Materials for Engineers and Technicians
W. Bolton, R.A. Higgins
- 472 pages
- English
- ePUB (mobile friendly)
- Available on iOS & Android
Materials for Engineers and Technicians
W. Bolton, R.A. Higgins
About This Book
A comprehensive yet accessible introduction to materials engineering which provides a straightforward, readable approach to the subject. The sixth edition includes a new chapter on the selection of materials, an updated discussion of new materials, and a complete glossary of key terms used in materials engineering.
This renowned text has provided many thousands of students with an easily accessible introduction to the wide ranging subject area of materials engineering and manufacturing processes for over forty years. It avoids the excessive jargon and mathematical complexity so often found in textbooks for this subject, retaining the practical down-to-earth approach for which the book is noted. The increased emphasis on the selection of materials reflects the increased emphasis on this aspect of materials engineering now seen within current vocational and university courses.
In addition to meeting the requirements of vocational and undergraduate engineering syllabuses, this text will also provide a valuable desktop reference for professional engineers working in product design who require a quick source of information on materials and manufacturing processes.
Frequently asked questions
Information
1 Engineering materials
1.1 Introduction
1.2 The requirements
- The conditions under which the product is to be used, i.e. the service requirements. These dictate the properties required of a material. For example, if a product is to be subject to forces then it might need strength and toughness and/or if subject to a corrosive environment it might require corrosive resistance.
- The methods proposed for the manufacture of the product. For example, if a material has to be bent as part of its processing then it must be ductile enough to be bent without breaking. A brittle material could not be used.
- The price of the material and its availability and the cost of making the product.
1.2.1 Properties of materials
- Mechanical properties: these include such properties as density, and the properties displayed when a force is applied to a material, e.g. yield strength, strength, stiffness, hardness, toughness, fatigue strength (how many times can it be flexed back-and-forth before it breaks?), creep strength (how will it change in length with time when subject to a constant force?).
- Electrical properties: these are the properties displayed when the material is used in electrical circuits or electrical components and include resistivity, conductivity and resistance to electrical breakdown.
- Magnetic properties: these are relevant when the material is used as, for example, a magnet or part of an electrical component such as an inductor which relies on such properties.
- Thermal properties: these are the properties displayed when there is a heat input to a material and include expansivity and heat capacity.
- Optical properties: these include transparency.
- Surface properties: these are, for example, relevant in con siderations of abrasion and wear, corrosion and solvent resistance.
- Aesthetic properties: these include appearance, texture and the feel of a material.
1.3 The materials
- The Stone Age (about 10000 BC-3000 BC). People could only use the materials they found around them such as stone, wood, clay, animal hides, bone, etc. The products they made were limited to what they could fashion out of these materials, thus they had tools made from stone, flint, bone and horn, with weapons - always at the forefront of technology at any time - of wood and flint.
- The Bronze Age (3000 BC-1000 BC). By about 3000 bc, people were able to extract copper from its ore. Copper is a ductile material which can be hammered into shapes, thus enabling a greater variety of items to be fashioned than was possible with stone. The copper ores contained impurities that were not completely removed by the smelting and so copper alloys were produced. It was found that when tin was added to copper, an alloy, bronze, was produced that had an attractive colour, was easy to form and harder than copper alone.
- The Iron Age (1000 BC-1620 AD). About 1000 BC the extraction of iron from its ores signalled another major development. Iron in its pure form was, however, inferior to bronze but by heating items fashioned from iron in charcoal and hammering them, a tougher material, called steel, was produced. Plunging the hot metal into cold water, i.e. quenching, was found to improve the hardness. Then reheating and cooling the metal slowly produced a less hard but tougher and less brittle material, this process now being termed tempering. Thus heat-treatment processes were developed.
- The Cast Iron Age (1620 AD-1850 AD). Large-scale iron production with the first coke-fuelled blast-furnace started in 1709. The use of cast iron for structures and machine parts grew rapidly after 1750, including its use for casting cannon. In 1777, the first cast iron bridge was built over the River Severn near Coalbrookdale. Cast iron established the dominance of metals in engineering. The term Industrial Revolution is used for the period that followed as the pace of developments of materials and machines increased rapidly and resulted in major changes in the industrial environment and the products generally available. During this period, England led the world in the production of iron.
- The Steel Age (1860 AD onwards). Steel was a special-purpose material during the first half of the nineteenth century. However, the year 1860 saw the development of the Bessemer and open hearth processes for the production of steel, and this date may be considered to mark the general use of steel as a constructional material. This development reinforced the dominance of metals in engineering.
- The Light Alloys Age (such alloys only widely used from 1940 onwards). Although aluminium was first produced, in minute quantities, by H. C. Oersted in 1825, it was not until 1886 that it was produced commercially. The high strength aluminium alloy duralumin was developed in 1909, high strength mckel-chromium alloys for high temperature use m 1931, Titanium was first produced commercially in 1948.
- The Plastics Age (1930 onwards). The first manufactured plastic, celluloid, was developed in 1862; in 1906, Bakelite was developed. The period after about 1930 saw a major development of plastics and their use in a wide range of products. In 1933, a Dutch scientist, A. Michels, was carrying out research into the effects of high pressure on chemical reactions when he obtained a surprise result - the chemical reaction between ethylene and benzaldehyde was being studied at a pressure of 2000 times the atmospheric pressure and a temperature of 170°C when a waxy solid was found to form. This is the material we call polyethylene. The commercial production of polyethylene started in England in 1941. The development of polyvinyl chloride was, unlike the accidental discovery of polythene, an investigation where a new material was sought. In 1936, there was no readily available material that could replace natural rubber and since, in the event of a war Britain's natural rubber supply from the Far East would be at risk, a substitute was required. In July 1940, a small amount of PVC was produced with commercial production of PVC starting in 1945.
- The Composites Age (from about 1950s onwards). Though composites are not new, bricks and concrete being very old examples, it is only in the second half of the twentieth century that synthetic composites became widely used. Reinforced plastics are now very widely used and carbon-fibre reinforced composites are, from their initial development in the 1960s, now becoming widely enough used to become known to the general public.
1.3.1 Materials classification
- Metals: these are based on metallic chemical elements...