Welding processes handbook

281 Pages·2012·26.41 MB·English

by  Klas Weman

Welding processes handbook

Welding processes
handbook
Second edition
Klas Weman
Oxford Cambridge Philadelphia New Delhi
Published by Woodhead Publishing Limited,
80 High Street, Sawston, Cambridge CB22 3HJ, UK
www.woodheadpublishing.com

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First edition 2003, Woodhead Publishing Limited and CRC Press LLC
Second edition 2012, Woodhead Publishing Limited
© Klas Weman and Liber AB, Stockholm, 2012
The author has asserted his moral rights.

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A catalogue record for this book is available from the British Library.

Library of Congress Control Number: 2011934935

ISBN 978-0-85709-510-7 (print)
ISBN 978-0-85709-518-3 (online)

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Printed by TJI Digital, Padstow, Cornwall, UK
Contents
Preface................................................................................................ ix
1 Introduction to welding.........................................................................1
The history of welding............................................................................................1
Terminology............................................................................................................7
References and further reading.............................................................................12
2 Gas welding......................................................................................... 13
Introduction...........................................................................................................13
Equipment.............................................................................................................13
Gas flames.............................................................................................................16
Welding techniques...............................................................................................17
Applications..........................................................................................................17
References and further reading.............................................................................18
3 Basics of electricity in welding .......................................................... 19
Introduction...........................................................................................................19
Basic electrical concepts.......................................................................................19
Components in electrical circuits..........................................................................22
Measuring welding data........................................................................................27
4 Arc welding: an overview.................................................................... 31
Introduction...........................................................................................................31
Arc physics............................................................................................................31
Drop transfer ........................................................................................................37
Magnetic arc blow.................................................................................................40
Shielding gases......................................................................................................43
Standardisation of shielding gases........................................................................44
Standards for wires and rods.................................................................................47
References and further reading.............................................................................50
5 Power sources for arc welding ........................................................... 51
Introduction...........................................................................................................51
Electrical characteristics and their control in welding..........................................51
Different types of welding power units.................................................................54
Controlling power sources....................................................................................57
Rating data for power sources...............................................................................59
Safety requirements...............................................................................................62
References and further reading.............................................................................62
6 TIG welding ......................................................................................... 63
Introduction...........................................................................................................63
Equipment.............................................................................................................63
v
CONTENTS
Consumables.........................................................................................................68
Quality issues........................................................................................................69
References and further reading.............................................................................69
7 Plasma welding....................................................................................71
Introduction...........................................................................................................71
Classification of plasma welding methods...........................................................72
Equipment.............................................................................................................73
Gases for plasma welding.....................................................................................74
References and further reading.............................................................................74
8 MIG/MAG welding.................................................................................75
Introduction...........................................................................................................75
Equipment.............................................................................................................76
Consumables.........................................................................................................82
MIG/MAG welding process variations.................................................................85
Quality issues in MIG/MAG welding...................................................................94
References and further reading.............................................................................97
9 Manual metal arc (MMA) welding with coated
electrodes ............................................................................................99
Introduction...........................................................................................................99
Equipment.............................................................................................................99
Consumables: electrodes.....................................................................................100
Quality issues......................................................................................................102
References and further reading...........................................................................103
10 Submerged arc welding .....................................................................105
Introduction.........................................................................................................105
Equipment...........................................................................................................106
Consumables.......................................................................................................110
Process knowledge..............................................................................................112
Quality issues: weld defects................................................................................115
References and further reading...........................................................................117
11 Pressure welding methods ................................................................119
Introduction.........................................................................................................119
Resistance welding..............................................................................................119
Friction welding..................................................................................................126
High-frequency welding and induction welding.................................................128
Ultrasonic welding..............................................................................................129
Explosion welding..............................................................................................129
Magnetic pulse welding......................................................................................130
Cold pressure welding.........................................................................................131
Diffusion welding...............................................................................................131
References and further reading...........................................................................132
12 Other methods of welding .................................................................133
Introduction.........................................................................................................133
vi
CONTENTS
Electroslag welding.............................................................................................133
Electrogas welding..............................................................................................134
Stud welding.......................................................................................................134
Laser welding......................................................................................................136
Electron beam welding........................................................................................139
Thermite welding................................................................................................141
References and further reading...........................................................................142
13 Cutting methods.................................................................................143
Introduction.........................................................................................................143
Thermal cutting...................................................................................................143
Water jet cutting..................................................................................................148
Thermal gouging.................................................................................................148
References and further reading...........................................................................149
14 Surface cladding and hardfacing methods........................................151
Introduction.........................................................................................................151
Types of wear......................................................................................................151
Thermal spraying................................................................................................153
References and further reading...........................................................................156
15 Mechanisation and robot welding......................................................157
Introduction.........................................................................................................157
Quality issues in mechanised welding................................................................157
Mechanised TIG welding....................................................................................158
Narrow-gap welding...........................................................................................160
Arc welding using robots....................................................................................161
References and further reading...........................................................................166
16 Soldering and brazing........................................................................167
Introduction.........................................................................................................167
Soldering.............................................................................................................168
Brazing................................................................................................................170
17 The welding environment and welding safety...................................175
Introduction.........................................................................................................175
Welding fumes and gases....................................................................................175
Electrical hazards................................................................................................177
Arc radiation.......................................................................................................179
Ergonomics.........................................................................................................180
Fire risks..............................................................................................................182
References and further reading...........................................................................184
18 Welding residual stress and distortion .............................................185
Introduction.........................................................................................................185
Residual stress.....................................................................................................185
Distortion............................................................................................................186
Reducing welding residual stress and distortion.................................................188
References and further reading...........................................................................189
vii
CONTENTS
19 The weldability of steel......................................................................191
Introduction.........................................................................................................191
Carbon steels.......................................................................................................191
High-strength steels............................................................................................195
Stainless steels....................................................................................................196
References and further reading...........................................................................206
20 Welding of aluminium ........................................................................207
Introduction.........................................................................................................207
Designation system for aluminium and filler materials......................................207
Weldability..........................................................................................................210
Suitable methods of welding aluminium............................................................213
Filler materials....................................................................................................214
Strength after welding ........................................................................................215
Quality issues in aluminium welding..................................................................218
References and further reading...........................................................................220
21 Design of welded components...........................................................221
Introduction.........................................................................................................221
Symbolic representation of welds on drawings..................................................221
Welding classes...................................................................................................224
Design considerations.........................................................................................225
Strength considerations of welded joints............................................................234
Analysis of statically loaded welded joints.........................................................235
Welded structures subjected to fatigue loads......................................................238
References and further reading...........................................................................242
22 Quality assurance and quality management .....................................245
Introduction.........................................................................................................245
Quality requirements for welding (EN ISO 3834)..............................................246
Welding coordination (EN ISO 14731)..............................................................247
Specification and qualification of welding procedures.......................................249
Qualification test of welders (EN 287-1)............................................................255
Non-destructive testing.......................................................................................257
References and further reading...........................................................................258
23 Welding costs.....................................................................................259
Introduction.........................................................................................................259
Some welding cost concepts...............................................................................259
Cost calculation...................................................................................................262
Mechanisation, automation, robot welding.........................................................265
24 Index...................................................................................................267
viii
Preface
Production of this guide to welding was originally prompted by a desire for an up-to-date
reference on applications in the field. The content has been chosen so that it can be used
as a textbook for European or International welding courses in accordance with guide-
lines from the European Federation for Welding, Joining and Cutting (EWF) and Inter-
national Institute of Welding (IIW). Over the last years, an equivalent Swedish guide has
been used for courses on welding processes and equipment. The author hopes that this
guide will serve as a useful reference book for those involved in the welding field.
In writing the book, there has been a conscious effort to ensure that both text and
illustrative material is clear, concentrating particularly on interesting and important
aspects.
Although the book has been written in Sweden, with input from Swedish experts, it
reflects technology and methods that are internationally accepted and used. My thanks
are due to all those who have been involved in the work, with particular mention to:
Claes Olsson, HighTech Engineering, who has written the chapter on design of
welded components.
Claes-Ove Pettersson, Sandvik, who has edited the section on stainless steel.
Curt Johansson, formerly SAQ, who has written the chapter on quality management.
Gunnar Lindén, Air Liquide, who has edited the chapter on welding costs.
Staffan Mattson, Aluminiumförlaget, who has written the chapter on welding of
aluminium.
Curt Johansson sadly died during preparation of this new edition. The book is dedi-
cated to him.
Klas Weman
ix