INTRODUCTION TO ENGINEERING MATERIALS

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INTRODUCTION TO ENGINEERING MATERIALS

V. B. JOHN M.Sc., C. Eng., M.I.M., M.I.M.M.

Senior Lecturer in Materials School of Engineering and Science The Polytechnic of Central London

Second Edition

M MACMILLAN

© V. B. John 1972, 1983

All rights reserved. No reproduction, copy or transmission of this publication may be made without written permission.

No paragraph of this publication may be reproduced, copied or transmitted save with written permission or in accordance with the provisions of the Copyright Act 1956 (as amended).

Any person who does any unauthorised act in relation to this publication may be liable to criminal prosecution and civil claims for damages.

First edition 1972 Reprinted 1973, 1974, 1977, 1978, 1979, 1981, 1982 Second edition 1983 Reprinted 1985

Published by Higher and Further Education Division MACMILLAN PUBLISHERS LTD Houndmills, Basingstoke, Hampshire RG21 2XS and London Companies and representatives throughout the world

ISBN 978-0-333-35911-2 ISBN 978-1-349-17190-3 (eBook) DOI 10.1007/978-1-349-17190-3

Contents Preface to the first edition Preface to the second edition Symbols used in text Units

Section A: Materials science

ix X

xi xii

1 Atomic structure 3 1.1 Introduction; 1.2 Elementary particles; 1.3 Atomic number and atomic weight; 1.4 The gramme atom and Avogadro's number; 1.5 The structure of the atom; 1.6 Quantum numbers; 1.7 The Pauli exclusion principle; 1.8 The periodic table; 1.9 The nucleus and radio-activity; 1.10 Artificial radioactive materials; 1.11 Mass defect and nuclear energy; Questions

2 Bonding between atoms 20 2.1 Introduction; 2.2 Ionic bond; 2.3 Covalent bond; 2.4 The co-ordinate bond; 2 .5 The metallic bond; 2.6 Secondary bonds; Questions

3 Chemical reactions and reactivity 29 3.1 Introduction; 3.2 Reactivity; 3.3 The Law of Mass Action; 3.4 Energy change in a reaction; 3.5 Reaction equations; 3.6 Calorific value; 3 .7 Air-fuel ratio; 3 .8 Combustion problems; 3.9 Metal extrac-tion and refining; 3 .1 0 Polymerisation; 3.11 Ionisation and pH value; 3.12 Water softening; 3.13 Electrolysis; 3.14 Corrosion; Questions

4 The crystalline state 54 4.1 Introduction; 4.2 Crystal classes; 4.3 Miller notation; 4.4 Metallic crystals; 4.5 Crystals of compounds; 4.6 Glasses; 4.7 Crystallites in polymers; 4.8 Analysis of crystals; Questions

5 Elastic and plastic behaviour 73 5.1 Stress and strain; 5.2 Elastic constants; 5.3 Thermal stresses; 5.4 Plastic flow in metals; 5.5 Slip planes; 5.6 Deformation by twin-ning; 5.7 Dislocations; 5.8 Poly crystalline metals; 5.9 Plastic deforma-tion and strain hardening; 5.10 Recrystallisation; 5.11 Solution hardening; 5.12 Dispersion hardening; 5.13 Yield point in mild steel; 5 .14 Diffusion and dislocation climb; 5.15 Behaviour of ceramic materials; 5.16 Glasses; 5.17 Polymeric materials; Questions

v

vi CONTENTS

6 Constitution 101 6.1 Phases; 6.2 Metallic alloy systems; 6.3 Total solid insolubility; 6.4 Interpretation of phase diagrams; 6.5 Solid solubility; 6.6 Phase diagram for total solid solubility; 6.7 Partial solid solubility; 6.8 Peri-tectic diagram; 6.9 Intermetallic compounds; 6.10 Effect of alloy type on properties; 6.11 Allotropy;6.12 Polymeric materials; 6.13 Ceramics; 6.14 Silicate structures; Questions

7 Electrical and magnetic properties 122 7.1 Conduction; 7.2 Band structure; 7.3 Conduction in metals; 7.4 Semiconductors; 7.5 The p-n junction; 7.6 Insulating materials, 7.7 Magnetic behaviour; Questions; Further reading

Section B: Materials technology

8 The shaping of materials 13 7 8.1 Introduction; 8.2 Melting furnaces; 8.3 Melting and alloying; 8.4 Melt treatment; 8.5 Casting; 8.6 Sand casting; 8.7 Die casting; 8.8 Other casting processes; 8.9 Ingot casting; 8.10 Hot working; 8.11 Fibre structure; 8.12 Cold working; 8.13 Annealing; 8.14 Powder metallurgy; 8.15 The forming of thermoplastics; 8.16 The forming of thermosetting plastics; 8.17 Expanded plastics; 8.18 The forming of ceramics; Questions

9 Non-ferrous metals 178 9.1 Introduction; 9.2 Aluminium; 9.3 Aluminium alloys; 9.4 Copper; 9.5 Copper alloys; 9.6 Lead; 9.7 Tin; 9.8 Magnesium; 9.9 Nickel; 9.10 Titanium; 9 .11 Zinc; Questions

10 Iron and steel 202 10.1 Introduction; 10.2 Production of iron; 10.3 Steel production; 10.4 Constituents in steel; 10.5 The iron-carbon phase diagram; 10.6 Structures of plain carbon steel; 10.7 T -T -T diagrams; 10.8 Hard­enability; 10.9 Tempering; 10.10 Heat treatments for steels; 10.11 Types of steels and their uses; 10.12 Surface hardening; 10.13 The effects of alloying elements in steels; 10.14 Alloy steels; 10.15 Cast irons; 10.16 Malleable irons; 10.17 Alloy cast irons; Questions

11 Thermoplastics 231 11.1 Introduction; 11.2 Polyethylene- PE; 11.3 Polypropylene- PP; 11 .4 Poly olefin copolymers; 11.5 Polyvinyl chloride - PVC; 11.6 Poly­tetrafluoroethylene ~- PTFE; 11.7 Polystyrene - PS; 11.8 Acrylic materials; 11.9 Polyamides (nylons) - P A; 11.10 Saturated polyesters; 11.11 Polycarbonate - PC; 11.12 Polyacetal; 11.13 Cellulosics; 11.14 Polyphenylenes; 11.15 Polysulphones; 11.16 Elastomers; 11.1 7 Silicones

12 Thermosetting materials 250 12.1 Introduction; 12.2 Phenolic materials; 12.3 Amino-formaldehyde

CONTENTS

materials; 12.4 Polyester materials; 12.5 Epoxide materials; 12.6 Poly­imides; 12.7 Polyurethanes; Questions on Chapters 11 and 12

vii

13 Ceramics 25 8 13.1 Introduction; 13.2 Building stone; 13.3 Clay products; 13.4 Re­fractories; 13.5 Cement and concrete; 13.6 Newer industrial ceramics; 13.7 Aluminium oxide; 13.8 Silicon nitride; 13.9 Glass ceramics

14 Composite materials 266 14.1 Introduction; 14.2 Timber and plywood; 14.3 Fibre reinforced materials; 14.4 Dispersion-strengthened metals; 14.5 Cermets and 'hard metal'; 14.6 Sandwich structures; Questions

15 The behaviour of materials in service 273 15 .1 Fracture; 15.2 Temperature effects and the ductile-brittle transition; 15.3 Fatigue; 15.4 Creep; 15.5 Oxidation and degradation; 15.6 Corrosion; 15.7 Corrosion protection; 15.8 Attack on polymeric materials; 15.9 Radiation damage; 15.10 Machineability; Questions

16 Testing of materials 300 16.1 Introduction; 16.2 Tensile testing machines; 16.3 Measurement of strain; 16.4 The tensile test- metals; 16.5 The tensile test -plastics; 16.6 The compression test; 16.7 Modulus of rupture; 16.8 Torsion testing; 16.9 Notchimpacttesting; 16.10Hardnesstests; 16.11 Fatigue testing; 16.12 Creep testing; 16.13 Non-destructive testing; 16.14 Vibra-tion testing; Questions; Further reading

17 Metal-joining processes 3 21 17.1 Introduction; 17.2 Soldering and brazing; 17.3 Fusion welding; 17.4 Other fusion-welding processes; 17.5 Pressure welding; 17.6 Metallurgical considerations for welding; 17.7 Defects in welds; Questions

Appendixes

Appendix A Macroscopical and microscopical examination of metals 345 A.l Macro-examination; A.2 Micro-examination; A.3 The electron microscope

Appendix B Data tables 350 Table Bl Physical properties of some pure metals Table B2 Comparison of properties of metals, plastics and ceramics

Appendix C Cost data Table Cl Some raw-material costs Table C2 Cost build-up (steel products) Table C3 Cost build-up (aluminium products) Table C4 Cost build-up (plastics industry)

352

viii CONTENTS

Appendix D A note on materials selection 3 55

Appendix E Fracture mechanics 359 E.l Introduction; E.2 Griffith's crack relationship; E.3 Stress distribu-tion at a crack tip; E.4 Applications of K1c; E.5 Yielding fracture mechanics; E.6 Determination offracture toughness; E.7 Conclusions; Further reading

Index 370

Preface to the First Edition

Not many years ago it was possible to obtain a first degree or other qualification in engineering with no knowledge whatsoever of metallurgy or the other materials of engineering. Today it is fully accepted that a sound knowledge of the science and technology of materials is very necessary to the engineer if he is to be able efficiently to translate a design into functional 'hard-ware'. The selection of materials and manufacturing route is an integral part of design procedure. Because of this, materials' science and technology now feature prominently in the educa­tional programme for all engineering technologists and technicians. Engineering, including materials' science, is also beginning to appear in the curricula of some schools.

This book was conceived against the general background of the changing patterns in engineering education, and the aim was to produce a text which dealt with the basic principles of materials science and technology in a simple, yet meaningful manner.

It is my belief that no aspect of engineering should be studied in a vacuum, but that academic studies be related to our real cost-conscious world. It is for this reason that I have included some materials' costs and a short note on the selection of materials. Although actual costs will vary from year to year, this section should be of value as it indicates the principle that any work or processing performed on a material is reflected in an increase in the cost of the material.

I wish to acknowledge the help and advice received from various individuals and organisations, and in particular to thank Professor Bob Fergusson for pro­viding the initial stimulus for this work. I am indebted to some of my colleagues at P.C.L., especially Mr C. J. Beesley, Mr G. E. Drabble, and Mr M.D. Munro Mackenzie, for their assistance in reading the manuscript and suggesting improve­ments. I also wish to acknowledge the assistance, in the way of photographs and information, which I received from the following firms and organisations: British Aluminium Company Ltd, British Metals Sinterings Association, Bound Brook Ltd, Copper Development Association, I.C.I. Ltd (Plastics Division), International Nickel Ltd, Raleigh Industries Ltd, Sintered Products Ltd, and the Zinc Develop­ment Association. Several colleges and polytechnics provided me with question papers, and I wish to record my appreciation of their help. Finally, I am very grateful to my wife for not merely putting up with me while I was struggling with the manuscript, but for helping considerably by sustaining me with refreshment and also typing some of the manuscript.

V. B. John (1972)

Preface to the Second Edition

Ten years have elapsed since this book was first published and after such a period of time an updating is necessary for any technical text. In the preparation of this edition I have attempted to satisfy two objectives; firstly to keep a basic and straightforward approach so that the text can be readily understood by students beginning their studies, and secondly to broaden the scope of the volume and so increase its suitability for degree and diploma students of both mechanical and production engineering in the later years of their courses.

When preparing a new edition of a book an author is tom between the desire to tear everything up and start again with a ream of blank paper or merely to make small cosmetic changes. This book was generally well received when it was first published and students appeared "to like the general style and content. I have, therefore, retained much of the original text and confmed myself to meeting most of the criticisms (fortunately, these were not too numerous) levelled at the first edition and also to making changes that reflect the development in my own teaching at PCL.

Some of the major differences between this text and the first edition are: (1) the inclusion of more worked examples within the text, (2) an increase in the sections dealing with dislocations and plastic deformation within metals, (3) a substantial enlargement of the chapter on material-forming processes, (4) a major increase in the chapters devoted to plastics materials, (5) a more detailed treatment of oxidation and corrosion and (6) the development of a small section on welding, formerly placed as an Appendix, into a full chapter within the book. In addition to these changes, an introduction to the principles of fracture mechanics has been included as an Appendix to the main text. It is my hope that these changes will find favour with both students and teachers.

I wish to thank my colleagues in the Materials section at PCL for the helpful comments freely given during the preparation of this revision and to record my indebtedness to my wife for her great help and for the typing of the draft.

Vernon John 1983

X

Symbols Used in Text

Quantity Symbol

Atomic mass number (atomic weight) M Atomic number z Avogadro's number No N 0 = 6.023 X 1023

molecules per mole Bulk modulus of elasticity K Direct strain € Direct stress u Force F Glass transition temperature Tg Modulus of rigidity G Poisson's ratio " (Greek nu) Shear strain 'Y Shear stress T Temperature T Time t Universal constant Ro R 0 = 8.314 kJ/kmol K Young's modulus of elasticity E

xi

Units

The units used throughout this book conform to the SI system. The principal units that are quoted in the text are given below. Preferred SI units are printed in bold type.

Quantity

mass

length

time

temperature

amount of substance

area

volume

density

force

stress (pressure)

energy

Unit

kllogramme gramme tonne

metre millimetre second minute hour degree Kelvin degree Celsius mole kllomole square metre square millimetre cubic metre cubic millimetre kllogramme per cubic metre

newton kilonewton meganewton newton per square metre

meganewton per square metre giganewton per square metre pascal bar joule

xii

Symbol

kg (1 kg= 2.205 lb) g t (Mg)(l t = 1000 kg

= 0.984 ton) m (1m= 39.37 in) mm s min h K oc mol kmol m2 mm2

m3 (1m3 = 35.315 ft3 )

mm3

kg/m3 (1 kg/m3

= 10-3 g/cm3

= 0.062lb/ft3 )

N (1 N = 0.225 lbf) kN MN N/m2 (1 N/m2

= 0.000145lbf/in2 )

MN/m2 (I MN/m2

= 0.0648 tonf/in2 )

GN/m2

Pa (I Pa = 1 N/m2 )

bar orb (1 bar= 105 N/m2 ) J (Nm)

UNITS xiii

Quantity Unit Symbol

calorific value (mass) megajoule per kilogramme MJ/kg (1 MJ/kg = 429.5 Btu/lb)

calorific value (volume) megajoule per cubic metre MJ/m3 (1 MJ/m3

= 26.81 Btu/ft3 ) electric current ampere A voltage volt v quantity of electricity coulomb C(As) electrical resistance ohm n (V/A) electrical resistivity ohm metre nm magnetic flux weber Wb (V s) magnetic flux density tesla T (Wb/m2 )

(1 T = 104 gauss) frequency hertz Hz (s-1)