EXPLOSIVE WELDING, FORMING AND COMPACTION

EXPLOSIVE WELDING, FORMING AND COMPACTION

Edited by

T.Z.BLAZYNSKI

Department of Mechanical Engineering, The University of Leeds, UK

APPLIED SCIENCE PUBLISHERS LONDON and NEW YORK

APPLIED SCIENCE PUBLISHERS LTD Ripple Road, Barking, Essex, England

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British Library Cataloguing in Publication Data

Explosive welding, forming and compaction. l. Explosive welding I. Blazynski, T. Z. 671.5'2 TS227

ISBN 978-94-011-9753-3 ISBN 978-94-011-9751-9 (eBook) DOl 10.1007/978-94-011-9751-9

WITH 16 TABLES AND 156 ILLUSTRATIONS

© APPLIED SCIENCE PUBLISHERS LTD 1983

SOFTCOVER REPRINT OF THE HARDCOVER I ST EDITION 1983

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PREFACE

The last two decades have seen a steady and impressive development, and eventual industrial acceptance, of the high energy-rate manufact­turing techniques based on the utilisation of energy available in an explo­sive charge. Not only has it become economically viable to fabricate complex shapes and integrally bonded composites-which otherwise might not have been obtainable easily, if at all-but also a source of reasonably cheap energy and uniquely simple techniques, that often dispense with heavy equipment, have been made available to the engineer and applied scientist.

The consolidation of theoretical knowledge and practical experience which we have witnessed in this area of activity in the last few years, combined with the growing industrial interest in the explosive forming, welding and compacting processes, makes it possible and also opportune to present, at this stage, an in-depth review of the state of the art.

This book is a compendium of monographic contributions, each one of which represents a particular theoretical or industrial facet of the explosive operations. The contributions come from a number of practising engineers and scientists who seek to establish the present state of knowledge in the areas of the formation and propagation of shock and stress waves in metals, their metallurgical effects, and the methods of experimental assessment of these phenomena. On the manufacturing side, the contributors are concerned to explain the mechanisms of explosive forming, welding and powder compaction, and to indicate both the operational problems that may exist and the practical opportunities and advantages that these processes offer.

The purpose of the book as a whole is to provide the existing 'practitioner' with, perhaps, more detailed and yet, at the same time, wider knowledge of his field, and to indicate to the 'newcomer' what it is that he can expect to encounter in his work. It is with a view to the

v

vi PREFACE

particular needs of the latter that each chapter contains an extensive list of references which in themselves form valuable sources of further information.

Finally, I would like to express my thanks to the authors of individual chapters for their contributions and especially to Mr John Pearson who as one of the original pioneers of the explosive processes has brought so much of his personal experience to the writing of the introductory chapter.

T. Z. BLAZYNSKI

CONTENTS

Preface

List of Contributors.

l. Introduction to High-energy-rate Metalworking JOHN PEARSON .

l.l. Background 1.2. High-energy-rate Processes

1.2.1. Operation Concepts 1.2.2. Basic Types of Operations 1.2.3. Nature of Load Application .

1.3. Development of the Field . 1.3.1. Early Studies. 1.3.2. Explosive Forming 1.3.3. Explosive Hardening 1.3.4. Explosive Compaction 1.3.5. Explosive Welding.

1.4. Continued development of the field 1.4.1. Cooperative Effort. 1.4.2. Thoughts for the Future

References

2. Propagation of Stress Waves in Metals M.A. MEYERS and L. E. MuRR

v

XIII

1 2 2 3 4 5 5 6 8 9

10 12 12 12 14

17

2.1. Dynamic Propagation of Deformation 17 2.2. Elastic Waves . 21

2.2.1. Introduction . 21 2.2.2. Elastic Waves in Isotropic Materials 22 2.2.3. Elastic Waves in Anisotropic Media 27

2.3. Plastic Waves 30 2.3.1. Preliminary Considerations . 30 2.3.2. The von Karman and Duwez Plastic Wave Theory 32 2.3.3. Plastic Shear Waves 35

vii

viii CONTENTS

2.3.4. Additional Considerations on Plastic Waves. 36 2.3.5. Adiabatic Shear Bands . 37

2.4. Shock Waves 39 2.4.1. Hydrodynamic Treatment 39 2.4.2. More Advanced Treatments and Computer Codes 47 2.4.3. Attenuation of Shock Waves. 50 2.4.4. Elastic Precursor Waves 58

2.5. Defect Generation 60 2.5.1. Dislocation Generation . 62 2.5.2 Point Defects. 69 2.5.3. Deformation Twinning . 70 2.5.4. Displacive/Diffusionless Transformations 72 2.5.5. Other Effects . 76

Acknowledgements 77 References 77

3. Metallurgical Effects of Shock and Pressure Waves in Metals L. E. MuRR and M.A. MEYERs. 83

3.1. Principal Features of High-strain-rate and Shock deformation in Metals . 83

3.2. Permanent Changes: Residual Microstructure-Mechanical Property Relationships 92 3.2.1. Grain Size Effects . 93 3.2.2. Shock-induced Microstructures 94 3.2.3. Shock Deformation Versus Conventional Deformation

(Cold Reduction) . 104 3.2.4. Effects of Shock Pulse Duration in Shock Loading 105 3.2.5. Effects of Point Defects, Precipitates and Other Second-

Phase Particles 106 3.3. Response of Metals to Thermomechanical Shock Treatment . 108

3.3.1. Shock-mechanical Treatment, Stress-cycling and Repeated Shock Loading 109

3.3.2. Microstructural Stability and Thermal Stabilization of Substructure . 114

3.4. Summary and Conclusions Acknowledgements References

4. High-rate straining and Mechanical Properties of Materials

117 118 118

J. HARDING. 123

4.1. Introduction 123 4.2. Testing Techniques at High Rates of Strain 124

4.2.1. Testing Techniques at Intermediate Rates of Strain 126 4.2.2. Testing Techniques at Impact Rates of Strain 130 4.2.3. Attempts to Reach Higher Strain Rates 137

CONTENTS IX

4.3. Mechanical Properties of Materials at High Rates of Strain 139 4.3.1. Theoretical Considerations . 142 4.3.2. Strain-rate Dependence of fcc Materials 143 4.3.3. Strain-rate Dependence of hcp and Orthorhombic

Materials 143 4.3.4. Strain-rate Dependence of bee Materials 146 4.3.5. Mechanical Response at Very High Strain Rates . 148 4.3.6. Effect of Changing Strain Rate (Strain Rate History) 149

4.4. Mechanical Equations of State at High Rates of Strain 152 4.5. Summary . 154

References 154

5. Basic Consideration for Commercial Processes D. B. CLELAND 159

5.1. Explosive cladding 159 5.1.1. Introduction 159 5.1.2. Cladding Sites and Facilities. 162 5.1.3. Range of Products 164 5.1.4. Bonding Parameters 165

5.2. Design of Clad Assemblies 166 5.2.1. General . 166 5.2.2. Shell Plates 167 5.2.3. Tube Plates 168 5.2.4. Metal Requirements 169 5.2.5. Extension Bars 170 5.2.6. Temperature of Metals . 170

5.3. Assembly of Clads 171 5.3.1. Metal Preparation. 171 5.3.2. Assembly 171 5.3.3. Protection of Cladding Plate Surface 174

5.4. Explosives . 175 5.4.1. Main Charge . 175 5.4.2. Initiation 176

5.5. Double Sided Clads . 177 5.6. Multilayer Clads 177 5.7. Post Cladding Operations . 178

5.7.1. Preliminary Examinations 178 5.7.2. Stress Relief 178 5.7.3. Levelling 178 5.7.4. Cutting and Trimming 180 5. 7.5. Ultrasonic Testing. 180

5.8. Destructive Testing 181 5.9. Tubular Components. 184

5.9.1. Nozzles . 184 5.9.2. Other Tubular Components . 186

5.10. Explosive Hardening . 187

X CONTENTS

6. Mechanics of Explosive Welding H. EL-SOBKY 189

189 190 195 197 200 206 206 206 210 210 211 213 216

6.1. Introduction 6.2. The Mechanism of Explosive Welding 6.3. Parameters of the Explosive Welding Process

6.3.1. The Collision Parameters VP, ~, fJ 6.3.2. Limiting Conditions for Welding

6.4. Interfacial Waves 6.4.1. Introduction . 6.4.2. Mechanisms of Wave Formation

6.5. Analysis of Flow in the Collision Region . 6.5.1. Introduction . 6.5.2. The Interfacial Pressure Profile 6.5.3. The Flow Pattern in the Collision Region

References .

7. Explosive Welding in Planar Geometries M. D. CHADWICK and P. W. 1 ACKSON 219

7.1. Introduction 219 7.2. Material Combinations and Flyer Thicknesses . 220 7.3. Basic Welding Geometries 224

7.3.1. Parallel Geometries 224 7.3.2. Inclined Geometries 227 7.3.3. Parallel/Inclined Geometries . 230 7.3.4. Double Inclined Geometries . 231 7.3.5. Geometries Producing Welding Conditions

Transiently 233 7.4. Selection of Bonding Parameters 234

7.4.1. General Considerations. 234 7.4.2. Impact Velocity 236 7.4.3. Explosive Loading 240 7.4.4. Collision Angle/Collision Point Velocity 242 7.4.5. Stand-Off Distance 246 7.4.6. Anvil 248 7.4.7. Surface Finish 249

7.5. Direct Measurement of Bonding Parameters 251 7.5.1. Introduction . 251 7.5.2. The Dautriche Method . 251 7.5.3. Wire and Pin Contactor Methods 252 7.5.4. High Speed Photography 253 7.5.5. Flash Radiography 254 7.5.6. Velocity Probe 254 7.5.7. Slanting Wire Methods 255

7.6. Miscellaneous Welding Geometries for Sheets and Plates. 257 7.6.1. Lap Welding of Narrow Plates 258

CONTENTS XI

7.6.2. Seam/Line Welding of Sheets 258 7.6.3. Scarf Welding 262 7.6.4. Butt Welding. 262 7.6.5. Spot Welding. 264 7.6.6. Patch Welding 265 7.6.7. Channel Welding 265

7.7. Welding of Foils 265 7.7.1. Theoretical Considerations 265 7.7.2. Welding of Single Foils and Simple Multi-Foil

Laminates 267 7. 7.3. Wire-Reinforced Composites. 268

7.8. Applications 273 7.8.1. Introduction . 273 7.8.2. Clad Plate 274 7.8.3. Dissimilar Metal Joints. 276 7.8.4. Transition Jo;nts 277 7.8.5. Honeycomb 279

7.9. Conclusions 280 Acknowledgements 281 References . 281

8. Welding of Tubular, Rod and Special Assemblies T. z. BLAZYNSKI. 289

8.1. Introduction 289 8.2. Explosive and Implosive Welding Systems and Bonding

Parameters 290 8.2.1. Welding Systems 290 8.2.2. Welding Mechanisms 292

8.3. Welding of Duplex and Triplex Cylinders 296 8.3.1. Development of Welding Techniques 296 8.3.2. Characteristics of the Welded Systems . 300 8.3.3. Residual Stresses 304 8.3.4. Conventional Processing 311

8.4. Tube-to-tubeplate Welding 313 8.4.1. Introduction . 313 8.4.2. Geometry and Parameters 313 8.4.3. System Characteristics 318 8.4.4. Properties of Joints 320

8.5. Explosive Plugging of Tubes in Tubeplates 321 8.5.1. Applications . 321 8.5.2. Plugging Systems . 322 8.5.3. Plugs, Materials and Testing. 324

8.6. Multilayer Foil Reinforced Cylinders 326 8.6.1. Introduction . 326 8.6.2. Implosive Welding System 327 8.6.3. Pressures and Stresses 328

xii CONTENTS

8.6.4. Structural Properties 8.7. Interface Wire Mesh Reinforcement

8.7.1. Welding Systems . 8. 7.2. Metallurgical Characteristics . 8. 7.3. Mechanical Properties .

8.8. Transition Joints 8.8.1. Applications and Systems 8.8.2. The Machined Joint 8.8.3. Welding of Tubular Joints

8.9. Solid and Hollow Axisymmetric Components 8.9.1. Introduction . 8.9.2. Welding Systems . 8.9.3. Hydrostatic Extrusion

References

329 331 331 331 335 338 338 339 340 341 341 341 343 343

9. Explosive Forming J. W. ScHROEDER

9.1. Introduction 9.2. Formability of Engineering Alloys 9.3. Mechanical Properties of Explosively formed Components 9.4. Air and Underwater Forming Systems 9.5. Die and Dieless Forming . 9.6. Analysis of Final Shapes in Free-Forming 9.7. Parameters and Analysis of Die Design . 9.8. Forming of Domes and of Elements of Spherical Vessels. 9.9. Forming and Punching of Tubular Components 9.10. Miscellaneous Forming Operations 9.11. Conclusion. References .

10. Powder Compaction R. PROMMER

347

347 348 349 350 351 355 357 360 362 365 367 367

369

10.1 Introduction 369 10.2 Dynamic Compressibility of Powders 371 10.3. Type of Shock Wave and Density Distribution 373 10.4. Temperature and Strain Rate Effects. 378 1 0.5. Phase Transitions in Shock Loading Mixtures . 381 10.6. General Mechanical Properties of Compacted Powders 385 10.7. X-ray and Other Methods of Evaluating Residual Stress

Distribution 388 10.8. Basic Problems in Fabricating Semi-finished Parts . 389 10.9. Static and Dynamic Compaction: A Comparison of Material

Properties 390 References 392 Index 397

LIST OF CONTRIBUTORS

T. z. BLAZYNSKI

Department of Mechanical Engineering, University of Leeds, Leeds

LS2 9JT, UK.

M. D. CHADWICK

International Research and Development Co. Ltd, Fossway, New­

castle upon Tyne N E6 2YD, UK.

D. B. CLELAND

Metal Cladding Department, Nobel's Explosives Co. Ltd, Nobel

House, Stevenston, Ayrshire KA20 3NL, UK.

H. EL-SOBKY

Department of Mechanical Engineering, University of Manchester

Institute of Science and Technology, Sackville Street, Manchester

M60 IQD, UK.

J. HARDING

Department of Engineering Science, University of Oxford, Parks Road,

Oxford OXI 3PJ, UK.

P. w. JACKSON

International Research and Development Co. Ltd, Fossway, Newcastle

upon Tyne NE6 2YD, UK.

M.A. MEYERS

Department of Metallurgical and Materials Engineering, New Mexico

Institute of Mining and Technology, Socorro, New Mexico 8780 I, USA.

xiii

xiv LIST OF CONTRIBUTORS

L. E. MuRR

Oregon Graduate Center, 19600 NW Walker Road, Beaverton, Oregon 97006, USA.

JOHN PEARSON

Michelson Laboratories, Naval Weapons Center, China Lake, California 93555, USA.

R. PRUMMER

Fraunhofer-Institut fur Werkstoffmechanik, Rosastrasse 9, D-7800 Freiburg, Federal Republic of Germany.

J. W. ScHROEDER

Foster Wheeler Development Corporation, John Blizard Research Center, 12 Peach Tree Hill, Livingstone, New Jersey 07039, USA.