strain ................................................................. 144 Notched Tensile Strength ..................................................................... 147 Ductility ...................................................................................................... 147 Elongation ............................................................................................. 148 Reduction of Area ................................................................................. 149 Ductility Indications from Special Tests ................................................ 149 Hardness ................................................................................................... 149 Microhardness Testing .......................................................................... 151 Dynamic Hardness Testing ................................................................... 152 Scratch Hardness Testing ..................................................................... 153 Conversion of Hardness Numbers ........................................................ 153 Toughness ................................................................................................. 154 Introduction of Impact Testing .............................................................. 155 FRACTURE IN METALS .............................................................................. 156 Ductile Fracture ......................................................................................... 158 Brittle Fracture ........................................................................................... 159 Intergranular Fracture ................................................................................ 162 Conditions Affecting Fracture Toughness ................................................. 164 Effect of Temperature ........................................................................... 164 Effect of Stress Axiality ......................................................................... 166 Stress Gradient ..................................................................................... 169 Stress Multiaxiality ................................................................................ 170 Effect of Rate of Strain .......................................................................... 171 Effect of Cyclic Stress (Fatigue) ................................................................ 174 Fatigue Crack Initiation ......................................................................... 176 Fatigue Crack Propagation ................................................................... 176 Cyclic Stress Limits to Avoid Fatigue Failure ....................................... 181 Cyclic Stress Conditions ....................................................................... 183 Variable Loading and Cumulative Fatigue Damage .............................. 185 FRACTURE MECHANICS: ASSESSMENT OF FRACTURE TOUGHNESS .................................................................................................. 188 Brittle Fracture Test Parameters ................................................................. 190 Section Dimensions ................................................................................ 192 Plotting Coordinates ............................................................................... 192 Crack Surface Displacement Mode ........................................................ 193 Plane-Strain ............................................................................................ 195 Plane-Stress ........................................................................................... 195 Stress Distribution ................................................................................... 196 Use of Linear-Elastic Fracture Mechanics ................................ Crack Tip Opening Displacement Testing ................................ The J-Integral Test Method ...................................................... Procedures for Evaluating Propensity for Brittle Fracture ............ Development of Elastic-Plastic Fracture Mechanics .................................. 201 Fatigue Cracking Assessment by Fracture Mechanics .............................. 215 Mechanical Properties at Low Temperature ............................................... 218 Strength at Low Temperature ................................................................. 219 Test Methods for Toughness Evaluation ................................................ 226 Correlation of Results from Fracture Toughness Tests ......................... 236 Improved Mechanical Properties for Low-Temperature Service ................ 238 Impact Toughness at Low Temperature ................................................ 220 Mechanical Properties at Elevated and High Temperatures. ..................... 238 Short-Time Elevated Temperature Testing ............................................ 241 Long-Time Elevated Temperature Testing ............................................. 242 Mechanical Properties After Plastic Work ................................................... 247 Hot Work ................................................................................................. 248 Cold Work ............................................................................................... 248 Peening ................................................................................................... 248 Irradiation ................................................................................................ 249 PHYSICAL PROPERTIES .............................................................................. 258 Density ........................................................................................................ 258 Thermal Properties ........................................................... ....................... 259 Specific Heat ........................................................................................... 260 Thermal Conductivity .............................................................................. 261 Melting Point or Melting Range .............................................................. 264 Heat of Fusion ........................................................................................ 264 Viscosity and Surface Tension of Molten Metals ................................... 264 Boiling Point and Heat of Vaporization ................................................... 266 Thermal Expansion and Contraction ...................................................... 266 Thermionic Work Function ... ............................................................... 268 Electrical Properties .................................................................................... 268 Magnetic Properties .................................................................................... 270 Evaluation of Magnetization ................................................................... 272 Summary of Magnetic Behavior ............................................................. 273 Involvement of Magnetization in Welding ............................................... 274 CHEMICAL PROPERTIES ............................................................................. 274 Corrosion of Metals ..................................................................................... 275 Corrosion in Aqueous Solutions ............................................................. 276 Corrosion in Hot Gases .......................................................................... 282 Corrosion in Molten Metals ..................................................................... 282 Corrosion in Molten Salt ......................................................................... 283 Forms of Corrosion Pertinent to Weldments .............................................. 283 Stress Corrosion Cracking (SCC) .......................................................... 284 SUGGESTED READING ................................................................................ 293 Chapter Four: Effects of Alloying Elements ....................................................... 295 ALLOYING .................................................................................................... 295 Alloys in the Liquid State ........................................................................... 296 Phase Diagrams ........................................................................................ 299 Binary Phase Diagrams ........................................................................ 304 Ternary Phase Diagrams ...................................................................... 307 Phase Diagrams for Multi-Element Alloys ............................................ 308 Alloys in the Solid State ............................................................................ 310 Factors Influencing Solid Solubility ....................................................... 310 Formation of Intermediate Phases and Compounds ............................. 316 Mechanisms and General Effects of Alloying ........................................... 316 Role of Crystalline Structure ................................................................. 317 Role of Microstructure ........................................................................... 319 Mechanisms for Altering Mechanical Properties ................................... 319 ALLOYING ELEMENTS IN IRON ................................................................. 326 Carbon ......................................................................................................... 329 Analysis of the Iron-Iron Carbide Diagram ............................................. 331 Manganese .................................................................................................. 337 Phosphorus ................................................................................................. 338 Sulfur and Selenium .................................................................................... 340 Si I icon .......................................................................................................... 342 Copper ......................................................................................................... 343 Chromium .................................................................................................... 345 Nickel ........................................................................................................... 346 Molybdenum ................................................................................................ 346 Niobium (Columbium) ................................................................................. 347 Vanadium .................................................................................................... 348 Alum i num .................................................................................................... 348 Nitrogen ....................................................................................................... 349 Titanium ....................................................................................................... 352 Boron ........................................................................................................... 354 Cobalt .......................................................................................................... 355 Tungsten ..................................................................................................... 355 Lead ............................................................................................................ 355 Other Alloying Elements ............................................................................. 356 BENEFIT OF REVERSING THE ALLOYING TREND ................................... 357 Residual Elements ...................................................................................... 358 SUGGESTED READING .............................................................................. 359 Chapter Five: Types of Steel and Their Manufacture ................................. 361 GENERAL CATEGORIES OF IRON AND STEEL ....................................... 361 IRON PRODUCTION BY ORE REDUCTION ............................................... 362 Blast Furnace ............................................................................................ 362 Direct Reduction Processes ........................... ....................................... 365 CAST IRON ................................................................................................... 366 WROUGHT IRON .......................................................................................... 367 POWDER METALLURGY ............................................................................ 367 STEELMAKING PROCESSES ..................................................................... 368 Significance of Acid and Basic Steelmaking ............................................. 368 Bessemer Converter ................................................................................ 369 Open Hearth Furnace ............................................................................... 370 Rimmed Steel ....................................................................................... 372 Capped Steel ........................................................................................ 373 Killed Steel ............................................................................................ 373 Semikilled Steel .................................................................................... 379 Vacuum Deoxidized Steel ..................................................................... 379 Oxygen Steelmaking ................................................................................. 380 Sasic Oxygen Steelmaking .................................................. L-D Process ..................................................................... Kaldo Process ....................................................................................... 383 Off-Gas BOF ......................................................................................... 383 Q-BOP Process .................................................................................... 383 Lance-Bubbling-Equilibrium .................................................................. 385 Ladle Refining ........................................................................................... 385 Slag Removal ........................................................................................ 385 Mixing Capability ................................................................................... 386 Alloying Additions ............................. ........................................... 386 Vacuum Treatment .......................... ........................................... 386 Temperature Adjustment ................. ........................................... 387 Desu Ifu rization ...................................................................................... 388 Electric-Arc Furnace .................................................................................. 389 Electric-Induction Furnace ...................... ............................................... 389 Electroslag Remelting ............................................................................... 391 SPECIAL MELTING PROCESSES .............................................................. 392 . . Vacuum Induction Melting ......................................................................... 392 Vacuum Consumable-Electrode Remelting .............................................. 393 Electron-Beam Melting .............................................................................. 395 Argon-Oxygen Decarburization (AOD) ...................................................... 396 FOUNDRY AND STEEL MILL OPERATIONS ............................................. 397 Ingot Steelmaking Practice ....................................................................... 398 Continuous Casting of Steel ...................................................................... 400 HOT WORKING OPERATIONS ................................................................... 404 Thermo-Mechanical Control Process (T-MCP) ......................................... 406 COLD FINISHING ......................................................................................... 407 HEAT TREATMENT ...................................................................................... 408 CONTINUOUS COATING OF STRIP STEEL IN COILS .............................. 409 TYPES OF STEEL ........................................................................................ 410 Carbon Steels ............................................................................................ 41 O Alloy Steels ................................................................................................ 411 Construction .......................................................................................... 412 Low-Temperature Service ..................................................................... 413 Elevated Temperature Service ............................................................. 413 High-Alloy Steels ....................................................................................... 413 Austenitic Manganese Steel ................................................................. 413 Stainless Steels .................................................................................... 414 Heat-Resisting Steels ........................................................................... 415 Tool Steels ................................................................................................ 415 STANDARDS AND SPECIFICATIONS FOR STEELS ................................. 416 Unified Numbering System ....................................................................... 416 AISI-SAE System of Standard Carbon and Alloy Steels ........................... 418 ASTM Standards ....................................................................................... 420 API Specifications ..................................................................................... 424 Aerospace Material Specifications ............................................................ 426 ASME Material Specifications ................................................................... 426 AWS Specifications. Code6 and Rules ..................................................... 429 CARBON AND ALLOY STEEL USED IN WELDED CONSTRUCTION ...... 430 Qualities of Steel Important to Welding ..................................................... 431 Factors Affecting the Weldability of Steel ................................................. 432 Chemical Composition .......................................................................... 432 Mechanical Properties .......................................................................... 434 Metallurgical Structure .......................................................................... 435 Internal Soundness ............................................................................... 435 Cleanliness ............................................................................................ 436 THE FUTURE OF STEELS AND THEIR WELDABILI TY ............................. 437 New Steels and Product Forms ................................................................ 437 Dissimilar-Metal Welding ........................................................................... 437 Repair Welding - The Ultimate Challenge .............................................. 439 SUGGESTED READING .............................................................................. 439 Automotive. Aircraft. and Machinery ..................................................... 412 Chapter Six: Welding Methods and Processes ............................................ 444 SOLID-STATE WELDING (SSW) ................................................................. 444 FUSION WELDING ......................................................................................... 445 BRAZING AND SOLDERING ......................................................................... 445 HEAT SOURCES FOR WELDING AND CUTTING ....................................... 448 Electrical Heat Generation .......................................................................... 448 Electric Arc .............................................................................................. 448 Electron Beam ........................................................................................ 459 Electric Resistance ...................................................................................... 461 Electromagnetic Radiation .......................................................................... 461 Laser Beams ........................................................................................... 463 Chemical Heat Generation .......................................................................... 465 Mechanical Heat Generation ...................................................................... 466 THE WELDING AND CUTTING PROCESSES ............................................. 467 Power Sources for Arc Welding ............................................................. 467 Auxiliary Equipment for Arc Welding ...................................................... 470 Basic Forms of Arc Welding ................................................................... 471 Stud Arc Welding (SW) ........................................................................... 477 Gas Tungsten Arc Welding (GTAW) ...................................................... 478 Gas Metal Arc Welding (GMAW) ............................................................ 489 Arc Welding Process ................................................................................... 467 Shielded Metal Arc Welding (SMAW) ..................................................... 472 Flux Cored Arc Welding (FCAW) ........................................................... 501 Submerged Arc Welding (SAW) ............................................................. 505 Percussion Welding (PEW) .................................................................... 514 Plasma Arc Welding (PAW) .................................................................... 511 Magnetically Impelled Arc Welding ........................................................ 515 Welding Arc Technology ......................................................................... 517 Resistance Welding Processes .................................................................. 520 Resistance Spot Welding (RSW) ........................................................... 522 Projection Welding (PW) ........................................................................ 532 Upset Welding (UW) ............................................................................... 533 Flash Welding (FW) ................................................................................ 537 Electrical Metal-Explosion Welding Process .......................................... 541 Resistance Seam Welding (RSEW) ....................................................... 531 Induction Welding (IW) ........................................................................... 542 Electroslag Welding (ESW) .................................................................... 542 Welding in a High Vacuum (EBW-HV) ................................................... 550 Welding in a Medium Vacuum (EBW-MV) ............................................. 565 Electron Beam Welding (EBW) ................................................................... 548 Nonvacuum Electron Beam Welding (EBW-NV) .................................... 565 Tracking Joints During Electron Beam Welding ..................................... 565 Laser Beam Welding (LBW) ....................................................................... 568 Nature of Laser Beams and Plasma Generation ................................... 569 Basic Techniques in Laser Welding ....................................................... 571 Attributes of Laser Welding .................................................................... 571 Laser Welding Difficulties and Defects ................................................... 572 Shielding Gas Effects in Laser Welding ................................................. 575 Filler Wire Feeding in Laser Welding ..................................................... 576 Oxyfuel Welding (OFW) .............................................................................. 582 Oxyacetylene Welding (OAW) ............................................................... 582 Thermite Welding (TW) ............................................................................... 585 SOLID-STATE WELDING PROCESSES ....................................................... 587 Hot Pressure Welding (HPW) ..................................................................... 589 Induction Welding (IW) ................................................................................ 592 Friction Welding (FRW) ............................................................................... 593 Inertia-Drive Friction Welding ................................................................. 594 Direct-Drive Friction Welding .................................................................. 595 Materials Suited for Friction Welding ...................................................... 595 Other Forms of Friction Welding ............................................................ 600 Mechanical Properties of Friction Welds ................................................ 598 Explosion Welding (EXW) ........................................................................... 607 Diffusion Welding (DFW) ............................................................................ 612 Electrostatic Bonding .................................................................................. 617 Electrodeposition Welding ........................................................................... 619 BRAZING AND SOLDERING PROCESSES ................................................. 620 Brazing Processes (B) ................................................................................ 620 Soldering (S) ............................................................................................... 624 SURFACING BY WELDING AND THERMAL SPRAY ................................. 628 Buildup ........................................................................................................ 628 Buttering ...................................................................................................... 628 Hardfacing ................................................................................................... 629 Overlaying and Cladding ............................................................................. 632 THERMAL CUTTING PROCESSES .............................................................. 633 Metallurgical Effects of Thermal Cutting ..................................................... 633 Oxygen Cutting Processes (OC) ................................................................ 634 Oxyfuel Gas Cutting (OFC) .................................................................... 635 Chemical Flux Cutting (FOC) ................................................................. 636 Metal Powder Cutting (POC) .................................................................. 636 Electric Arc Cutting Processes (AC) ........................................................... 637 Air Carbon Arc Gutting (CAGA) ............................................................. 639 Plasma Arc Cutting (PAC) ...................................................................... 640 Electron Beam Cutting (EBC) ..................................................................... 643 Laser Beam Cutting (LBC) .......................................................................... 647 SUGGESTED READING ................................................................................ 651 Ultrasonic Welding (USW) .......................................................................... 613 Cold Welding (CW) ..................................................................................... 616 Chapter Seven: Temperature Changes in Welding ........................................... 653 TERMS AND DEFINITIONS ......................................................................... 653 Heat ........................................................................................................... 653 Temperature .............................................................................................. 654 Thermal Flow ............................................................................................. 654 Conduction, Convection, and Radiation .................................................... 655 Enthalpy and Entropy ................................................................................ 656 TEMPERATURE AND TIME IN WELDING .................................................. 656 Heat Flow Equations ................................................................................. 657 Heat Source Characterization ................................................................... 658 Rate of Heating ......................................................................................... 659 Heating Potential of Energy Sources ........................................................ 661 OAW Heating Potential ......................................................................... 662 AW Heating Potential ............................................................................ 662 FRW Heating Potential ......................................................................... 662 LBW Heating Potential .......................................................................... 663 Electrical Resistance Heating Potential ................................................ 663 EBW Heating Potential ......................................................................... 663 Peak Temperatures ................................................................................... 664 Defining the Weld Zone ........................................................................ 665 Numerical Modeling of Temperatures ................................................... 666 Effects of Temperature Distribution on Cooling Rate ............................. 670 Special Considerations Regarding Temperature Distribution.. ............6. 72 Furnace Heating for Welding Simulation .............................................. 675 Temper Color as an Indicant ................................................................ 675 Resistance Heating for Welding Simulation .......................................... 676 Cooling Rate of Heated Zones .................................................................. 677 Correllation with Heat Input .................................................................. 677 Workpiece Pre-Weld Temperature ....................................................... 681 Influence of Travel Speed on Weld Zone Size ......................................... 686 Hardness/Microstructure/CooIingRate Relationship ................................. 693 Cooling End Points ............................................................................... 696 CONTROL OF TEMPERATURE IN FUSION WELDING ............................. 698 Predictive Diagrams for Fusion Welding Parameters ................................ 699 Mathematical Modeling of Fusion Welding ............................................... 699 Sensory Systems for Adaptive Control of Fusion Welding ......................... 701 Adaptive Control of Solid-state Welding Processes .................................. 703 SUGGESTED READING ................................................................................ 705 Temperature Distributions ......................................................................... 668 Time at Temperature ................................................................................. 674 Instantaneous Cooling Rate .................................................................. 683 Chapter Eight: Fluxes. Slags. and Gases for Shielding .............................. 708 OXIDATION OF IRON ................................................................................... 708 OXIDATION OF STEEL ................................................................................ 710 Carbon/Oxygen Reaction in Molten Steel ................................................. 710 Oxidation of Solid Steel ............................................................................. 713 PREVENTING OXIDATION DURING WELDING ......................................... 714 Shielding Slags .......................................................................................... 714 Fluxes ........................................................................................................ 716 Controlled Atmospheres ............................................................................ 717 Vacuum .................................................................................................... -718 Technique .................................................................................................. 720 Deoxidizers ................................................................................................ 721 Protective Surface Alloys .......................................................................... 721 Liquid Blankets .......................................................................................... 722 Carbon Arc Welding .................................................................................. 722 SHIELDING THE JOINING PROCESSE§ FROM AIR ................................ 722 Metal Arc Welding ..................................................................................... 723 Covered Electrodes .............................................................................. 724 Generic Electrode Coverings and Typical Formulas .............................. 731 Flux Cored Electrodes .......................................................................... 738 Submerged Arc Welding (SAW) ................................................................ 744 Types of SAW Fluxes and Their Classification ..................................... 744 Methods of Manufacturing SAW Fluxes ............................................... 748 Physical Chemistry of Fluxes in SAW Process ..................................... 750 Transfer of Elements Between SAW FluxlSlag and Weld Metal .......... 758 Electroslag Welding ................................................................................... 765 Gas Shielded Arc Welding ........................................................................ 766 Argon ..................................................................................................... 768 Helium ................................................................................................... 768 Carbon Dioxide ..................................................................................... 769 Propane ................................................................................................. 770 Nitrogen ................................................................................................. 770 Hydrogen ............................................................................................... 770 Miscellaneous Gas Additives ................................................................ 771 Gas Tungsten Arc Welding ....................................................................... 771 Gas Metal Arc Welding ............................................................................. 772 Globular Transfer in GMAW ................................................................. 775 Repelled Transfer in GMAW ................................................................. 775 Projected Transfer in GMAW ................................................................ 776 Streaming or Axial-Spray Transfer in GMAW ....................................... 776 Pulsed Spray Transfer in GMAW-P ...................................................... 777 Rotating Droplet (Kinking) Transfer in GMAW ...................................... 778 Explosive Drop Transfer in GMAW ....................................................... 778 Short Circuiting Transfer in GMAW-S ................................................... 778 Flux Cored Arc Welding (FCAW) .............................................................. 779 Plasma Arc Welding (PAW) ...................................................................... 780 Electrogas Welding (EGW) ....................................................................... 780 Laser Beam Welding (LBW) ................................................................. 781 Other Welding Processes Using Gas Shielding ........................................ 781 Non-Vacuum Electron Beam Welding (EBW-NV) .................................. 781 Protecting Brazing Processes From Air .................................................... 782 Soldering - Ways to Achieve Bonding .................................................... 784 Fluxes for Soldering .............................................................................. 784 Mechanical Means to Accomplish Solder Bonding ............................... 784 SUGGESTED READING .............................................................................. 785 Chapter Nine: Simple Welds in Iron and Steel ................................................. 787 FUSION WELDS ........................................................................................... 787 Solidification of Weld Metal ....................................................................... 788 Modes of Primary Solidification Structure ............................................. 793 The Weld Zone .......................................................................................... 797 The Unmixed Zone .................................................................................... 799 The Heat-Affected Zone ............................................................................ 801 Unaffected Base Metal .............................................................................. 802 The Partially Melted Zone ......................................................................... 800 SOLID-STATE WELDS ................................................................................. 802 MICROSTRUCTURAL TRANSFORMATIONS IN SOLID IRON AND STEEL ........................................................................................ 802 Phase Changes in Steel ............................................................................ 803 Ferrite .................................................................................................... 804 Austenite ............................................................................................... 804 Cementite .............................................................................................. 806 Pearlite .................................................................................................. 807 Widmanstätten Pattern ......................................................................... 809 Microstructures Formed in Steel During Cooling ....................................... 816 Martensitic Microstructures ................................................................... 818 Isothermal Transformation of Austenite .................................................... 824 Pearlite Formation Isothermally ............................................................ 826 Bainite Formation Isothermally ............................................................. 828 Martensite Formation ............................................................................ 828 Reappraisal of Microstructures Formed in Steel ........................................ 831 Upper Bainite ......................................................... ........................... 832 Lower Bainite ........................................................................................ 833 Importance of Delay-Time Before AusteniteTransformation ..................... 836 Martensite: Implications in Welding ........................................................... 836 Temperature Range for Martensite Formation ....................................... 837 Quantitative Prediction of Martensite Formation ................................... 839 Martensite Hardness Rationale ............................................................. 841 Martensite Formation Monitoring by AE Signals ................................... 842 IT Diagrams: Summation of Usefulness ................................................... 843 Microstructural Changes in Steel During Heating ...................................... 810 Importance of Critical Cooling Rate .......................................................... 834 Transformation of Austenite During Continuous Cooling ........................... 848 PREDICTION OF MICROSTRUCTURES IN THE HEAT-AFFECTED ZONES OF WELDS ...................................................................................... 851 Jominy Method of Predicting HAZ Microstructure ...................................... 852 Mathematical Approach to Prejudging HAZ Suitability ............................. 856 TRANSFORMATIONS IN WELD METAL .................................................... 857 Importance of Weld Metal Composition ................................................ 870 Role of Grain Size in Weld Metal .......................................................... 872 Influence of Nonmetallic Inclusions in Weld Metal ............................... 872 STUDY OF A TYPICAL FUSION WELD IN STEEL .................................... 876 The Challenge of Optimizing Welding Procedures ..................................... 888 Base Metal ............................................................................................ 889 Weld Metal ............................................................................................ 890 Welding Process and Procedure .......................................................... 890 Weldment Property Testing .................................................................. 890 Nondestructive Examination ................................................................. 890 SUGGESTED READING .............................................................................. 891 Appendixes ............................................................................................... 893 1 . ACRONYMS FOR ORGANIZATIONS ........................................................ 893 II . STANDARD TERMINOLOGY REFERENCES ........................................... 895 111 . SYMBOLS USED IN TEXT AND TABLES ............................................... 896 IV . ALPHABETS USED IN SCIENTIFIC NOTATION .................................... 896 V . ABBREVIATIONS & ALPHABETICAL DESIGNATIONS ......................... 897 VI . SI BASE UNITS ......................................................................................... 901 VI1 . STRESS CONVERSION: MPa w ksi ...................................................... 902 VIII . TEMPERATURE CONVERSION: CELSIUS e FAHRENHEIT ............. 905 IX . THE ELEMENTS: SYMBOLS & PROPERTIES ....................................... 907 X . THE ELEMENTS: ELECTRON CONFIGURATIONS ................................ 913 XI . ELECTRONIC DATABASES & COMPUTER PROGRAMS .................... 919 Index .............................................................................................................. 923
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Welding Metallurgy - Volume1
Language: english
Author: George E. Linnert
Genre: Textbook
Publisher: GML Publications
Edition: 4th
ISBN: 0-8717 1-457-4
Format: PDF
Quality: eBook
Pages count: 963
Description: Readers of Welding Metallurgy in their comments about previous Volumes 1 and
2 of the Third Edition have offered helpful suggestions toward betterment of future
editions. All offerings from students, engineers, experienced welding personnel, and
educators have been carefully weighed by the author in planning this present revision.
A principal aim in carrying out this work was to acquire updated information wherever
available, but input from readers prompted several changes. One change will be
found in the sequence of chapters, which now provides more logical progression from
the structures and properties of metals, through the mechanics and effects of heating
for welding, and finally to metallurgical description of typical welds in steel. Also, the
remodeled text now includes additional material of a fundamental nature to assist in
developing broader, analytical explanations for the chemical and physical events that
arise in welding. The need for this assistance had been voiced by readers who are confronted
with the complex technology of welding, but who have not had exposure to
chemistry and physics of the depth needed to rationalize the phenomena encountered.
Relationships between fundamental features of metals and their behavior in welding
are pointed out to encourage development of more complete understanding of each
particular happening in welding. This kind of awareness of the factors involved and
the mechanics entailed aids greatly when a decision must be made regarding the most
effective measure for dealing with a given troublesome situation.
Contents
Chapter One:Background to Welding Metallurgy ............................................ 1
MILESTONES IN WELDING HISTORY ........................................................... 1
THE FUTURE OF WELDING ............................................................................ 4
WHAT IS WELDING METALLURGY? ............................................................. 6
PUTTING WELDING METALLURGY TO USE .............................................. 12
WELDING TECHNOLOGY RESOURCES .................................................... -12
SUGGESTED READING ................................................................................ 15
Chapter Two:
The Structure of Metals ..................................................................... 18
ATOMS ............................................................................................................ 18
Elementary Particles ................................................................................... 20
Electrons ................................................................................................. 22
Positrons ................................................................................................. 26
Protons .................................................................................................... 27
Ne ut rons .................................................................................................. 28
Atom Construction ....................................................................................... 32
Isotopes of Elements .............................................................................. 33
Isobars .................................................................................................... 34
Atomic Weight ......................................................................................... 34
Atomic Mass ........................................................................................... 34
Atom Valency .......................................................................................... 35
Ionization ................................................................................................. 36
Radioactivity ............................................................................................ 37
Atom Size or Diameter ............................................................................ 38
THE ELEMENTS ............................................................................................. 39
AGGREGATES OF ATOMS ........................................................................... 41
The Solid State ............................................................................................ 45
The Crystalline Solids ............................................................................. 45
Amorphous Solids ................................................................................... 47
The Liquid State .......................................................................................... 48
The Gaseous State ..................................................................................... 49
FUNDAMENTALS OF CRYSTALS ................................................................ 50
Identification of Planes and Directions in Crystals ...................................... 56
Basic Types of Crystals ............................................................................... 56
Inert Gas Crystals ................................................................................... 58
Covalent Crystals. ................................................................................... 59
Ionic Crystals .......................................................................................... 58
Metallic Crystals ...................................................................................... 59
THE CRYSTALLINE STRUCTURE OF METALS ........................................... 61
How Does a Crystal Grow from the Melt? .................................................. 64
The Formation of Dendrites ....................................................................... -66
The Formation of Grains ............................................................................. 68
The Shape of Grains ............................................................................... 71
The Size of Grains .................................................................................. 72
Undercooling ............................................................................................... 72
THE IMPORTANCE OF A CRYSTALLINE STRUCTURE ............................. 74
Allotropic Transformation ............................................................................ 75
Solubility in the Solid State ......................................................................... 76
Slip in Crystalline Structures ................................................................... 77
Slip and Lattice Orientation ..................................................................... 78
Slip in Polycrystalline Metals .................................................................. 79
Observing Slip ......................................................................................... 80
Twinning in Crystalline Structures .......................................................... 81
Lattice Imperfections: Dislocations .............................................................. 84
Point Defects ........................................................................................... 85
Edge Dislocations ................................................................................... 86
Screw Dislocations .................................................................................. 88
Stacking Faults ....................................................................................... 88
Other Lattice Imperfections ..................................................................... 88
Cold-Working Metals ................................................................................... 88
EXAMINATION OF METAL STRUCTURES .................................................. 91
Fracture Appearance Assessment .............................................................. 92
Metallography .............................................................................................. 92
Metallography Using Optical Microscopy ................................................ 92
Quantitative Metallography .................................... ........................... 105
Metallography Using the Electron Microscope ....... ........................... 106
Metallography Using Ion Microscopy .................................................... 115
Tunnel-Effect Microscopy ..................................................................... 116
... 116
........................................... 121
FRACTOGRAPHY ........................................................................................ 123
SUGGESTED READING .............................................................................. 131
Plasticity in Metallic Crystals ....................................................................... 77
Chemical Analysis of Microstructural Constituents .....
Newer Techniques in Metallurgy ....
Chapter Three:
The Properties of Metals ................................................................ 133
STRUCTURE SENSITIVITY OF PROPERTIES ........................................... 133
DIRECTIONALITY IN PROPERTIES ............................................................ 135
MECHANICAL PROPERTIES ...................................................................... 136
Elastic Behavior of Metals ......................................................................... 137
Young's Modulus of Elasticity ............................................................... 139
Poisson's Ratio ..................................................................................... 139
Limits of Elasticity and Proportionality .................................................. 141
Plastic Yielding in Metals .......................................................................... 142
Yield Strength ....................................................................................... 143
Breaking Strength of Metals ...................................................................... 143
Tensile Strength .................................................................................... 144
True Stress and True Strain ................................................................. 144
Notched Tensile Strength ..................................................................... 147
Ductility ...................................................................................................... 147
Elongation ............................................................................................. 148
Reduction of Area ................................................................................. 149
Ductility Indications from Special Tests ................................................ 149
Hardness ................................................................................................... 149
Microhardness Testing .......................................................................... 151
Dynamic Hardness Testing ................................................................... 152
Scratch Hardness Testing ..................................................................... 153
Conversion of Hardness Numbers ........................................................ 153
Toughness ................................................................................................. 154
Introduction of Impact Testing .............................................................. 155
FRACTURE IN METALS .............................................................................. 156
Ductile Fracture ......................................................................................... 158
Brittle Fracture ........................................................................................... 159
Intergranular Fracture ................................................................................ 162
Conditions Affecting Fracture Toughness ................................................. 164
Effect of Temperature ........................................................................... 164
Effect of Stress Axiality ......................................................................... 166
Stress Gradient ..................................................................................... 169
Stress Multiaxiality ................................................................................ 170
Effect of Rate of Strain .......................................................................... 171
Effect of Cyclic Stress (Fatigue) ................................................................ 174
Fatigue Crack Initiation ......................................................................... 176
Fatigue Crack Propagation ................................................................... 176
Cyclic Stress Limits to Avoid Fatigue Failure ....................................... 181
Cyclic Stress Conditions ....................................................................... 183
Variable Loading and Cumulative Fatigue Damage .............................. 185
FRACTURE MECHANICS: ASSESSMENT OF FRACTURE
TOUGHNESS .................................................................................................. 188
Brittle Fracture Test Parameters ................................................................. 190
Section Dimensions ................................................................................ 192
Plotting Coordinates ............................................................................... 192
Crack Surface Displacement Mode ........................................................ 193
Plane-Strain ............................................................................................ 195
Plane-Stress ........................................................................................... 195
Stress Distribution ................................................................................... 196
Use of Linear-Elastic Fracture Mechanics ................................
Crack Tip Opening Displacement Testing ................................
The J-Integral Test Method ......................................................
Procedures for Evaluating Propensity for Brittle Fracture ............
Development of Elastic-Plastic Fracture Mechanics .................................. 201
Fatigue Cracking Assessment by Fracture Mechanics .............................. 215
Mechanical Properties at Low Temperature ............................................... 218
Strength at Low Temperature ................................................................. 219
Test Methods for Toughness Evaluation ................................................ 226
Correlation of Results from Fracture Toughness Tests ......................... 236
Improved Mechanical Properties for Low-Temperature Service ................ 238
Impact Toughness at Low Temperature ................................................ 220
Mechanical Properties at Elevated and High Temperatures. ..................... 238
Short-Time Elevated Temperature Testing ............................................ 241
Long-Time Elevated Temperature Testing ............................................. 242
Mechanical Properties After Plastic Work ................................................... 247
Hot Work ................................................................................................. 248
Cold Work ............................................................................................... 248
Peening ................................................................................................... 248
Irradiation ................................................................................................ 249
PHYSICAL PROPERTIES .............................................................................. 258
Density ........................................................................................................ 258
Thermal Properties ........................................................... ....................... 259
Specific Heat ........................................................................................... 260
Thermal Conductivity .............................................................................. 261
Melting Point or Melting Range .............................................................. 264
Heat of Fusion ........................................................................................ 264
Viscosity and Surface Tension of Molten Metals ................................... 264
Boiling Point and Heat of Vaporization ................................................... 266
Thermal Expansion and Contraction ...................................................... 266
Thermionic Work Function ... ............................................................... 268
Electrical Properties .................................................................................... 268
Magnetic Properties .................................................................................... 270
Evaluation of Magnetization ................................................................... 272
Summary of Magnetic Behavior ............................................................. 273
Involvement of Magnetization in Welding ............................................... 274
CHEMICAL PROPERTIES ............................................................................. 274
Corrosion of Metals ..................................................................................... 275
Corrosion in Aqueous Solutions ............................................................. 276
Corrosion in Hot Gases .......................................................................... 282
Corrosion in Molten Metals ..................................................................... 282
Corrosion in Molten Salt ......................................................................... 283
Forms of Corrosion Pertinent to Weldments .............................................. 283
Stress Corrosion Cracking (SCC) .......................................................... 284
SUGGESTED READING ................................................................................ 293
Chapter Four:
Effects of Alloying Elements ....................................................... 295
ALLOYING .................................................................................................... 295
Alloys in the Liquid State ........................................................................... 296
Phase Diagrams ........................................................................................ 299
Binary Phase Diagrams ........................................................................ 304
Ternary Phase Diagrams ...................................................................... 307
Phase Diagrams for Multi-Element Alloys ............................................ 308
Alloys in the Solid State ............................................................................ 310
Factors Influencing Solid Solubility ....................................................... 310
Formation of Intermediate Phases and Compounds ............................. 316
Mechanisms and General Effects of Alloying ........................................... 316
Role of Crystalline Structure ................................................................. 317
Role of Microstructure ........................................................................... 319
Mechanisms for Altering Mechanical Properties ................................... 319
ALLOYING ELEMENTS IN IRON ................................................................. 326
Carbon ......................................................................................................... 329
Analysis of the Iron-Iron Carbide Diagram ............................................. 331
Manganese .................................................................................................. 337
Phosphorus ................................................................................................. 338
Sulfur and Selenium .................................................................................... 340
Si I icon .......................................................................................................... 342
Copper ......................................................................................................... 343
Chromium .................................................................................................... 345
Nickel ........................................................................................................... 346
Molybdenum ................................................................................................ 346
Niobium (Columbium) ................................................................................. 347
Vanadium .................................................................................................... 348
Alum i num .................................................................................................... 348
Nitrogen ....................................................................................................... 349
Titanium ....................................................................................................... 352
Boron ........................................................................................................... 354
Cobalt .......................................................................................................... 355
Tungsten ..................................................................................................... 355
Lead ............................................................................................................ 355
Other Alloying Elements ............................................................................. 356
BENEFIT OF REVERSING THE ALLOYING TREND ................................... 357
Residual Elements ...................................................................................... 358
SUGGESTED READING .............................................................................. 359
Chapter Five:
Types of Steel and Their Manufacture ................................. 361
GENERAL CATEGORIES OF IRON AND STEEL ....................................... 361
IRON PRODUCTION BY ORE REDUCTION ............................................... 362
Blast Furnace ............................................................................................ 362
Direct Reduction Processes ........................... ....................................... 365
CAST IRON ................................................................................................... 366
WROUGHT IRON .......................................................................................... 367
POWDER METALLURGY ............................................................................ 367
STEELMAKING PROCESSES ..................................................................... 368
Significance of Acid and Basic Steelmaking ............................................. 368
Bessemer Converter ................................................................................ 369
Open Hearth Furnace ............................................................................... 370
Rimmed Steel ....................................................................................... 372
Capped Steel ........................................................................................ 373
Killed Steel ............................................................................................ 373
Semikilled Steel .................................................................................... 379
Vacuum Deoxidized Steel ..................................................................... 379
Oxygen Steelmaking ................................................................................. 380
Sasic Oxygen Steelmaking ..................................................
L-D Process .....................................................................
Kaldo Process ....................................................................................... 383
Off-Gas BOF ......................................................................................... 383
Q-BOP Process .................................................................................... 383
Lance-Bubbling-Equilibrium .................................................................. 385
Ladle Refining ........................................................................................... 385
Slag Removal ........................................................................................ 385
Mixing Capability ................................................................................... 386
Alloying Additions ............................. ........................................... 386
Vacuum Treatment .......................... ........................................... 386
Temperature Adjustment ................. ........................................... 387
Desu Ifu rization ...................................................................................... 388
Electric-Arc Furnace .................................................................................. 389
Electric-Induction Furnace ...................... ............................................... 389
Electroslag Remelting ............................................................................... 391
SPECIAL MELTING PROCESSES .............................................................. 392
. .
Vacuum Induction Melting ......................................................................... 392
Vacuum Consumable-Electrode Remelting .............................................. 393
Electron-Beam Melting .............................................................................. 395
Argon-Oxygen Decarburization (AOD) ...................................................... 396
FOUNDRY AND STEEL MILL OPERATIONS ............................................. 397
Ingot Steelmaking Practice ....................................................................... 398
Continuous Casting of Steel ...................................................................... 400
HOT WORKING OPERATIONS ................................................................... 404
Thermo-Mechanical Control Process (T-MCP) ......................................... 406
COLD FINISHING ......................................................................................... 407
HEAT TREATMENT ...................................................................................... 408
CONTINUOUS COATING OF STRIP STEEL IN COILS .............................. 409
TYPES OF STEEL ........................................................................................ 410
Carbon Steels ............................................................................................ 41 O
Alloy Steels ................................................................................................ 411
Construction .......................................................................................... 412
Low-Temperature Service ..................................................................... 413
Elevated Temperature Service ............................................................. 413
High-Alloy Steels ....................................................................................... 413
Austenitic Manganese Steel ................................................................. 413
Stainless Steels .................................................................................... 414
Heat-Resisting Steels ........................................................................... 415
Tool Steels ................................................................................................ 415
STANDARDS AND SPECIFICATIONS FOR STEELS ................................. 416
Unified Numbering System ....................................................................... 416
AISI-SAE System of Standard Carbon and Alloy Steels ........................... 418
ASTM Standards ....................................................................................... 420
API Specifications ..................................................................................... 424
Aerospace Material Specifications ............................................................ 426
ASME Material Specifications ................................................................... 426
AWS Specifications. Code6 and Rules ..................................................... 429
CARBON AND ALLOY STEEL USED IN WELDED CONSTRUCTION ...... 430
Qualities of Steel Important to Welding ..................................................... 431
Factors Affecting the Weldability of Steel ................................................. 432
Chemical Composition .......................................................................... 432
Mechanical Properties .......................................................................... 434
Metallurgical Structure .......................................................................... 435
Internal Soundness ............................................................................... 435
Cleanliness ............................................................................................ 436
THE FUTURE OF STEELS AND THEIR WELDABILI TY ............................. 437
New Steels and Product Forms ................................................................ 437
Dissimilar-Metal Welding ........................................................................... 437
Repair Welding - The Ultimate Challenge .............................................. 439
SUGGESTED READING .............................................................................. 439
Automotive. Aircraft. and Machinery ..................................................... 412
Chapter Six:
Welding Methods and Processes ............................................ 444
SOLID-STATE WELDING (SSW) ................................................................. 444
FUSION WELDING ......................................................................................... 445
BRAZING AND SOLDERING ......................................................................... 445
HEAT SOURCES FOR WELDING AND CUTTING ....................................... 448
Electrical Heat Generation .......................................................................... 448
Electric Arc .............................................................................................. 448
Electron Beam ........................................................................................ 459
Electric Resistance ...................................................................................... 461
Electromagnetic Radiation .......................................................................... 461
Laser Beams ........................................................................................... 463
Chemical Heat Generation .......................................................................... 465
Mechanical Heat Generation ...................................................................... 466
THE WELDING AND CUTTING PROCESSES ............................................. 467
Power Sources for Arc Welding ............................................................. 467
Auxiliary Equipment for Arc Welding ...................................................... 470
Basic Forms of Arc Welding ................................................................... 471
Stud Arc Welding (SW) ........................................................................... 477
Gas Tungsten Arc Welding (GTAW) ...................................................... 478
Gas Metal Arc Welding (GMAW) ............................................................ 489
Arc Welding Process ................................................................................... 467
Shielded Metal Arc Welding (SMAW) ..................................................... 472
Flux Cored Arc Welding (FCAW) ........................................................... 501
Submerged Arc Welding (SAW) ............................................................. 505
Percussion Welding (PEW) .................................................................... 514
Plasma Arc Welding (PAW) .................................................................... 511
Magnetically Impelled Arc Welding ........................................................ 515
Welding Arc Technology ......................................................................... 517
Resistance Welding Processes .................................................................. 520
Resistance Spot Welding (RSW) ........................................................... 522
Projection Welding (PW) ........................................................................ 532
Upset Welding (UW) ............................................................................... 533
Flash Welding (FW) ................................................................................ 537
Electrical Metal-Explosion Welding Process .......................................... 541
Resistance Seam Welding (RSEW) ....................................................... 531
Induction Welding (IW) ........................................................................... 542
Electroslag Welding (ESW) .................................................................... 542
Welding in a High Vacuum (EBW-HV) ................................................... 550
Welding in a Medium Vacuum (EBW-MV) ............................................. 565
Electron Beam Welding (EBW) ................................................................... 548
Nonvacuum Electron Beam Welding (EBW-NV) .................................... 565
Tracking Joints During Electron Beam Welding ..................................... 565
Laser Beam Welding (LBW) ....................................................................... 568
Nature of Laser Beams and Plasma Generation ................................... 569
Basic Techniques in Laser Welding ....................................................... 571
Attributes of Laser Welding .................................................................... 571
Laser Welding Difficulties and Defects ................................................... 572
Shielding Gas Effects in Laser Welding ................................................. 575
Filler Wire Feeding in Laser Welding ..................................................... 576
Oxyfuel Welding (OFW) .............................................................................. 582
Oxyacetylene Welding (OAW) ............................................................... 582
Thermite Welding (TW) ............................................................................... 585
SOLID-STATE WELDING PROCESSES ....................................................... 587
Hot Pressure Welding (HPW) ..................................................................... 589
Induction Welding (IW) ................................................................................ 592
Friction Welding (FRW) ............................................................................... 593
Inertia-Drive Friction Welding ................................................................. 594
Direct-Drive Friction Welding .................................................................. 595
Materials Suited for Friction Welding ...................................................... 595
Other Forms of Friction Welding ............................................................ 600
Mechanical Properties of Friction Welds ................................................ 598
Explosion Welding (EXW) ........................................................................... 607
Diffusion Welding (DFW) ............................................................................ 612
Electrostatic Bonding .................................................................................. 617
Electrodeposition Welding ........................................................................... 619
BRAZING AND SOLDERING PROCESSES ................................................. 620
Brazing Processes (B) ................................................................................ 620
Soldering (S) ............................................................................................... 624
SURFACING BY WELDING AND THERMAL SPRAY ................................. 628
Buildup ........................................................................................................ 628
Buttering ...................................................................................................... 628
Hardfacing ................................................................................................... 629
Overlaying and Cladding ............................................................................. 632
THERMAL CUTTING PROCESSES .............................................................. 633
Metallurgical Effects of Thermal Cutting ..................................................... 633
Oxygen Cutting Processes (OC) ................................................................ 634
Oxyfuel Gas Cutting (OFC) .................................................................... 635
Chemical Flux Cutting (FOC) ................................................................. 636
Metal Powder Cutting (POC) .................................................................. 636
Electric Arc Cutting Processes (AC) ........................................................... 637
Air Carbon Arc Gutting (CAGA) ............................................................. 639
Plasma Arc Cutting (PAC) ...................................................................... 640
Electron Beam Cutting (EBC) ..................................................................... 643
Laser Beam Cutting (LBC) .......................................................................... 647
SUGGESTED READING ................................................................................ 651
Ultrasonic Welding (USW) .......................................................................... 613
Cold Welding (CW) ..................................................................................... 616
Chapter Seven:
Temperature Changes in Welding ........................................... 653
TERMS AND DEFINITIONS ......................................................................... 653
Heat ........................................................................................................... 653
Temperature .............................................................................................. 654
Thermal Flow ............................................................................................. 654
Conduction, Convection, and Radiation .................................................... 655
Enthalpy and Entropy ................................................................................ 656
TEMPERATURE AND TIME IN WELDING .................................................. 656
Heat Flow Equations ................................................................................. 657
Heat Source Characterization ................................................................... 658
Rate of Heating ......................................................................................... 659
Heating Potential of Energy Sources ........................................................ 661
OAW Heating Potential ......................................................................... 662
AW Heating Potential ............................................................................ 662
FRW Heating Potential ......................................................................... 662
LBW Heating Potential .......................................................................... 663
Electrical Resistance Heating Potential ................................................ 663
EBW Heating Potential ......................................................................... 663
Peak Temperatures ................................................................................... 664
Defining the Weld Zone ........................................................................ 665
Numerical Modeling of Temperatures ................................................... 666
Effects of Temperature Distribution on Cooling Rate ............................. 670
Special Considerations Regarding Temperature Distribution.. ............6. 72
Furnace Heating for Welding Simulation .............................................. 675
Temper Color as an Indicant ................................................................ 675
Resistance Heating for Welding Simulation .......................................... 676
Cooling Rate of Heated Zones .................................................................. 677
Correllation with Heat Input .................................................................. 677
Workpiece Pre-Weld Temperature ....................................................... 681
Influence of Travel Speed on Weld Zone Size ......................................... 686
Hardness/Microstructure/CooIingRate Relationship ................................. 693
Cooling End Points ............................................................................... 696
CONTROL OF TEMPERATURE IN FUSION WELDING ............................. 698
Predictive Diagrams for Fusion Welding Parameters ................................ 699
Mathematical Modeling of Fusion Welding ............................................... 699
Sensory Systems for Adaptive Control of Fusion Welding ......................... 701
Adaptive Control of Solid-state Welding Processes .................................. 703
SUGGESTED READING ................................................................................ 705
Temperature Distributions ......................................................................... 668
Time at Temperature ................................................................................. 674
Instantaneous Cooling Rate .................................................................. 683
Chapter Eight:
Fluxes. Slags. and Gases for Shielding .............................. 708
OXIDATION OF IRON ................................................................................... 708
OXIDATION OF STEEL ................................................................................ 710
Carbon/Oxygen Reaction in Molten Steel ................................................. 710
Oxidation of Solid Steel ............................................................................. 713
PREVENTING OXIDATION DURING WELDING ......................................... 714
Shielding Slags .......................................................................................... 714
Fluxes ........................................................................................................ 716
Controlled Atmospheres ............................................................................ 717
Vacuum .................................................................................................... -718
Technique .................................................................................................. 720
Deoxidizers ................................................................................................ 721
Protective Surface Alloys .......................................................................... 721
Liquid Blankets .......................................................................................... 722
Carbon Arc Welding .................................................................................. 722
SHIELDING THE JOINING PROCESSE§ FROM AIR ................................ 722
Metal Arc Welding ..................................................................................... 723
Covered Electrodes .............................................................................. 724
Generic Electrode Coverings and Typical Formulas .............................. 731
Flux Cored Electrodes .......................................................................... 738
Submerged Arc Welding (SAW) ................................................................ 744
Types of SAW Fluxes and Their Classification ..................................... 744
Methods of Manufacturing SAW Fluxes ............................................... 748
Physical Chemistry of Fluxes in SAW Process ..................................... 750
Transfer of Elements Between SAW FluxlSlag and Weld Metal .......... 758
Electroslag Welding ................................................................................... 765
Gas Shielded Arc Welding ........................................................................ 766
Argon ..................................................................................................... 768
Helium ................................................................................................... 768
Carbon Dioxide ..................................................................................... 769
Propane ................................................................................................. 770
Nitrogen ................................................................................................. 770
Hydrogen ............................................................................................... 770
Miscellaneous Gas Additives ................................................................ 771
Gas Tungsten Arc Welding ....................................................................... 771
Gas Metal Arc Welding ............................................................................. 772
Globular Transfer in GMAW ................................................................. 775
Repelled Transfer in GMAW ................................................................. 775
Projected Transfer in GMAW ................................................................ 776
Streaming or Axial-Spray Transfer in GMAW ....................................... 776
Pulsed Spray Transfer in GMAW-P ...................................................... 777
Rotating Droplet (Kinking) Transfer in GMAW ...................................... 778
Explosive Drop Transfer in GMAW ....................................................... 778
Short Circuiting Transfer in GMAW-S ................................................... 778
Flux Cored Arc Welding (FCAW) .............................................................. 779
Plasma Arc Welding (PAW) ...................................................................... 780
Electrogas Welding (EGW) ....................................................................... 780
Laser Beam Welding (LBW) ................................................................. 781
Other Welding Processes Using Gas Shielding ........................................ 781
Non-Vacuum Electron Beam Welding (EBW-NV) .................................. 781
Protecting Brazing Processes From Air .................................................... 782
Soldering - Ways to Achieve Bonding .................................................... 784
Fluxes for Soldering .............................................................................. 784
Mechanical Means to Accomplish Solder Bonding ............................... 784
SUGGESTED READING .............................................................................. 785
Chapter Nine:
Simple Welds in Iron and Steel ................................................. 787
FUSION WELDS ........................................................................................... 787
Solidification of Weld Metal ....................................................................... 788
Modes of Primary Solidification Structure ............................................. 793
The Weld Zone .......................................................................................... 797
The Unmixed Zone .................................................................................... 799
The Heat-Affected Zone ............................................................................ 801
Unaffected Base Metal .............................................................................. 802
The Partially Melted Zone ......................................................................... 800
SOLID-STATE WELDS ................................................................................. 802
MICROSTRUCTURAL TRANSFORMATIONS IN SOLID
IRON AND STEEL ........................................................................................ 802
Phase Changes in Steel ............................................................................ 803
Ferrite .................................................................................................... 804
Austenite ............................................................................................... 804
Cementite .............................................................................................. 806
Pearlite .................................................................................................. 807
Widmanstätten Pattern ......................................................................... 809
Microstructures Formed in Steel During Cooling ....................................... 816
Martensitic Microstructures ................................................................... 818
Isothermal Transformation of Austenite .................................................... 824
Pearlite Formation Isothermally ............................................................ 826
Bainite Formation Isothermally ............................................................. 828
Martensite Formation ............................................................................ 828
Reappraisal of Microstructures Formed in Steel ........................................ 831
Upper Bainite ......................................................... ........................... 832
Lower Bainite ........................................................................................ 833
Importance of Delay-Time Before AusteniteTransformation ..................... 836
Martensite: Implications in Welding ........................................................... 836
Temperature Range for Martensite Formation ....................................... 837
Quantitative Prediction of Martensite Formation ................................... 839
Martensite Hardness Rationale ............................................................. 841
Martensite Formation Monitoring by AE Signals ................................... 842
IT Diagrams: Summation of Usefulness ................................................... 843
Microstructural Changes in Steel During Heating ...................................... 810
Importance of Critical Cooling Rate .......................................................... 834
Transformation of Austenite During Continuous Cooling ........................... 848
PREDICTION OF MICROSTRUCTURES IN THE HEAT-AFFECTED
ZONES OF WELDS ...................................................................................... 851
Jominy Method of Predicting HAZ Microstructure ...................................... 852
Mathematical Approach to Prejudging HAZ Suitability ............................. 856
TRANSFORMATIONS IN WELD METAL .................................................... 857
Importance of Weld Metal Composition ................................................ 870
Role of Grain Size in Weld Metal .......................................................... 872
Influence of Nonmetallic Inclusions in Weld Metal ............................... 872
STUDY OF A TYPICAL FUSION WELD IN STEEL .................................... 876
The Challenge of Optimizing Welding Procedures ..................................... 888
Base Metal ............................................................................................ 889
Weld Metal ............................................................................................ 890
Welding Process and Procedure .......................................................... 890
Weldment Property Testing .................................................................. 890
Nondestructive Examination ................................................................. 890
SUGGESTED READING .............................................................................. 891
Appendixes ............................................................................................... 893
1 . ACRONYMS FOR ORGANIZATIONS ........................................................ 893
II . STANDARD TERMINOLOGY REFERENCES ........................................... 895
111 . SYMBOLS USED IN TEXT AND TABLES ............................................... 896
IV . ALPHABETS USED IN SCIENTIFIC NOTATION .................................... 896
V . ABBREVIATIONS & ALPHABETICAL DESIGNATIONS ......................... 897
VI . SI BASE UNITS ......................................................................................... 901
VI1 . STRESS CONVERSION: MPa w ksi ...................................................... 902
VIII . TEMPERATURE CONVERSION: CELSIUS e FAHRENHEIT ............. 905
IX . THE ELEMENTS: SYMBOLS & PROPERTIES ....................................... 907
X . THE ELEMENTS: ELECTRON CONFIGURATIONS ................................ 913
XI . ELECTRONIC DATABASES & COMPUTER PROGRAMS .................... 919
Index .............................................................................................................. 923
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