New developments in advanced welding

299 Pages·1.58 MB·English

by  Nasir Ahmed

Advanced welding processes
Related titles:
New developments in advanced welding
(ISBN-13: 978-1 85573-970-3; ISBN-10: 1-85573-970-4)
Recent developments in high-technology areas have significantly transformed the
welding industry where automation, computers, process control, sophisticated scientific
instruments and advanced processing methods are all common. Today’s engineers and
technologists have to support complex systems and apply sophisticated welding
technologies. This comprehensive book discusses the changes in advanced welding
technologies, preparing the reader for the modern industry.
MIG welding guide
(ISBN-13: 978-1-85573-947-5; ISBN-10: 1-85573-947-X)
Gas metal arc welding (GMAW), also referred to as MIG (metal inert gas) welding, is
one of the key processes in industrial manufacturing. The MIG welding guide provides
comprehensive, easy-to-understand coverage of this widely used process. The reader
is presented with a variety of topics from the choice of shielding gases, filler materials,
welding equipment and lots of practical advice. The book provides an overview of new
developments in various processes such as: flux-cored arc welding; new high-productive
methods; pulsed MIG welding; MIG-brazing; robotic welding applications and
occupational health and safety. This will be essential reading for welding engineers,
production engineers, designers and all those involved in industrial manufacturing.
Cumulative damage of welded joints
(ISBN-13: 978-85573-938-3; ISBN-10: 1-85573-938-0)
Fatigue is a mechanism of failure that involves the formation of cracks under the action
of different stresses. Fatigue cracks are exceedingly difficult to see, particularly in the
early stages of crack growth. Cracks can progress to a significant extent before they are
even discovered. To avoid fatigue it is essential to recognise at the design stage that the
loading is such that fatigue may be a possibility and to design the structure with inherent
fatigue strength. However, fatigue strength is not a constant material property. It may
be assessed by fracture mechanics, but such characteristics are based on quantitative
analysis and mere assumption. This book is primarily concerned with fatigue under
variable amplitude loading, unlike most tests performed under constant loads.
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For further information visit www.maney.co.uk/journals.
Advanced welding
processes
Technologies and process control
John Norrish
Woodhead Publishing and Maney Publishing
on behalf of
The Institute of Materials, Minerals & Mining
W
OODHEAD PUBLISHING LIMITED
Cambridge, England
Woodhead Publishing Limited and Maney Publishing Limited on behalf of
The Institute of Materials, Minerals & Mining
Woodhead Publishing Limited, Abington Hall, Abington, Cambridge CB1 6AH, England
www.woodheadpublishing.com
First published 1992, IOP Publishing Ltd
This edition 2006, Woodhead Publishing Limited
© Institute of Materials, Minerals & Mining, 2006
The author has asserted his moral rights.
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British Library Cataloguing in Publication Data
A catalogue record for this book is available from the British Library.
ISBN-13: 978-1-84569-130-1 (book)
ISBN-10: 1-84569-130-X (book)
ISBN-13: 978-1-84569-170-7 (e-book)
ISBN-10: 1-84569-170-9 (e-book)
Thepublisher’s policy is tousepermanentpaper from mills that operate a
sustainable forestry policy, and which has beenmanufacturedfrompulp
which is processed usingacid-free andelementarychlorine-free practices.
Furthermore, the publisher ensures that the text paper and cover board used
havemet acceptable environmental accreditation standards.
Typeset by Replika Press Pvt Ltd, India
Printed by T J International Limited, Padstow, Cornwall, England
Contents
Preface ix
Acknowledgements xi
1 An introduction to welding processes 1
1.1 Introduction 1
1.2 Conventional welding processes 2
1.3 Summary 15
2 Advanced process development trends 16
2.1 Introduction 16
2.2 Safety and environmental factors 21
2.3 Skill and training requirements 21
2.4 Areas for development 21
2.5 Process application trends 22
2.6 Summary 25
3 Welding power source technology 26
3.1 Introduction 26
3.2 Basic power source requirements 26
3.3 Conventional power source designs 27
3.4 Electronic power regulation systems 31
3.5 Output level, sequence and function control 39
3.6 Practical implications of electronic power regulation and
control 42
3.7 Summary 43
4 Filler materials for arc welding 44
4.1 Introduction 44
4.2 MMAW consumables 44
4.3 Submerged arc welding consumables 46
v
vi Contents
4.4 Filler wires for GMAW and FCAW 47
4.5 Summary 57
5 Gases for advanced welding processes 58
5.1 Introduction 58
5.2 Shielding gases for arc welding processes 58
5.3 Gases for laser welding 71
5.4 Summary 72
6 Advanced gas tungsten arc welding 74
6.1 Introduction 74
6.2 Process developments 74
6.3 Process variants 79
6.4 Control of GTAW and related processes 91
6.5 Summary 98
7 Gas metal arc welding 100
7.1 Introduction 100
7.2 Metal transfer in GMAW 100
7.3 The physics of metal transfer 110
7.4 Summary: metal transfer phenomena 113
7.5 Control of conventional GMAW 113
7.6 Summary: process control 120
7.7 Recent developments in the GMAW process 120
7.8 Summary 134
8 High-energy density processes 136
8.1 Introduction 136
8.2 Plasma keyhole welding 138
8.3 Laser welding 144
8.4 Electron beam welding 157
8.5 Summary 164
9 Narrow-gap welding techniques 165
9.1 Introduction 165
9.2 Principles and features of narrow-gap welding 165
9.3 Narrow-gap welding processes 166
9.4 Summary and implications 177
10 Monitoring and control of welding processes 179
10.1 Introduction 179
10.2 Manual control techniques 180
10.3 Monitoring 188
Contents vii
10.4 Automated control techniques 203
10.5 Summary and implications 216
11 Welding automation and robotics 218
11.1 Introduction 218
11.2 Automation options 219
11.3 Simple mechanization 219
11.4 Dedicated and special-purpose automation 223
11.5 Robotic welding 225
11.6 Modular automation 236
11.7 Programmable control 236
11.8 Remote-control slave and automated systems 237
11.9 Advances in welding automation 238
11.10 Evaluation of and justification for automated welding 242
11.11 Summary 246
Appendices 247
Appendix 1: Welding processes classification 249
Appendix 2: Shielded metal arc welding (SMAW) electrode
classification 250
Appendix 3: Burn-off characteristics 254
Appendix 4: American, Australian and European FCAW
classification systems 257
Appendix 5: Flux-cored wire for surfacing and wear
resistance 260
Appendix 6: Plasma keyhole welding parameters 262
Appendix 7: Plasma keyhole welding of titanium 263
References 265
Index 279

Preface
Welding has traditionally been regarded as a craft rather than a technological
manufacturing process. This reputation has not been helped by the dependence
of conventional joining techniques on highly skilled manual operators and the
relatively high cost and poor reproducibility associated with many welding
processes. These attributes led to the ‘Special Process’ classification of welding
in international quality standards. In fact, although it may be a complex multi-
disciplinary subject, a great deal of high-quality research has been conducted
into the fundamentals of welding processes and the basic principles are now
well understood. This research has provided a scientific basis for significant
developments in the technology.
Early developments in welding technology were focused largely on
weldability and metallurgical research, which enabled a wide range of materials
to be joined, adequate joint properties to be maintained and the integrity of
welded joints to be controlled. Whilst further work is still required in the
materials research area, in particular to enable advanced materials to be joined
effectively, much of the recent effort has been devoted to improved
understanding of the basic processes, consumable and equipment development
and control and automation.
John Norrish
University of Wollongong