Metallurgy 19722 225045741 2008-07-11T16:59:56Z Vsmith 84417 /* See also */ cap acronym link [[Image:Georg_Agricola.jpg|thumb|right|200px|Georg Agricola, author of ''De re metallica'', an important early book on metal extraction]] '''Metallurgy''' is a domain of [[materials science]] that studies the physical and chemical behavior of metallic [[Chemical element|elements]], their [[intermetallics|intermetallic compounds]], and their compounds, which are called [[alloy]]s. It is also the [[technology]] of metals: the way in which science is applied to their practical use. Metallurgy is commonly used in the [[craft]] of [[metalworking]]. ==History== {{main|History of ferrous metallurgy}} {{see also|Chalcolithic|Bronze Age|Iron Age|Metallurgy in pre-Columbian Mesoamerica|History of metallurgy in the Indian subcontinent}} [[Image:Yuan Dynasty - waterwheels and smelting.png|thumb|left|260px|An illustration of furnace bellows operated by [[waterwheel]]s, from the ''Nong Shu'', by Wang Zhen, 1313 AD, during the Chinese [[Yuan Dynasty]].]] The earliest recorded metal employed by humans appears to be [[gold]] which can be found free or "native". Small amounts of natural gold have been found in Spanish caves used during the late [[Paleolithic]] period, ''c.'' 40,000 BC.<ref>{{cite web | url = http://www.gold-eagle.com/gold_digest/history_gold.html | title = History of Gold | publisher = Gold Digest | accessdate = 2007-02-04 }}</ref> [[Image:GoldThebes750.jpg|thumb|right|Gold headband from Thebes 750-700 BC]] [[Silver]], [[copper]], [[tin]] and meteoric [[iron]] can also be found native, allowing a limited amount of [[metalworking]] in early cultures. Egyptian weapons made from meteoric iron in about 3000 B.C. were highly prized as "Daggers from Heaven"<ref>W. Keller (1963) ''The Bible as History'' page 156 ISBN 0 340 00312 X</ref>. However, by learning to get [[copper]] and [[tin]] by heating rocks and combining [[copper]] and [[tin]] to make an [[alloy]] called [[bronze]], the technology of metallurgy began about 3500 B.C. with the [[Bronze Age]]. The extraction of [[iron]] from its ore into a workable metal is much more difficult. It appears to have been invented by the [[Hittites]] in about 1200 B.C., beginning the [[Iron Age]]. The secret of extracting and working iron was a key factor in the success of the [[Philistines]]<ref>W. Keller (1963) ''The Bible as History'' page 177 ISBN 0 340 00312 X</ref><ref>B. W. Anderson (1975) ''The Living World of the Old Testament'' page 154 ISBN 0-582-48598-3</ref> Historical developments in ferrous metallurgy can be found in a wide variety of past cultures and civilizations. This includes the ancient and medieval kingdoms and empires of the [[Middle East]] and [[Near East]], ancient [[Egypt]] and [[Anatolia]] ([[Turkey]]), [[Carthage]], the [[Greeks]] and [[ancient Rome|Roman]]s of ancient [[Europe]], medieval Europe, ancient and medieval [[China]], ancient and medieval [[India]], ancient and medieval [[Japan]], etc. Of interest to note is that many applications, practices, and devices associated or involved in metallurgy were possibly established in ancient China before Europeans mastered these crafts (such as the innovation of the [[blast furnace]], [[cast iron]], [[steel]], [[hydraulic]]-powered [[trip hammer]]s, etc.)<ref> R. F. Tylecote (1992) A History of Metallurgy ISBN 0-901462-88-8</ref>. However, modern research suggests that [[Roman technology]] was far more sophisticated than hitherto supposed, especially in [[mining]] methods, metal extraction and [[forging]]. They were for example expert in [[hydraulic mining]] methods well before the Chinese, or any other civilization of the time{{Fact|date=April 2008}}. A 16th century book by [[Georg Agricola]] called [[De re metallica]] describes the highly developed and complex processes of mining metal ores, metal extraction and metallurgy of the time. Agricola has been described as the "father of metallurgy"<ref>[[Karl Alfred von Zittel]] (1901) ''History of Geology and Palaeontology'' page 15</ref> == Extractive metallurgy == [[Extractive metallurgy]] is the practice of removing valuable metals from an [[ore]] and refining the extracted raw metals into a purer form. In order to convert a metal [[oxide]] or [[sulfide]] to a purer metal, the ore must be [[redox|reduced]] either physically, [[chemistry|chemically]], or [[electrolyte|electrolytically]]. Extractive metallurgists are interested in three primary streams: feed, concentrate (valuable metal oxide/sulfide), and [[tailings]] (waste). After mining, large pieces of the ore feed are broken through crushing and/or grinding in order to obtain particles small enough where each particle is either mostly valuable or mostly waste. Concentrating the particles of a value in a form supporting separation enables the desired metal to be removed from waste products. Mining may not be necessary if the ore body and physical environment are conducive to [[In-situ leaching|leaching]]. Leaching dissolves minerals in an ore body and results in an enriched solution. The solution is collected and processed to extract valuable metals. Ore bodies often contain more than one valuable metal. Tailings of a previous process may be used as a feed in another process to extract a secondary product from the original ore. Additionally, a concentrate may contain more than one valuable metal. That concentrate would then be processed to separate the valuable metals into individual constituents. ==Important common alloy systems== Common engineering [[metal]]s include [[aluminium]], [[chromium]], [[copper]], [[iron]], [[magnesium]], [[nickel]], [[titanium]] and [[zinc]]. These are most often used as alloys. Much effort has been placed on understanding the iron-carbon alloy system, which includes [[steel]]s and [[cast iron]]s. Plain carbon steels are used in low cost, high strength applications where weight and [[corrosion]] are not a problem. Cast irons, including [[ductile iron]] are also part of the iron-carbon system. [[Stainless steel]] or [[galvanized steel]] are used where resistance to corrosion is important. Aluminium alloys and magnesium alloys are used for applications where strength and lightness are required. Cupro-nickel alloys such as [[Monel]] are used in highly corrosive environments and for non-magnetic applications. Nickel-based [[superalloy]]s like [[Inconel]] are used in high temperature applications such as turbochargers, pressure vessels, and heat exchangers. For extremely high temperatures, single crystal alloys are used to minimize creep. == Production engineering of metals == In [[industrial engineering|production engineering]], metallurgy is concerned with the production of metallic components for use in consumer or [[engineering]] products. This involves the production of alloys, the shaping, the heat treatment and the surface treatment of the product. The task of the metallurgist is to achieve balance between material properties such as cost, [[weight]], [[tensile strength|strength]], [[toughness]], [[Hardness (materials science)|hardness]], [[corrosion]] and [[fatigue (material)|fatigue]] resistance, and performance in [[temperature]] extremes. To achieve this goal, the operating environment must be carefully considered. In a saltwater environment, ferrous metals and some aluminium alloys corrode quickly. Metals exposed to cold or [[cryogenic]] conditions may endure a ductile to brittle transition and lose their toughness, becoming more brittle and prone to cracking. Metals under continual cyclic loading can suffer from metal fatigue. Metals under constant [[stress (physics)|stress]] at elevated temperatures can [[creep (deformation)|creep]]. ===Metal working processes=== Metals are shaped by processes such as [[casting]], [[forging]], [[Flow Forming|flow forming]], [[Rolling (metalworking)|rolling]], [[extrusion]], [[sintering]], [[metalworking]], [[machining]] and [[Fabrication (metal)|fabrication]]. With casting, molten metal is poured into a shaped [[Molding (process)|mould]]. With forging, a red-hot [[Billet (manufacturing)|billet]] is hammered into shape. With rolling, a billet is passed through successively narrower rollers to create a sheet. With extrusion, a hot and malleable metal is forced under pressure through a [[die]], which shapes it before it cools. With sintering, a [[powder metallurgy|powdered metal]] is compressed into a die at high temperature. With machining, [[Lathe (tool)|lathes]], [[milling machine]]s, and [[drill]]s cut the cold metal to shape. With fabrication, sheets of metal are cut with [[guillotine]]s or [[gas welding|gas cutters]] and bent into shape. "[[Cold work]]ing" processes, where the product’s shape is altered by rolling, fabrication or other processes while the product is cold, can increase the strength of the product by a process called [[work hardening]]. Work hardening creates [[dislocation|microscopic defects]] in the metal, which resist further changes of shape. Various forms of [[casting]] exist in industry and academia. These include [[sand casting]], [[investment casting]] (also called the “[[lost wax process]]”), [[die casting]] and [[Continuous Casting|continuous casting]]. ===Joining=== ====Welding==== {{Main|Welding}} [[Welding]] is a technique for joining metal components by melting the base material. A filler material of similar composition may also be melted into the joint. ====Brazing==== {{Main|Brazing}} [[Brazing]] is a technique for joining metals at a temperature below their melting point. A filler with a melting point below that of the base metal is used, and is drawn into the joint by capillary action. Brazing results in a mechanical and metallurgical bond between work pieces. ====Soldering==== {{Main|Soldering}} [[Soldering]] is a method of joining metals below their melting points using a filler metal. Soldering results in a mechanical joint and occurs at lower temperatures than brazing. ===Heat treatment=== {{Main|Heat treatment}} Metals can be [[heat treatment|heat treated]] to alter the properties of strength, ductility, toughness, hardness or resistance to corrosion. Common heat treatment processes include [[Annealing (metallurgy)|annealing]], [[precipitation strengthening]], [[quenching]], and [[tempering]]. The '''annealing''' process softens the metal by allowing recovery of cold work and grain growth. '''Quenching''' can be used to harden alloy steels, or in precipitation hardenable alloys, to trap dissolved solute atoms in solution. '''Tempering''' will cause the dissolved alloying elements to precipitate, or in the case of quenched steels, improve impact strength and ductile properties. ===Surface treatment=== ====Plating==== {{Main|Plating}} [[Electroplating]] is a common surface-treatment technique. It involves bonding a thin layer of another metal such as [[gold]], [[silver]], [[chromium]] or [[zinc]] to the surface of the product. It is used to reduce corrosion as well as to improve the product's aesthetic appearance. ====Thermal spray==== {{Main|Thermal spray}} Thermal spraying techniques are another popular finishing option, and often have better high temperature properties than electroplated coatings. ====Case hardening==== {{Main|Case hardening}} Case hardening is a process in which an alloying element, most commonly carbon or nitrogen, diffuses into the surface of a monolithic metal. The resulting interstitial solid solution is harder than the base material, which improves wear resistance without sacrificing toughness. == Electrical and electronic engineering == Metallurgy is also applied to electrical and electronic materials where metals such as [[aluminium]], [[copper]], [[tin]], [[silver]], and [[gold]] are used in power lines, wires, [[printed circuit board]]s and [[integrated circuit]]s. ==Metallurgical techniques== [[Image:AlubronzeCuAl20v500.png|thumb|165px|Metallography allows the metallurgist to study the microstructure of metals.]] Metallurgists study the microscopic and macroscopic properties using [[metallography]], a technique invented by [[Henry Clifton Sorby]]. In metallography, an alloy of interest is ground flat and polished to a mirror finish. The sample can then be etched to reveal the microstructure and macrostructure of the metal. A metallurgist can then examine the sample with an optical or [[electron microscope]] and learn a great deal about the sample's composition, mechanical properties, and processing history. [[Crystallography]], often using [[diffraction]] of [[x-ray]]s or [[electron]]s, is another valuable tool available to the modern metallurgist. Crystallography allow the identification of unknown materials and reveals the crystal structure of the sample. Quantitative crystallography can be used to calculate the amount of phases present as well as the degree of strain to which a sample has been subjected. The physical properties of metals can be quantified by [[mechanical testing]]. Typical tests include tensile [[Strength of materials|strength]], compressive strength, hardness, impact toughness, fatigue and creep life. ==See also== * [[Archaeometallurgy]] * [[Fabrication (metal)]] * [[Georg Agricola]] * [[Metalworking]] * [[National Institute of Foundry and Forge Technology]] * [[Pyrometallurgy]] * [[Timeline of materials technology]] * [[CALPHAD (method)]] ==References== {{reflist}} ==External links== * [[Wikiversity:Topic:Metallurgical engineering]] {{Technology}} [[Category:Metallurgy|*]] [[Category:Numismatics]] [[Category:Metallurgists|*]] {{Link FA|de}} [[ar:علم السبائك]] [[az:Metallurgiya]] [[bs:Metalurgija]] [[bg:Металургия]] [[ca:Metal·lúrgia]] [[cs:Metalurgie]] [[da:Metallurgi]] [[de:Metallurgie]] [[et:Metallurgia]] [[el:Μεταλλουργία]] [[es:Metalurgia]] [[eo:Metalurgio]] [[fa:متالورژی]] [[fr:Métallurgie]] [[gl:Metalurxia]] [[ko:금속공학]] [[hi:धातुकर्म]] [[hr:Metalurgija]] [[id:Metalurgi]] [[is:Málmfræði]] [[it:Metallurgia]] [[he:מטלורגיה]] [[lt:Metalurgija]] [[hu:Kohászat]] [[ms:Metalurgi]] [[nl:Metallurgie]] [[ja:金属工学]] [[no:Metallurgi]] [[pl:Metalurgia]] [[pt:Metalurgia]] [[ro:Metalurgie (industrie)]] [[qu:Q'illay llamk'ay]] [[ru:Металлургия]] [[simple:Metallurgy]] [[sk:Metalurgia]] [[sl:Metalurgija]] [[sr:Металургија]] [[sh:Metalurgija]] [[fi:Metallurgia]] [[sv:Metallurgi]] [[tl:Metalurhiya]] [[ta:உலோகவியல்]] [[th:วิศวกรรมโลหการ]] [[vi:Luyện kim]] [[tr:Metalürji]] [[uk:Металургія]] [[diq:Metallurciye]] [[zh:冶金学]]