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 Woodhead Publishing, 1518 Walnut Street, Suite 1100, Philadelphia, PA 19102-3406, USA Woodhead Publishing India Private Limited, G-2, Vardaan House, 7/28 Ansari Road, Daryaganj, New Delhi – 110002, India www.woodheadpublishingindia.com 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. This book contains information obtained from authentic and highly regarded sources. Reprinted material is quoted with permission, and sources are indicated. 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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