i

WeldingHandbook

Ninth Edition

Volume 1

WELDING SCIENCE AND TECHNOLOGY

Prepared under the direction of theWelding Handbook Committee

Cynthia L. JenneyAnnette O’Brien

Editors

American Welding Society

550 N.W. LeJeune RoadMiami, FL 33126

ii

Welding Handbook, Ninth Edition

Volume 1

Welding Science and Technology

Volume 2

Welding Processes—Part 1

Volume 3

Welding Processes—Part 2

Volume 4

Materials and Applications—Part 1

Volume 5

Materials and Applications—Part 2

iii

WeldingHandbook

Ninth Edition

Volume 1

WELDING SCIENCE AND TECHNOLOGY

American Welding Society

vii

CONTENTS

PREFACE............................................................................................................................................................. xiACKNOWLEGEMENTS .................................................................................................................................... xiiCONTRIBUTORS ............................................................................................................................................. xiii

CHAPTER 1—SURVEY OF JOINING, CUTTING, AND ALLIED PROCESSES

................................. 1Introduction .......................................................................................................................................................... 2Joining Processes ................................................................................................................................................... 3Cutting Processes................................................................................................................................................. 42Thermal Spraying ................................................................................................................................................ 47Conclusion .......................................................................................................................................................... 49Bibliography........................................................................................................................................................ 49Supplementary Reading List ................................................................................................................................ 50

CHAPTER 2—PHYSICS OF WELDING AND CUTTING

........................................................................ 51Introduction ........................................................................................................................................................ 52Fusion and Solid-State Welding ........................................................................................................................... 52Energy Sources for Welding ................................................................................................................................. 57Arc Characteristics .............................................................................................................................................. 67Metal Transfer..................................................................................................................................................... 73Melting Rates ...................................................................................................................................................... 78Physical Properties of Metals and Shielding Gases............................................................................................... 81Conclusion .......................................................................................................................................................... 84Bibliography........................................................................................................................................................ 84Supplementary Reading List ................................................................................................................................ 84

CHAPTER 3—HEAT FLOW IN WELDING

................................................................................................. 87Introduction ........................................................................................................................................................ 88Heat Flow Fundamentals..................................................................................................................................... 88Quantitative Calculation of Heat Transfer in Fusion Welding ............................................................................. 95Conduction of Heat during Fusion Welding ........................................................................................................ 97Convective Heat Transfer in the Weld Pool ....................................................................................................... 105Relative Importance of Conduction and Convection ......................................................................................... 108Conclusion ........................................................................................................................................................ 111Bibliography...................................................................................................................................................... 112Supplementary Reading List .............................................................................................................................. 113

CHAPTER 4—WELDING METALLURGY

................................................................................................ 115Introduction ...................................................................................................................................................... 116Physical Metallurgy ........................................................................................................................................... 116Metallurgy of Welding....................................................................................................................................... 130Weldability of Commercial Alloys ..................................................................................................................... 140Corrosion in Weldments .................................................................................................................................... 149The Brazed or Soldered Joint............................................................................................................................. 151Corrosion in Brazed and Soldered Joints ........................................................................................................... 154Conclusion ........................................................................................................................................................ 154Bibliography...................................................................................................................................................... 155Supplementary Reading List .............................................................................................................................. 155

CHAPTER 5—DESIGN FOR WELDING

................................................................................................... 157Introduction ...................................................................................................................................................... 158Properties of Metals .......................................................................................................................................... 158Weldment Design Program ................................................................................................................................ 166Welded Design Considerations ......................................................................................................................... 170

viii

Design of Welded Joints .....................................................................................................................................182Selection of Weld Type .......................................................................................................................................193Sizing of Steel Welds...........................................................................................................................................196Tubular Connections..........................................................................................................................................216Aluminum Structures .........................................................................................................................................226Conclusion .........................................................................................................................................................236Bibliography.......................................................................................................................................................237Supplementary Reading List...............................................................................................................................237

CHAPTER 6—TEST METHODS FOR EVALUATING WELDED JOINTS

..........................................239Introduction .......................................................................................................................................................240Testing for Strength............................................................................................................................................241Hardness Tests ...................................................................................................................................................256Bend Tests ..........................................................................................................................................................260Fracture Toughness Testing ................................................................................................................................261Fatigue Testing ...................................................................................................................................................272Corrosion Testing...............................................................................................................................................277Creep and Rupture Testing.................................................................................................................................280Testing of Thermal Spray Applications...............................................................................................................281Weldability Testing.............................................................................................................................................284Conclusion .........................................................................................................................................................292Bibliography.......................................................................................................................................................292Supplementary Reading List...............................................................................................................................294

CHAPTER 7—RESIDUAL STRESS AND DISTORTION

.......................................................................297Introduction .......................................................................................................................................................298Fundamentals.....................................................................................................................................................298Nature and Causes of Residual Stress.................................................................................................................300Effects of Residual Stress....................................................................................................................................308Measurement of Residual Stress .........................................................................................................................313Residual Stress Distribution Patterns..................................................................................................................318Effects of Specimen Size and Weight...................................................................................................................322Effects of Welding Sequence ...............................................................................................................................325Residual Stress in Welds Made with Different Welding Processes .......................................................................326Weld Distortion..................................................................................................................................................328Reducing or Controlling Residual Stress and Distortion.....................................................................................351Conclusion .........................................................................................................................................................354Bibliography.......................................................................................................................................................354Supplementary Reading List...............................................................................................................................356

CHAPTER 8—SYMBOLS FOR JOINING AND INSPECTION

.............................................................359Introduction .......................................................................................................................................................360Fundamentals.....................................................................................................................................................361Welding Symbols................................................................................................................................................361Welding Symbols for Specific Weld Types...........................................................................................................373Brazing Symbols.................................................................................................................................................381Soldering Symbols ..............................................................................................................................................382Inspection Symbols.............................................................................................................................................385Conclusion .........................................................................................................................................................393Bibliography.......................................................................................................................................................393Supplementary Reading List...............................................................................................................................393

CHAPTER 9—WELDMENT TOOLING AND POSITIONING

................................................................395Introduction .......................................................................................................................................................396Fixtures ..............................................................................................................................................................396

ix

Positioners......................................................................................................................................................... 403Conclusion ........................................................................................................................................................ 419Bibliography...................................................................................................................................................... 419Supplementary Reading List .............................................................................................................................. 419

CHAPTER 10—MONITORING AND CONTROL OF WELDING AND JOINING PROCESSES

.... 421Introduction ...................................................................................................................................................... 422Principles of Monitoring and Control................................................................................................................ 422Sensing Devices ................................................................................................................................................. 423Process Instrumentation .................................................................................................................................... 428Process Monitoring Systems .............................................................................................................................. 429Process Control Systems .................................................................................................................................... 429Monitoring and Control Systems....................................................................................................................... 431Conclusion ........................................................................................................................................................ 448Bibliography...................................................................................................................................................... 448Supplementary Reading List .............................................................................................................................. 448

CHAPTER 11—MECHANIZED, AUTOMATED, AND ROBOTIC WELDING

.................................... 451Introduction ...................................................................................................................................................... 452Mechanized Welding ......................................................................................................................................... 453Automated Welding........................................................................................................................................... 458Robotic Welding................................................................................................................................................ 467Planning for Automated and Robotic Welding .................................................................................................. 474Conclusion ........................................................................................................................................................ 482Bibliography...................................................................................................................................................... 482Supplementary Reading List .............................................................................................................................. 482

CHAPTER 12—ECONOMICS OF WELDING AND CUTTING

............................................................. 483Introduction ...................................................................................................................................................... 484The Cost Estimate ............................................................................................................................................. 484Economics of Welding ....................................................................................................................................... 485Automated and Robotic Systems ....................................................................................................................... 498Economics of Resistance Spot Welding .............................................................................................................. 510Capital Investment in Welding Automation and Robotics ................................................................................. 514Control of Welding Costs .................................................................................................................................. 517Economics of Brazing and Soldering.................................................................................................................. 523Economics of Thermal Cutting.......................................................................................................................... 530Conclusion ........................................................................................................................................................ 531Bibliography...................................................................................................................................................... 531Supplementary Reading List .............................................................................................................................. 531

CHAPTER 13—WELD QUALITY

.............................................................................................................. 533Introduction ...................................................................................................................................................... 534Defining Weld Quality ....................................................................................................................................... 534Overview of Weld Discontinuities...................................................................................................................... 536Discontinuities Associated with Fusion Welding ................................................................................................ 538Discontinuities Associated with Resistance Welding .......................................................................................... 562Discontinuities Associated with the Solid-State Welding Processes..................................................................... 567Discontinuities in Brazed and Soldered Joints.................................................................................................... 569Significance of Weld Discontinuities .................................................................................................................. 572Conclusion ........................................................................................................................................................ 575Bibliography...................................................................................................................................................... 576Supplementary Reading List .............................................................................................................................. 576

x

CHAPTER 14—WELDING INSPECTION AND NONDESTRUCTIVE EXAMINATION

...................579Introduction .......................................................................................................................................................580Personnel Qualifications.....................................................................................................................................581The Inspection Plan............................................................................................................................................583Nondestructive Examination..............................................................................................................................584Metallographic Examination Methods ...............................................................................................................633Inspection of Brazed and Soldered Joints............................................................................................................634Conclusion .........................................................................................................................................................634Bibliography.......................................................................................................................................................634Supplementary Reading List...............................................................................................................................636

CHAPTER 15—QUALIFICATION AND CERTIFICATION

....................................................................637Introduction .......................................................................................................................................................638Welding and Brazing Procedure Specifications....................................................................................................640Qualification of Welding and Brazing Procedures...............................................................................................655Performance Qualification..................................................................................................................................668Standardization of Qualification Requirements ..................................................................................................678Conclusion .........................................................................................................................................................679Bibliography.......................................................................................................................................................679Supplementary Reading List...............................................................................................................................680

CHAPTER 16—CODES AND OTHER STANDARDS

.............................................................................683Introduction .......................................................................................................................................................684Types of Regulatory Documents.........................................................................................................................684Standards-Developing Organizations and Welding-Related Publications............................................................685Guidelines for Participating in International Standards Activities.......................................................................708Conclusion .........................................................................................................................................................708Supplementary Reading List...............................................................................................................................709

CHAPTER 17—SAFE PRACTICES

...........................................................................................................711Introduction .......................................................................................................................................................712Safety Management............................................................................................................................................712Protection of the Work Area ..............................................................................................................................714Personal Protective Equipment ...........................................................................................................................719Protection against Fumes and Gases...................................................................................................................724Safe Handling of Compressed Gases ..................................................................................................................733Protection against Electromagnetic Radiation ....................................................................................................738Electrical Safety..................................................................................................................................................738Fire Prevention ...................................................................................................................................................741Explosion Prevention ..........................................................................................................................................743Process-Specific Safety Considerations ................................................................................................................743Safety in Robotic Operations .............................................................................................................................753Conclusion .........................................................................................................................................................754Bibliography.......................................................................................................................................................754Supplementary Reading List...............................................................................................................................757

APPENDIX A—TERMS AND DEFINITIONS

...........................................................................................759

APPENDIX B—METRIC PRACTICE GUIDE FOR THE WELDING INDUSTRY

..............................849

INDEX OF MAJOR SUBJECTS:Eighth Edition and Ninth Edition, Volume 1

.......................................................................................873

INDEX OF NINTH EDITION, Volume 1

...................................................................................................891

SURVEY OF JOINING, CUTTING,AND ALLIED PROCESSES

Prepared by theWelding Handbook Chapter Committee on Joining and Cutting Processes:

W. H. Kielhorn, Chair

LeTourneau University

Y. Adonyi

LeTourneau University

R. L. Holdren

Edison Welding Institute

R. C. Horrocks, Sr.

Springfield & Clark Company

N. E. Nissley

The Ohio State University

Welding Handbook Volume 1 Committee Member:

T. D. Hesse

Technical Welding Service

Contents

Introduction 2

Joining Processes 3

Cutting Processes 42

Thermal Spraying 47

Conclusion 49

Bibliography 49

SupplementaryReading List 50

CHAPTER 1

2

SURVEY OF JOINING, CUTTING, AND ALLIED PROCESSES

INTRODUCTION

CHAPTER 1

This chapter introduces the conventional and morewidely known joining, cutting, and thermal sprayingprocesses. The distinguishing features of the variousprocesses are summarized and compared to oneanother. Among the joining processes reviewed are thearc, resistance, and solid-state welding processes as wellas brazing, soldering, and adhesive bonding. The cut-ting processes examined include thermal and non-thermal methods. The thermal spraying processesconsidered include flame and plasma arc spraying aswell as arc and detonation flame spraying.

With respect to process selection, as several processesmay be applicable for a particular job, the challenge liesin selecting the process that is most suitable in terms offitness for service and cost. However, these factors maynot be compatible, thus forcing a compromise. Theselection of a process ultimately depends on several cri-teria. These include the number of components to befabricated, capital equipment costs, joint location,structural mass, and the desired performance of theproduct. The adaptability of the process to the locationof the operation, the type of shop, and the experienceand skill levels of the employees may also have animpact on the final selection. These criteria are exam-ined as they relate to the various joining, cutting, andthermal spraying processes.

As this chapter is intended to serve merely as a sur-vey of the most common joining, cutting, and thermal

spraying processes,

1

the reader is encouraged to con-duct a thorough investigation of the processes thatappear to have the best potential for the intended appli-cations. This investigation should take into accountsafety and health considerations such as those presentedin the American National Standard

Safety in Welding,Cutting, and Allied Processes,

ANSI Z49.1,

2, 3

and theinformation provided in the manufacturers’ materialsafety data sheets (MSDSs).

Additional sources of infor-mation about the joining, cutting, and allied processesare listed in the Bibliography and SupplementaryReading List at the end of this chapter. In particular,

Welding Processes,

4

Volume 2 of the American WeldingSociety’s

Welding Handbook

, 8th edition, presents in-

1. For further information on the categorization of the welding,joining, cutting, and allied processes, see Appendix A.2. At the time of the preparation of this chapter, the referenced codesand other standards were valid. If a code or other standard is citedwithout a date of publication, it is understood that the latest editionof the document referred to applies. If a code or other standard iscited with the date of publication, the citation refers to that editiononly, and it is understood that any future revisions or amendments tothe code or standard are not included; however, as codes and stan-dards undergo frequent revision, the reader is encouraged to consultthe most recent edition.3. American National Standards Institute (ANSI) Committee Z49 onSafety in Welding and Cutting,

Safety in Welding, Cutting, and AlliedProcesses

, ANSI Z49.1, Miami: American Welding Society.4. O’Brien, R. L., ed., 1991,

Welding Processes

, Vol. 2 of

WeldingHandbook

, 8th ed., Miami: American Welding Society.

SURVEY OFJOINING, CUTTING,AND ALLIEDPROCESSES

SURVEY OF JOINING, CUTTING, AND ALLIED PROCESSES

3

depth coverage of each of the welding, cutting, andallied processes.

JOINING PROCESSES

The goal of the joining processes is to cause diversepieces of material to become a unified whole. In the caseof two pieces of metal, when the atoms at the edge ofone piece come close enough to the atoms at the edge ofanother piece for interatomic attraction to develop, thetwo pieces become one. Although this concept is easy todescribe, it is not simple to effect. Surface roughness,impurities, fitting imperfections, and the varied proper-ties of the materials being joined complicate the joiningprocess. Welding processes and procedures have beendeveloped to overcome these difficulties by incorporat-ing the use of heat or pressure, or both. Though por-tions of this description do not apply to brazing,soldering, and adhesive bonding, an explanation will begiven when these processes are described later in thechapter.

Barring a few exceptions, most welding processesapply significant heat to the base material. This heat isonly a means to bring the atoms at the edge of one pieceof material close enough to the atoms of another piecefor interatomic attraction. However, this heat is detri-mental to the microstructure of the materials beingjoined. As hot metal tends to oxidize, sufficient protec-tion from oxidation must be provided by the weldingprocess to prevent this detrimental reaction with ambi-ent oxygen. Some metals are far more sensitive thanothers, in which case protection from oxidationbecomes more demanding. Thus, while examining eachwelding process, the reader should consider whetherheat is produced by the process and, if so, the mannerin which it is produced. The means by which sufficientprotection against oxidation is provided by the processshould then be identified.

The selection of an appropriate joining and cuttingprocess for a given task involves a number of consider-ations. These include the following:

1. Availability and fitness for service;2. Skill requirements;3. Weldability of the base metal alloy with respect

to type and thickness;4. Availability of suitable welding consumables;5. Weld joint design;6. Heat input requirements;7. Demands of the welding position;8. Cost of the process, including capital expendi-

tures, materials, and labor;9. Number of components being fabricated;

10. Applicable code requirements; and11. Safety concerns.

The overview of the joining processes featured inTable 1.1 presents an initial reference guide to the capa-bilities of various joining processes with respect to avariety of ferrous and nonferrous metals. This tableindicates the processes, materials, and material thick-ness combinations that are usually compatible. The col-umns on the left list various engineering materials andfour arbitrary thickness ranges. The processes mostcommonly used in industry are listed across the top.

It should be noted that additional information suchas the considerations listed above must be taken intoaccount before process selections are finalized. None-theless, Table 1.1 serves as a useful tool in providinggeneral guidelines for the screening and selectionprocess.

ARC WELDING

The term

arc welding

applies to a large, diversifiedgroup of welding processes that use an electric arc asthe source of heat. The creation of a weld between met-als using these processes does not usually involve pres-sure but may utilize a filler metal. The arc is struckbetween the workpiece and the tip of the electrode. Theintense heat produced by the arc quickly melts a por-tion of the base metal, resulting in the formation of aweld. The arc welding processes may be moved alongthe joint to produce the weld or held stationary whilethe workpiece is moved under the process.

Arc welding operations are performed by conductingthe welding current through consumable electrodes,which take the form of a wire or rod, or nonconsum-able electrodes, consisting of carbon or tungsten rods.Metal arc processes utilize consumable electrodes thatcombine electrode filler metal with the molten basemetal to create the weld. They may also produce a slagcovering to protect the molten metal from oxidation.The nonconsumable arc processes can generate a weldby melting the base metal only, resulting in what istermed an

autogenous weld

. If filler metal is required ina nonconsumable process, it may be fed either manuallyor mechanically into the molten weld pool. In this case,the nonconsumable electrode serves only to sustain thearc.

Shielded Metal Arc Welding

Illustrated in Figure 1.1, shielded metal arc welding(SMAW) is a basic, versatile process used to weld fer-rous and some nonferrous metals. The most widelyknown of the arc welding processes, shielded metal arcwelding is sometimes referred to colloquially as

stick

4

SURVEY OF JOINING, CUTTING, AND ALLIED PROCESSES

Table 1.1Capabilities of the Commonly Used Joining Processes

Material Thickness

†

Processes

*

SMAW

SAW

GMAW

FCAW

GTAW

PAW

ESW

EGW

RW

FW

OFW

DFW

FRW

EBW

LBW

TB

FB

RB

IB

DB

IRB

DFB S

Carbon steel

S x

‡

x x x x x x x x x x x x x x x xI x x x x x x x x x x x x x x x x x x x

M x x x x x x x x x x x x x xT x x x x x x x x x x x x

Low-alloy steel

S x x x x x x x x x x x x x x x x x xI x x x x x x x x x x x x x x x x

M x x x x x x x x x x x x x xT x x x x x x x x x x x

Stainless steel

S x x x x x x x x x x x x x x x x x x xI x x x x x x x x x x x x x x x x x

M x x x x x x x x x x x x x xT x x x x x x x x x x x

Cast iron I x x x x x x xM x x x x x x x x x xT x x x x x x x

Nickel and alloys

S x x x x x x x x x x x x x x x x xI x x x x x x x x x x x x x x x

M x x x x x x x x x x xT x x x x x x x x

Aluminum and alloys

S x x x x x x x x x x x x x x x x x x xI x x x x x x x x x x x x x x

M x x x x x x x x x xT x x x x x x x x

Titanium and alloys

S x x x x x x x x x x x xI x x x x x x x x x

M x x x x x x x x xT x x x x x x x x

Copper and alloys

S x x x x

§

x x x x x x x xI x x x x x x x

M x x x x xT x x x x

Magnesiumand alloys

S x x x x x x x x xI x x x x x x x x x x

M x x x x x xT x x

Refractory alloys

S x x x x x x x x x x x xI x x x x x x x x

M xT

* SMAW = shielded metal arc welding; SAW = submerged arc welding; GMAW = gas metal arc welding; FCAW = flux cored arc welding; GTAW = gas tungstenarc welding; PAW = plasma arc welding; ESW = electroslag welding; EGW = electrogas welding; RW = resistance welding; FW = flash welding; OFW = oxyfuelgas welding; DFW = diffusion welding; FRW = friction welding; EBW = electron beam welding; LBW = laser beam welding; TB = torch brazing; FB = furnacebrazing; RB = resistance brazing; IB = induction brazing; DB = dip brazing; IRB = infrared brazing; DB = diffusion brazing; and S = soldering.

†

S = sheet (up to 1/8 inch [in.] 3 millimeters [mm]); I = intermediate (1/8 in. to 1/4 in. [3 mm to 6 mm]); M = medium (1/4 in. to 3/4 in. [6 mm to 19 mm]);T = thick (3/4 in. [19 mm] and up).

‡

Commercial process.

§

Copper requires molybdenum-coated tips.