Metals

9 Key excerpts on "Metals"

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  eBook - PDF

  Fundamentals of Modern Manufacturing

  Materials, Processes, and Systems

  • Mikell P. Groover(Author)
  • 2019(Publication Date)
  • Wiley

    (Publisher)

  93 ENGINEERING MATERIALS P A R T II 6 Part II covers the four types of engineering materials: (1) met- als, (2) ceramics, (3) polymers, and (4) composites. Metals are the most important engineering materials and the topic of this chapter. A metal is a category of materials generally characterized by properties of ductility, malleability, luster, and high electrical and thermal conductivity. The category includes both metallic elements and their alloys. Metals have properties that satisfy a wide variety of design require- ments. The manufacturing processes by which they are shaped into products have been developed and refined over many years; indeed, some of the processes date from ancient times (see Historical Note 1.2). In addition, the properties of Metals can be enhanced through heat treatment, covered in Chapter 26. The technological and commercial importance of Metals derives from the following general properties possessed by vir- tually all of the common Metals: • High stiffness and strength. Metals can be alloyed for high strength, and hardness; thus, they are used to provide the structural framework for most engineered products. • Toughness. Metals have the capacity to absorb energy better than other classes of materials. • Good electrical conductivity. Metals are conductors because of their metallic bonding that per- mits the free movement of electrons as charge carriers. • Good thermal conductivity. Metallic bonding also explains why Metals generally conduct heat better than ceramics or polymers. In addition, certain Metals have specific properties that make them attractive for specialized applica- tions. Many common Metals are available at relatively low cost per unit weight and are often the material of choice simply because of their low cost. Metals are converted into parts and products using a variety of manufacturing processes. The starting form of the metal differs, depending on the process.

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  Fundamentals of Modern Manufacturing

  Materials, Processes, and Systems

  • Mikell P. Groover(Author)
  • 2016(Publication Date)
  • Wiley

    (Publisher)

  94 P A R T 6 6.1 Alloys and Phase Diagrams 6.1.1 Alloys 6.1.2 Phase Diagrams 6.2 Ferrous Metals 6.2.1 The Iron–Carbon Phase Diagram 6.2.2 Iron and Steel Production 6.2.3 Steels 6.2.4 Cast Irons 6.3 Nonferrous Metals 6.3.1 Aluminum and Its Alloys 6.3.2 Magnesium and Its Alloys 6.3.3 Copper and Its Alloys 6.3.4 Nickel and Its Alloys 6.3.5 Titanium and Its Alloys 6.3.6 Zinc and Its Alloys 6.3.7 Lead and Tin 6.3.8 Refractory Metals 6.3.9 Precious Metals 6.4 Superalloys Part II covers the four types of engineering materials: (1) Metals, (2) ceramics, (3) polymers, and (4) composites. Metals are the most important engineering materials and the topic of this chap- ter. A metal is a category of materials generally characterized by properties of ductility, malleability, luster, and high electrical and thermal conductivity. The category includes both metallic elements and their alloys. Metals have properties that satisfy a wide variety of design requirements. The manufacturing pro- cesses by which they are shaped into products have been devel- oped and refined over many years; indeed, some of the processes date from ancient times (see Historical Note 1.2 at www.wiley .com/college/groover). In addition, the properties of Metals can be enhanced through heat treatment, covered in Chapter 26. The technological and commercial importance of Metals derives from the following general properties possessed by vir- tually all of the common Metals: • High stiffness and strength. Metals can be alloyed for high strength, and hardness; thus, they are used to provide the structural framework for most engineered products. • Toughness. Metals have the capacity to absorb energy better than other classes of materials. Metals II ENGINEERING MATERIALS • Good electrical conductivity. Metals are conductors because of their metallic bonding that per- mits the free movement of electrons as charge carriers.

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  Parts Fabrication

  Principles and Process

  • Richard Crowson(Author)
  • 2006(Publication Date)
  • CRC Press

    (Publisher)

  27 Materials Characteristics of Metals Jack M. Walker 2.0 INTRODUCTION TO MATERIALS CHARACTERISTICS OF Metals Modern industry is dependent on a knowledge of metallurgy. Nearly every kind of manufacturing today is affected by the behavior of Metals and alloys. Therefore, anyone who plans a career in modern industry will find a working knowledge of metallurgical processing to be a valuable asset. Today’s manufacturing engineer may not need to be a materials engineer or met-allurgist, in addition to all the other skills that he or she uses in the broader role that we have discussed in several chapters of this handbook. However, to understand the forming, chip cutting, and processing principles involved in fabricating parts of metal, and in order to participate in a product design team, introductory background information is essential. Some of us are quite familiar with the terms and properties of many of the common Metals, while others are specialists in different fields and need an overview of the subject. The approach the author has taken in this chapter is to introduce the materials most commonly used, and provide an explanation of the properties that make a particular material or alloy a desirable choice for a specific application. It will make a difference in the machines selected, the design of the tooling, and the cost of the part fabrication and finishing. Different materials require different heat treatments and different surface finishes. Subchapter 2.1 discusses metallurgy, 2.2 introduces iron and steel (ferrous Metals), 2.3 talks about aluminum and other non-ferrous materials, and 2.4 describes the peculiarities of magnesium. 2.1 FUNDAMENTALS OF METALLURGY Metallurgy is the art and science concerned with Metals and their alloys.

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  Electronic Materials

  Principles and Applied Science

  • Yuriy Poplavko(Author)
  • 2018(Publication Date)
  • Elsevier

    (Publisher)

  liquid conductors are also of technical interest: they are various electrolytes and molten Metals. However, for most Metals, rather high melting point is peculiar; only mercury and some special alloys (e.g., indium-gallium alloy) can be applied as liquid conductors at conventional temperatures.

  The mechanism of current flowing in Metals—as in both solid and liquid phases—is due to the movement of electrons; therefore, they are called as conductors with electronic conductivity .

  5.1 Defining Features of Metals

  The term “metal” originated from the Greek word “metallon,” which means “mine.” Distinctive properties of Metals are high electrical conductivity, ability to reflect light (shine), mechanical plasticity and flexibility, as well as large thermal conductivity.

  Most chemical elements (simple substances) are Metals, and many alloys of these elements and their compounds are also Metals. Sometimes, other substances can be referred to as Metals, having one or other of metallic properties, and they are called “synthetic Metals” (intercalated), “organic Metals,” and others. Of 119 elements of Mendeleev's periodic table, 92 are Metals. The boundary between Metals and nonMetals in this periodic table has a diagonal from B to At. Some elements, such as germanium (Ge) and antimony (Sb), are difficult to be qualified; however, Ge is considered as a semiconductor, while Sb is a semimetal. It is interesting to note that tin can exist in metallic modification (β-Sn), so in a semiconducting phase (α-Sn).

  However, in Ge, Si, P, and some other “nonMetals” another modifications can be obtained under increased pressure that exhibit properties of Metals. Moreover, at super high pressure all substances must acquire properties of Metals [1] . To find out whether any material is metal or nonmetal, not only physical properties but also chemical properties should be taken into account. Sometimes, for elements that lie on the border between Metals and nonMetals the term semimetal

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  Automotive Handbook

  • (Author)
  • 2022(Publication Date)
  • Wiley

    (Publisher)

  Materials 271 Metallic materials The Metals generally have a crystalline structure. Their atoms are arranged in a regular crystal lattice. The valence elec- trons of the atoms are not bound to a specific atom, but are able to move freely within the metal lattice – a metallic bond is present. This special metal-lattice struc- ture explains the characteristic properties of Metals: the ductility and resulting high level of formability, the high electric con- ductivity, the high level of thermal con- ductivity, the low light transmission and the great optical reflective ability (metallic gloss). The metallic materials used most often in technical applications include ferrous material. Iron base alloys are primarily used for this. An alloy is defined as a me- tallic material that consists of at least two chemical elements. The ferrous materials are divided into groups for steels and cast iron materi- als. The main difference between the two groups is carbon content. The carbon con- tent of steel is generally less than 2 % and over 2 % for cast iron (for details, see EN metallurgy standards). Steels Structural compositions of steels Structural compositions of steels The majority of steels primarily consists of iron and other property-determining alloying elements such as chrome, nickel, vanadium, molybdenum and titanium. The most important alloying element is carbon, which is diffused in the iron lat- tice and present as iron carbide (Fe 3 C), also called cementite. Various phases are present in the steel with their character- istic properties depending on the carbon content, the alloying elements and heat treatment (e. g. hardening, quenching and drawing). They can be found in the iron / carbon diagram (Figure 1). The most im- portant phases are described below. Ferrite The ferritic structure exhibits a body- centered cubic atomic arrangement. It is soft, easily formable and ferromagnetic (e. g. S235).

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  Materials NQF3 SB

  TVET FIRST

  • Sparrow Consulting(Author)
  • 2013(Publication Date)
  • Macmillan

    (Publisher)

  (c) Reflecting light. (d) Conduct an electric current. (e) Stretched (drawn out) into a wire. (f) Silver, copper, and gold are examples of high-conductivity Metals. (g) Sheen or polished look of a metal. (h) Forming a thin sheet. (i) Thermal equilibrium. Property Description Electrical conductivity Heat conductivity Malleability Ductility Lustrous appearance 50 Module 2: Describe, select and use Metals for construction purposes Unit 2 .3: Rank Metals used in construction according to their properties Materials are often subject to forces (loads) when they are used. Therefore mechanical engineers normally calculate these forces to determine how materials will deform or break as a function of the applied load, time, temperature and other conditions. The mechanical properties of Metals, namely strength, hardness, toughness, elasticity, plasticity, brittleness, ductility and malleability are used as a measurement of how Metals behave under these loads. They are described in terms of the types of force or stress that the metal must withstand and how these are resisted. In this unit you will learn more about the properties described below and how Metals are ranked according to these properties. • Yield strength. • Melting or freezing point. • Electrical conductivity. • Coefficient of thermal expansion. • Cost. • Hardness. • Density. Yield strength Yield strength is the maximum load that can be applied to a metal before it deforms permanently. The metal will deform elastically until it reaches its yield point , from which point onwards plastic deformation will occur. Melting or freezing point The melting or freezing point of a metal is the constant temperature at which the solid and liquid phases of the metal are in equilibrium . The metal will melt (turn into a liquid) just above this temperature and freeze (turn into a solid) just below it. Electrical conductivity As discussed, electrical conductivity is the ability of a metal to conduct an electric current.

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  Manufacturing Engineering Processes, Second Edition

  • Leo Alting(Author)
  • 2020(Publication Date)
  • CRC Press

    (Publisher)

  In forming from the liquid material state, the final material properties depend mainly on the composition (including solidification temperature range), the thermal and mechanical properties of the molding or die material, and the solidification conditions (direction, rate, etc.). In forming from the solid material state by plastic deformation, the amount of deformation, the temperature, and the rate of deformation primarily determine the final properties. Cold deformation increases the strength and decreases the ductility of the material. Hot deformation gives poor surface quality and reasonably good mechanical properties. Solid-state forming by machining (mass-reducing processes) primarily influences the surface properties (roughness, hardness, internal stresses, etc.). The examples mentioned only serve to illustrate the complexity of the evaluation of the final material properties of a component. These problems are discussed in more detail in some of the later chapters.

  3.4 CLASSIFICATION OF MATERIALS

  As mentioned previously, it is very difficult to provide broad information regarding all the important engineering materials in this context. Consequently, only a general survey will be given to allow a rough evaluation of the suitability of the different material groups for various processes. From this survey and the process descriptions in the later chapters, a reasonable background for the evaluation of the final properties of the materials will be available.

  Engineering materials can be divided into groups showing important relationships. In this context the traditional classification shown in Fig. 3.1 will be followed.

  The main groups are metallic materials, nonmetallic materials, and composite materials. Composite materials are built up from two or more materials, so that new and special properties are obtained. Metallic materials are subdivided into ferrous and nonferrous Metals. The nonmetallic materials are subdivided into polymers, ceramics, and glasses, but the group covers many other materials (wood, concrete, bricks, etc.) that are not important for the present discussion.

  FIGURE 3.1 Classification of some of the engineering materials.

  3.5 METALLIC MATERIALS

  3.5.1 Bonding and Structure

  Metals are characterized by the metallic bonding , where the metal ions are held together by an “electron cloud.” This type of bonding has a high mobility of the free (valence) electrons and accounts in general for the high strength level, the ductility (ability to be deformed without fracture), and the relatively high melting temperature of Metals. These general tendencies can be influenced by many factors; consequently, exceptions are common.

  Metals have a crystalline structure with predominantly body-centered cubic, face-centered cubic, or close-packed hexagonal lattice structures. Crystalline materials normally consist of thousands of small individual crystals or grains, depending on the production method. During solidification, many individual lattices begin to form at various points within the melt. As solidification proceeds these crystals or grains, which have random orientation, grow, meet, and form the grain boundaries (Fig. 3.2

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  eBook - ePub

  Engineering Fundamentals

  • Roger Timings(Author)
  • 2007(Publication Date)
  • CRC Press

    (Publisher)

  4     Engineering materialsand heat treatment

  When you have read this chapter you should understand: •    How to define the basic properties of engineering materials. •    How to correctly identify and select a range of engineering Metals and alloys. •    How to correctly identify and select a range of non-metallic materials suitable for engineering applications. •    Safe working practices as applicable to heat treatment processes. •    The principles and purposes of heat treatment. •    The through hardening of plain carbon steels. •    The carburizing and case-hardening of low carbon steels. •    How to temper hardened steels. •    How to anneal and normalize steels. •    The basic heat treatment of non-ferrous Metals and alloys. •    The principles, advantages and limitations of heat treatment furnaces. •    The temperature control of heat treatment furnaces. •    The advantages, limitations and applications of quenching media.

  4.1   States of matter

  Almost all matter can exist in three physical states by changing its temperature in appropriate conditions. These states are solids, liquids and gases.

  •    Ice is solid water and exists below 0°C.

  •    Water is a liquid above 0°C and below 100°C.

  •    Steam is water vapour above 100°C and becomes a gas as its temperature is raised further (superheated).

  Metals such as brass, copper or steel are solid (frozen) at room temperatures but become liquid (molten) if heated to a sufficiently high temperature. If they are heated to a high enough temperature they will turn into a gas. On cooling, they will first turn back to a liquid and then back to a solid at room temperature. Providing no chemical change takes place (oxidation of the metal through contact with air at high temperatures) we can change substances backwards and forwards through the three states by heating and cooling as often as we like.

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  T Level Engineering

  Technology, Manufacture and Maintenance

  • Andrew Livesey(Author)
  • 2023(Publication Date)
  • Routledge

    (Publisher)

  Chapter 8 Engineering Materials

  DOI: 10.1201/9781003284833-8

  Engineers tend to classify materials into two major groups, each with two sub-groups. The major groups are metallic materials and non-metallic materials. We’ll look at each in turn (Table 8.1 ).

  Table 8.1

  Metallic Materials and Non-Metallic Materials

  Engineering Materials
  Metallic Materials
  Ferrous – contains iron	Non-ferrous – does not contain iron
  Iron in various forms	Aluminium
  Low-carbon steel	Brass – copper and zinc
  Medium-carbon steel	Bronze – copper and tin
  High-carbon steel	Chromium
  Alloy steel	Copper
  Titanium
  Non-Metallic Materials
  Natural – occur in nature	Synthetic – man-made materials
  Leather	Carbon fibre
  Wood	GRP – glass fibre
  Wool	Vegan leather
  Bamboo	Thermo-plastics
  Cotton cloth	Thermo-setting plastics

  Metallic Materials

  The metallic group is divided into two sub-groups, these are ferrous Metals and non-ferrous Metals. Ferrous simply means iron, all ferrous Metals contain iron. Non-ferrous Metals do not contain iron.

  Iron is dug from the ground and heated in a furnace – there are several different types of furnaces – and mixed with carbon to form steel. Steel has been used for engineering and construction since about 500 BC. When we talk about steel it is important to realise that there are several major categories of steel: low-carbon, medium-carbon, high-carbon and many types of alloy steel. When we talk about alloy steel, we simply mean that it is steel mixed with another element.

  Tech note

  Ferrous – contains iron.

  Alloy – a mixture of a metal and another element.

  Manufacture of Steel

  Iron ore which is dug up from the ground is fed into a blast furnace together with limestone and coke. The coke is used as a source of heat and the limestone as a flux, that is an agent which cleans and helps the flow of the metal. It separates the metal from the impurities in the mixture. The molten metal is then poured out of the furnace into moulds to form what are called pigs – chunks of iron which resemble the shape of a pig’s body. Because of the burning process the pig iron contains between 3–4% carbon.

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