View source for Chemistry:Metallurgy

{{short description|Field of science that studies the physical and chemical behavior of metals}}
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'''Metallurgy''' is a domain of [[Physics:Materials science|materials science and engineering]] that studies the physical and chemical behavior of [[Chemistry:Metal|metal]]lic [[Chemistry:Chemical element|elements]], their inter-metallic compounds, and their mixtures, which are known as [[Chemistry:Alloy|alloy]]s.

Metallurgy encompasses both the [[Science|science]] and the [[Engineering:Technology|technology]] of metals, including the production of [[Chemistry:Metal|metal]]s and the engineering of metal components used in products for both consumers and manufacturers. Metallurgy is distinct from the craft of [[Chemistry:Metalworking|metalworking]]. Metalworking relies on metallurgy in a similar manner to how [[Medicine:Medicine|medicine]] relies on medical science for technical advancement. A specialist [[Medicine:Practitioner–scholar model|practitioner]] of metallurgy is known as a metallurgist. 

The science of metallurgy is further subdivided into two broad categories: [[Engineering:Chemical metallurgy|chemical metallurgy]] and [[Physics:Physical metallurgy|physical metallurgy]]. Chemical metallurgy is chiefly concerned with the reduction and oxidation of metals, and the chemical performance of metals.  Subjects of study in chemical metallurgy include [[Chemistry:Mineral processing|mineral processing]], the [[Engineering:Extractive metallurgy|extraction of metals]], [[Physics:Thermodynamics|thermodynamics]], [[Chemistry:Electrochemistry|electrochemistry]], and chemical degradation ([[Chemistry:Corrosion|corrosion]]).<ref>{{Cite book|date=1990|title=Chemical Metallurgy|doi=10.1016/c2013-0-00969-3|isbn=978-0408053693|last1=Moore|first1=John Jeremy|last2=Boyce|first2=E. A.}}</ref>  In contrast, [[Physics:Physical metallurgy|physical metallurgy]] focuses on the mechanical properties of metals, the physical properties of metals, and the physical performance of metals. Topics studied in physical metallurgy include [[Physics:Crystallography|crystallography]], [[Physics:Characterization (materials science)|material characterization]], mechanical metallurgy, [[Physics:Phase transition|phase transformations]], and [[Physics:Metallurgical failure analysis|failure mechanisms]].<ref>{{Cite book|url=https://books.google.com/books?id=TNDKCgAAQBAJ|title=Physical Metallurgy: Principles and Practice|edition=3rd|last=Raghavan|first=V|publisher=PHI Learning|year=2015|isbn=978-8120351707|access-date=20 September 2020|archive-date=24 June 2021|archive-url=https://web.archive.org/web/20210624195141/https://books.google.com/books?id=TNDKCgAAQBAJ|url-status=live}}</ref>  

Historically, metallurgy has predominately focused on the production of metals. Metal production begins with the processing of [[Earth:Ore|ore]]s to extract the metal, and includes the mixture of metals to make [[Chemistry:Alloy|alloy]]s. Metal alloys are often a blend of at least two different metallic elements. However, non-metallic elements are often added to alloys in order to achieve properties suitable for an application. The study of metal production is subdivided into [[Engineering:Ferrous metallurgy|ferrous metallurgy]] (also known as ''black metallurgy'') and non-ferrous metallurgy, also known as colored metallurgy.

Ferrous metallurgy involves processes and alloys based on [[Chemistry:Iron|iron]], while non-ferrous metallurgy involves processes and alloys based on other metals. The production of ferrous metals accounts for 95% of world metal production.<ref>[http://dic.academic.ru/dic.nsf/bse/108584/%D0%9C%D0%B5%D1%82%D0%B0%D0%BB%D0%BB%D1%83%D1%80%D0%B3%D0%B8%D1%8F "Металлургия"] {{Webarchive|url=https://web.archive.org/web/20150118031950/http://dic.academic.ru/dic.nsf/bse/108584/%D0%9C%D0%B5%D1%82%D0%B0%D0%BB%D0%BB%D1%83%D1%80%D0%B3%D0%B8%D1%8F |date=18 January 2015 }}. in ''The [[Great Soviet Encyclopedia]]''. 1979.</ref>

Modern metallurgists work in both emerging and traditional areas as part of an interdisciplinary team alongside material scientists and other engineers. Some traditional areas include mineral processing, metal production, heat treatment, [[Physics:Metallurgical failure analysis|failure analysis]], and the joining of metals (including [[Chemistry:Welding|welding]], [[Engineering:Brazing|brazing]], and [[Physics:Soldering|soldering]]).  Emerging areas for metallurgists include [[Engineering:Nanotechnology|nanotechnology]], [[Physics:Superconductivity|superconductors]], [[Chemistry:Composite material|composites]], [[Chemistry:Biomaterial|biomedical materials]], electronic materials (semiconductors) and [[Physics:Surface engineering|surface engineering]]. Many applications, practices, and devices associated or involved in metallurgy were established in ancient India and China, such as the innovation of the wootz steel , [[Chemistry:Bronze|bronze]], [[Engineering:Blast furnace|blast furnace]], [[Chemistry:Cast iron|cast iron]], hydraulic-powered [[Engineering:Trip hammer|trip hammer]]s, and double acting piston [[Engineering:Bellows|bellows]].<ref name="auto">R. F. Tylecote (1992) ''A History of Metallurgy'' {{ISBN|0901462888}}</ref><ref name="temple-r">Robert K.G. Temple (2007). ''The Genius of China: 3,000 Years of Science, Discovery, and Invention'' (3rd ed.). London: André Deutsch. pp. 44–56. {{ISBN|978-0233002026}}.</ref>

==Etymology and pronunciation==
''Metallurgy'' derives from the [[Social:Ancient Greek|Ancient Greek]] {{lang|grc|μεταλλουργός}}, {{transl|grc|metallourgós}}, "worker in metal", from {{lang|grc|μέταλλον}}, {{transl|grc|métallon}}, "mine, metal" + {{lang|grc|ἔργον}}, {{transl|grc|érgon}}, "work" The word was originally an alchemist's term for the extraction of metals from minerals, the ending ''-urgy'' signifying a process, especially manufacturing: it was discussed in this sense in the 1797 ''[[Encyclopædia Britannica]]''.<ref>{{cite dictionary |dictionary=Oxford Learner's Dictionary |access-date=29 January 2011 |title=metallurgy |url=https://www.oxfordlearnersdictionaries.com/definition/english/metallurgy |publisher=[[Organization:Oxford University Press|Oxford University Press]] |archive-date=1 August 2014 |archive-url=https://web.archive.org/web/20140801110336/http://www.oxfordlearnersdictionaries.com/definition/english/metallurgy |url-status=live }}</ref>

In the late 19th century, metallurgy's definition was extended to the more general scientific study of metals, alloys, and related processes. In [[Social:English language|English]], the {{IPAc-en|m|ɛ|ˈ|t|æ|l|ər|dʒ|i}} pronunciation is the more common one in the {{wipe|United Kingdom}}. The {{IPAc-en|ˈ|m|ɛ|t|əl|ɜːr|dʒ|i}} pronunciation is the more common one in the {{wipe|United States}} US and is the first-listed variant in various American dictionaries, including ''Merriam-Webster Collegiate'' and ''American Heritage''.

==History==
{{See also|Alchemy|Chalcolithic|Bronze Age|History of ferrous metallurgy|Mining and metallurgy in medieval Europe|Metallurgy in pre-Columbian America|Metallurgy in pre-Columbian Mesoamerica|Copper metallurgy in Africa|Iron metallurgy in Africa|Copper metallurgy in Africa|History of metallurgy in the Indian subcontinent|Non-ferrous extractive metallurgy|}}[[File:Grave offerings.jpg|thumb|Artefacts from the Varna Necropolis in present-day Bulgaria]]
[[File:Metal production in Ancient Middle East.svg|thumb|The mining areas of the ancient Middle East with arsenic (in brown), copper (in red), tin (in grey), iron (in reddish brown), gold (in yellow), silver (in white), lead (in black), arsenic bronze (in yellow), and tin (in bronze)]]
The earliest recorded metal employed by humans appears to be [[Chemistry:Gold|gold]], which can be found [[Chemistry:Native metal|free]] or "[[Chemistry:Native metal|native]]". Small amounts of natural gold have been found in Spanish caves dating to the late [[Earth:Paleolithic|Paleolithic]] period, 40,000 BC.<ref>{{cite web | url = http://www.gold-eagle.com/gold_digest/history_gold.html | title = History of Gold | publisher = Gold Digest | access-date = 2007-02-04 | archive-date = 29 April 2007 | archive-url = https://web.archive.org/web/20070429150255/http://www.gold-eagle.com/gold_digest/history_gold.html | url-status = live }}</ref> [[Chemistry:Silver|Silver]], [[Chemistry:Copper|copper]], [[Chemistry:Tin|tin]] and meteoric [[Chemistry:Iron|iron]] can also be found in native form, allowing a limited amount of [[Chemistry:Metalworking|metalworking]] in early cultures.<ref name=ephotos>{{cite journal|author=E. Photos, E.|title=The Question of Meteoritic versus Smelted Nickel-Rich Iron: Archaeological Evidence and Experimental Results|journal=World Archaeology|volume=20|issue=3|pages=403–421|jstor=124562|doi=10.1080/00438243.1989.9980081|url=http://img2.tapuz.co.il/forums/1_132972987.pdf|year=2010|access-date=1 January 2015|archive-date=22 December 2015|archive-url=https://web.archive.org/web/20151222133855/http://img2.tapuz.co.il/forums/1_132972987.pdf|url-status=live}}</ref> 

Certain metals, such as tin, lead, and copper can be recovered from their ores by simply heating the rocks in a fire or blast furnace in a process known as [[Engineering:Smelting|smelting]]. The first evidence of this extractive metallurgy, dating from the 5th and 6th millennia&nbsp;BC,<ref>[https://www.crcpress.com/New-Developments-in-Mining-Engineering-2015-Theoretical-and-Practical-Solutions/Bondarenko-Kovalevska-Pivnyak/9781138028838 H.I. Haiko, V.S. Biletskyi. First metals discovery and development the sacral component phenomenon. // Theoretical and Practical Solutions of Mineral Resources Mining // A Balkema Book, London, 2015, р. 227-233.] {{Webarchive|url=https://web.archive.org/web/20151208154730/https://www.crcpress.com/New-Developments-in-Mining-Engineering-2015-Theoretical-and-Practical-Solutions/Bondarenko-Kovalevska-Pivnyak/9781138028838 |date=8 December 2015 }}.</ref> has been found at archaeological sites in Majdanpek, Jarmovac and Pločnik, in present-day Serbia.<ref>{{cite journal | journal = Journal of World Prehistory | year = 2021 | issue = 2 | title = Early Balkan Metallurgy: Origins, Evolution and Society, 6200–3700 BC | first1 = Miljana | last1 = Radivojević | first2 = Benjamin W. | last2 = Roberts | volume = 34 | pages = 195–278 | doi = 10.1007/s10963-021-09155-7 | s2cid = 237005605 | doi-access = free }}</ref> 

The earliest evidence of copper smelting is found at the Belovode site near Pločnik.<ref>{{cite journal|doi=10.1016/j.jas.2010.06.012|title=On the origins of extractive metallurgy: New evidence from Europe|year=2010|last1=Radivojević|first1=Miljana|last2=Rehren|first2=Thilo|last3=Pernicka|first3=Ernst|last4=Šljivar|first4=Dušan|last5=Brauns|first5=Michael|last6=Borić|first6=Dušan|journal=Journal of Archaeological Science|volume=37|issue=11|pages=2775}}
</ref> The site produced a copper axe from 5,500 BC, belonging to the [[History:Vinča culture|Vinča culture]].<ref>[http://www.stonepages.com/news/archives/002605.html Neolithic Vinca was a metallurgical culture] {{Webarchive|url=https://web.archive.org/web/20170919043337/http://www.stonepages.com/news/archives/002605.html |date=19 September 2017 }} Stonepages from news sources November 2007</ref>

The earliest use of lead was in the late [[History:Neolithic|neolithic]] settlements of Yarim Tepe and Arpachiyah in present-day Iraq. The artifacts suggest that lead smelting predated copper smelting.<ref name="Potts 2012 p. 302">{{cite book | last=Potts | first=D.T. | title=A Companion to the Archaeology of the Ancient Near East | publisher=Wiley | series=Blackwell Companions to the Ancient World | year=2012 | isbn=978-1444360776 | url=https://books.google.com/books?id=P5q7DDqMbF0C&pg=PA302 | access-date=2022-03-19 | pages=302–303 | archive-date=21 September 2020 | archive-url=https://web.archive.org/web/20200921233111/https://books.google.com/books?id=P5q7DDqMbF0C&pg=PA302 | url-status=live }}</ref>

Copper smelting is also documented at this site at about the same time period (soon after 6,000 BC), although the use of lead seems to precede copper smelting. Early metallurgy is also documented at the nearby site of Tell Maghzaliyah, which seems to be dated even earlier, and completely lacks that pottery.{{Citation needed|date=September 2020}} The Balkans were the site of major Neolithic cultures, including Butmir, Vinča, Varna, [[History:Karanovo culture|Karanovo]], and [[History:Hamangia culture|Hamangia]].

The [[Social:Varna Necropolis|Varna Necropolis]], Bulgaria, is a burial site in the western industrial zone of [[Place:Varna, Bulgaria|Varna]], approximately 4&nbsp;km from the city centre, internationally considered one of the key archaeological sites in world prehistory. The oldest [[Chemistry:Gold|gold]] treasure in the world, dating from 4,600 BC to 4,200 BC, was discovered at the site.<ref>[https://books.google.com/books?id=RnE9Fa4pbn0C&dq=varna+necropolis+oldest&pg=PA290] {{Webarchive|url=https://web.archive.org/web/20200212191629/https://books.google.com/books?id=RnE9Fa4pbn0C&pg=PA290&dq=varna+necropolis+oldest&hl=en#v=onepage&q=varna%20necropolis%20oldest&f=false|date=12 February 2020}} Gems and Gemstones: Timeless Natural Beauty of the Mineral World, By Lance Grande</ref> The gold piece dating from 4,500 BC, found in 2019 in Durankulak, near [[Place:Varna, Bulgaria|Varna]] is another important example.<ref>{{Cite web|url=https://europost.eu/en/a/view/world-s-oldest-gold-24581|title=World's oldest gold|access-date=28 September 2019|archive-date=28 September 2019|archive-url=https://web.archive.org/web/20190928002450/https://europost.eu/en/a/view/world-s-oldest-gold-24581|url-status=live}}</ref><ref>{{Cite web|url=https://www.smithsonianmag.com/smart-news/oldest-gold-object-unearthed-bulgaria-180960093/|title=World's Oldest Gold Object May Have Just Been Unearthed in Bulgaria|first1=Smithsonian|last1=Magazine|first2=Jason|last2=Daley|website=Smithsonian Magazine|access-date=28 September 2019|archive-date=28 September 2019|archive-url=https://web.archive.org/web/20190928002452/https://www.smithsonianmag.com/smart-news/oldest-gold-object-unearthed-bulgaria-180960093/|url-status=live}}</ref>  Other signs of early metals are found from the third millennium&nbsp;BC in Palmela, Portugal, Los Millares, Spain, and [[Unsolved:Stonehenge|Stonehenge]], United Kingdom. The precise beginnings, however, have not be clearly ascertained and new discoveries are both continuous and ongoing.

In approximately 1900 BC, ancient iron smelting sites existed in Tamil Nadu. <ref>{{cite web|url=https://indianexpress.com/article/explained/tamil-nadu-iron-usage-carbon-dating-cultural-significance-explained-7916375/|title=Ancient Smelting in Tamil Nadu India|website=www.indianexpress.com|access-date=27 October 2023|archive-date=4 October 2022|archive-url=https://web.archive.org/web/20221004181810/https://indianexpress.com/article/explained/tamil-nadu-iron-usage-carbon-dating-cultural-significance-explained-7916375/|url-status=live}}</ref> <ref>{{cite web|url=https://currentscience.ac.in/Volumes/121/02/0239.pdf|title=Ancient high-carbon steel from southern Tamil Nadu India microstructural and elemental analysis|website=www.currentscience.ac.in|access-date=27 October 2023|archive-date=20 June 2023|archive-url=https://web.archive.org/web/20230620230643/https://currentscience.ac.in/Volumes/121/02/0239.pdf|url-status=live}}</ref>

In the [[History:Ancient Near East|Near East]], about 3,500 BC, it was discovered that by combining copper and tin, a superior metal could be made, an [[Chemistry:Alloy|alloy]] called [[Chemistry:Bronze|bronze]]. This represented a major technological shift known as the [[History:Bronze Age|Bronze Age]].

The extraction of [[Chemistry:Iron|iron]] from its ore into a workable metal is much more difficult than for copper or tin. The process appears to have been invented by the [[History:Hittites|Hittites]] in about 1200&nbsp;BC, beginning the [[History:Iron Age|Iron Age]]. The secret of extracting and working iron was a key factor in the success of the Philistines.<ref name=keller>W. Keller (1963) ''The Bible as History''. p. 156. {{ISBN|034000312X}}</ref><ref>B. W. Anderson (1975) ''The Living World of the Old Testament'', p. 154, {{ISBN|0582485983}}</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 [[Place:Middle East|Middle East]] and [[Place:Near East|Near East]], ancient [[Religion:Iran|Iran]], ancient [[Place:Egypt|Egypt]], ancient [[Place:Nubia|Nubia]], and [[Earth:Anatolia|Anatolia]] in present-day [[Place:Turkey|Turkey]], Ancient Nok, Carthage, the Greeks and [[History:Ancient Rome|Romans]] of ancient [[Earth:Europe|Europe]], medieval Europe, ancient and medieval {{wipe|China}}, ancient and medieval {{wipe|India}}, ancient and medieval {{wipe|Japan}}, amongst others. Many applications, practices, and devices associated or involved in metallurgy were established in ancient China, such as the innovation of the [[Engineering:Blast furnace|blast furnace]], [[Chemistry:Cast iron|cast iron]], hydraulic-powered [[Engineering:Trip hammer|trip hammer]]s, and double acting piston [[Engineering:Bellows|bellows]].<ref name="auto"/><ref name="temple-r"/>

A 16th century book by Georg Agricola, ''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>{{cite book|author=Karl Alfred von Zittel|year=1901|title=HISTORY of Geology and Palaeontology|page=15|url=http://www.geology.19thcenturyscience.org/books/1901-Zittel-HistGeol/htm/doc.html|doi=10.5962/bhl.title.33301|access-date=1 January 2015|archive-url=https://web.archive.org/web/20160304030840/http://www.geology.19thcenturyscience.org/books/1901-Zittel-HistGeol/htm/doc.html|archive-date=4 March 2016|url-status=dead}}</ref>

==Extraction==
{{main|Engineering:Extractive metallurgy}}
[[File:Yuan Dynasty - waterwheels and smelting.png|thumb|An illustration of a furnace bellows operated by waterwheels during the Yuan Dynasty in China]]
[[Engineering:Extractive metallurgy|Extractive metallurgy]] is the practice of removing valuable metals from an [[Earth:Ore|ore]] and refining the extracted raw metals into a purer form. In order to convert a metal [[Chemistry:Oxide|oxide]] or [[Chemistry:Sulfide|sulphide]] to a purer metal, the ore must be [[Chemistry:Redox|reduced]] physically, [[Chemistry:Chemistry|chemically]], or [[Physics:Electrolyte|electrolytically]]. Extractive metallurgists are interested in three primary streams: feed, concentrate (metal oxide/sulphide) and [[Engineering:Tailings|tailings]] (waste).

After mining, large pieces of the ore feed are broken through crushing or grinding in order to obtain particles small enough, where each particle is either mostly valuable or mostly waste. Concentrating the particles of 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 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.

==Metal and its alloys==
{{Main|Chemistry:Metal|Chemistry:Alloy}}
[[File:Iron electrolytic and 1cm3 cube.jpg|thumb|[[Chemistry:Iron|Iron]], the most common metal used in metallurgy, is shown in different forms, including cubes, chips, and nuggets]]
Much effort has been placed on understanding [[Chemistry:Iron|iron]]–carbon alloy system, which includes steels and [[Chemistry:Cast iron|cast iron]]s. [[Engineering:Carbon steel|Plain carbon steels]] (those that contain essentially only carbon as an alloying element) are used in low-cost, high-strength applications, where neither weight nor [[Chemistry:Corrosion|corrosion]] are a major concern. Cast irons, including [[Chemistry:Ductile iron|ductile iron]], are also part of the iron-carbon system.  Iron-Manganese-Chromium alloys (Hadfield-type steels) are also used in non-magnetic applications such as directional drilling.

Other engineering [[Chemistry:Metal|metal]]s include [[Chemistry:Aluminium|aluminium]], [[Chemistry:Chromium|chromium]], [[Chemistry:Copper|copper]], [[Chemistry:Magnesium|magnesium]], [[Chemistry:Nickel|nickel]], [[Chemistry:Titanium|titanium]], [[Chemistry:Zinc|zinc]], and [[Chemistry:Silicon|silicon]]. These metals are most often used as alloys with the noted exception of silicon, which is not a metal. Other forms include:

* Aluminium alloys and magnesium alloys are commonly used, when a lightweight strong part is required such as in automotive and aerospace applications.
* Copper-nickel alloys (such as [[Chemistry:Monel|Monel]]) are used in highly corrosive environments and for non-magnetic applications.
* Nickel-based [[Chemistry:Superalloy|superalloy]]s like [[Chemistry:Inconel|Inconel]] are used in high-temperature applications such as [[Engineering:Gas turbine|gas turbine]]s, [[Engineering:Turbocharger|turbocharger]]s, [[Physics:Pressure vessel|pressure vessel]]s, and [[Physics:Heat exchanger|heat exchanger]]s.
* For extremely high temperatures, [[Earth:Single crystal|single crystal]] alloys are used to minimize [[Physics:Creep (deformation)|creep]]. In modern electronics, high purity single crystal silicon is essential for [[Engineering:MOSFET|metal-oxide-silicon]] transistors (MOS) and [[Engineering:Integrated circuit|integrated circuit]]s.

==Production==
In [[Industrial engineering|production engineering]], metallurgy is concerned with the production of metallic components for use in consumer or [[Engineering:Engineering|engineering]] products. This involves production of alloys, shaping, heat treatment and surface treatment of product. The task of the metallurgist is to achieve balance between material properties, such as cost, [[Physics:Weight|weight]], [[Physics:Tensile strength|strength]], [[Physics:Toughness|toughness]], hardness, [[Chemistry:Corrosion|corrosion]], [[Fatigue (material)|fatigue]] resistance and performance in [[Physics:Temperature|temperature]] extremes. To achieve this goal, the operating environment must be carefully considered.{{Cn|date=August 2022}}

Determining the hardness of the metal using the Rockwell, Vickers, and Brinell hardness scales is a commonly used practice that helps better understand the metal's elasticity and plasticity for different applications and production processes.<ref>{{Cite news |date=2017-06-14 |title=Metal Hardness Tests: Difference Between Rockwell, Brinell, and Vickers |language=en-US |work=ESI Engineering Specialties Inc. |url=https://www.esict.com/blog/rockwell-brinell-and-vickers-metal-hardness |url-status=live |access-date=2017-12-13 |archive-url=https://web.archive.org/web/20171214014727/https://www.esict.com/blog/rockwell-brinell-and-vickers-metal-hardness |archive-date=14 December 2017}}</ref> In a saltwater environment, most ferrous metals and some non-ferrous alloys corrode quickly. Metals exposed to cold or cryogenic conditions may undergo a ductile to brittle transition and lose their toughness, becoming more brittle and prone to cracking. Metals under continual cyclic loading can suffer from [[Fatigue (material)|metal fatigue]]. Metals under constant [[Physics:Stress|stress]] at elevated temperatures can [[Physics:Creep (deformation)|creep]].

===Metalworking processes===
{{Main|Chemistry:Metalworking}}
[[File:Bochumer Verein-08-50124.jpg|thumb|An open-die drop forging with two dies of an ingot, which is then further processed into a wheel]]
* [[Engineering:Casting (metalworking)|Casting]] – molten metal is poured into a shaped [[Engineering:Molding (process)|mold]]. Variants of casting include sand casting, [[Engineering:Investment casting|investment casting]], also called the lost wax process, die casting, and continuous castings. Each of these forms has advantages for certain metals and applications considering factors like magnetism and corrosion.<ref>{{Cite web |title=Casting Process, Types of Casting Process, Casting Process Tips, Selecting Casting Process, Casting Process Helps |url=http://www.themetalcasting.com/casting-process.html |url-status=live |archive-url=https://web.archive.org/web/20171218093932/http://www.themetalcasting.com/casting-process.html |archive-date=18 December 2017 |access-date=2017-12-13 |website=www.themetalcasting.com |language=en}}</ref>
* [[Engineering:Forging|Forging]] – a red-hot billet is hammered into shape.
* [[Engineering:Rolling (metalworking)|Rolling]] – a billet is passed through successively narrower rollers to create a sheet.
* [[Chemistry:Extrusion|Extrusion]] – a hot and malleable metal is forced under pressure through a [[Engineering:Die (manufacturing)|die]], which shapes it before it cools.
* [[Engineering:Machining|Machining]] – lathes, milling machines and [[Engineering:Drill|drill]]s cut the cold metal to shape.
* [[Earth:Sintering|Sintering]] – a [[Engineering:Powder metallurgy|powdered metal]] is heated in a non-oxidizing environment after being compressed into a die.
* Fabrication – sheets of metal are cut with [[Engineering:Guillotine|guillotine]]s or gas cutters and bent and welded into structural shape.
* [[Physics:Cladding (metalworking)|Laser cladding]] – metallic powder is blown through a movable laser beam (e.g. mounted on a NC 5-axis machine). The resulting melted metal reaches a substrate to form a melt pool. By moving the laser head, it is possible to stack the tracks and build up a three-dimensional piece.
* [[3D printing|3D printing]] – Sintering or melting amorphous powder metal in a 3D space to make any object to shape.

[[Engineering:Cold working|Cold-working]] processes, in which 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 [[Engineering:Work hardening|work hardening]]. Work hardening creates microscopic defects in the metal, which resist further changes of shape.

===Heat treatment===
[[File:Heat-Treating-Furnace.jpg|thumb|A heat treating furnace at {{convert|1800|F|abbr=on}}]]
Metals can be heat-treated to alter the properties of strength, ductility, toughness, hardness and resistance to corrosion. Common heat treatment processes include annealing, precipitation strengthening, quenching, and tempering:<ref>Arthur Reardon (2011), ''Metallurgy for the Non-Metallurgist'' (2nd ed.), ASM International, {{ISBN|978-1615038213}}</ref>
* [[Engineering:Annealing (metallurgy)|Annealing]] process softens the metal by heating it and then allowing it to cool very slowly, which gets rid of stresses in the metal and makes the grain structure large and soft-edged so that, when the metal is hit or stressed it dents or perhaps bends, rather than breaking; it is also easier to sand, grind, or cut annealed metal.
* [[Engineering:Quenching|Quenching]] is the process of cooling metal very quickly after heating, thus "freezing" the metal's molecules in the very hard martensite form, which makes the metal harder.
* [[Engineering:Tempering (metallurgy)|Tempering]] relieves stresses in the metal that were caused by the hardening process; tempering makes the metal less hard while making it better able to sustain impacts without breaking.

Often, mechanical and thermal treatments are combined in what are known as thermo-mechanical treatments for better properties and more efficient processing of materials. These processes are common to high-alloy special steels, [[Chemistry:Superalloy|superalloy]]s and titanium alloys.

===Plating===
{{Main|Physics:Plating}}
[[File:Copper electroplating principle (multilingual).svg|thumb|A simplified diagram of electroplating copper on a metal]]
[[Engineering:Electroplating|Electroplating]] is a chemical surface-treatment technique. It involves bonding a thin layer of another metal such as [[Chemistry:Gold|gold]], [[Chemistry:Silver|silver]], [[Chemistry:Chromium|chromium]] or [[Chemistry:Zinc|zinc]] to the surface of the product. This is done by selecting the coating material electrolyte solution, which is the material that is going to coat the workpiece (gold, silver, zinc). There needs to be two electrodes of different materials: one the same material as the coating material and one that is receiving the coating material. Two electrodes are electrically charged and the coating material is stuck to the work piece. It is used to reduce corrosion as well as to improve the product's aesthetic appearance. It is also used to make inexpensive metals look like the more expensive ones (gold, silver).<ref>{{cite web |url=http://www.explainthatstuff.com/electroplating.html |title=How electroplating works |work=Explain that Stuff |first=Chris |last=Woodford|year=2017 |access-date=20 May 2019 |archive-date=15 June 2019 |archive-url=https://web.archive.org/web/20190615083919/https://www.explainthatstuff.com/electroplating.html |url-status=live }}</ref>

=== Shot peening ===
{{main|Engineering:Shot peening}}
Shot peening is a cold working process used to finish metal parts. In the process of shot peening, small round shot is blasted against the surface of the part to be finished. This process is used to prolong the product life of the part, prevent stress corrosion failures, and also prevent fatigue. The shot leaves small dimples on the surface like a peen hammer does, which cause compression stress under the dimple. As the shot media strikes the material over and over, it forms many overlapping dimples throughout the piece being treated. The compression stress in the surface of the material strengthens the part and makes it more resistant to fatigue failure, stress failures, corrosion failure, and cracking.<ref>{{cite web|url=https://www.engineeredabrasives.com/what-is-shot-peening.html|title=What is Shot Peening – How Does Shot Peening Work|website=www.engineeredabrasives.com|access-date=4 January 2019|archive-date=12 June 2018|archive-url=https://web.archive.org/web/20180612162445/https://www.engineeredabrasives.com/what-is-shot-peening.html|url-status=live}}</ref>

===Thermal spraying===
{{Main|Physics:Thermal spraying}}
Thermal spraying techniques are another popular finishing option, and often have better high temperature properties than electroplated coatings. Thermal spraying, also known as a spray welding process,<ref>{{Cite web|url=http://www.precisioncoatings.com/what-is-thermal-spray.html|title=Thermal Spray, Plasma Spray, HVOF, Flame Spray, Metalizing & Thermal Spray Coating|location=Saint Paul, MN|website=www.precisioncoatings.com|access-date=2017-12-13|archive-date=14 August 2022|archive-url=https://web.archive.org/web/20220814091513/https://www.precisioncoatings.com/what-is-thermal-spray/|url-status=live}}</ref> is an industrial coating process that consists of a heat source (flame or other) and a coating material that can be in a powder or wire form, which is melted then sprayed on the surface of the material being treated at a high velocity. The spray treating process is known by many different names such as HVOF (High Velocity Oxygen Fuel), plasma spray, flame spray, arc spray and metalizing.

=== Electroless deposition ===
{{Main article|Engineering:Electroless deposition}}
Electroless deposition (ED) or electroless plating is defined as the [[Chemistry:Autocatalysis|autocatalytic process]] through which metals and metal alloys are deposited onto nonconductive surfaces.These nonconductive surfaces include plastics, ceramics, and glass etc., which can then become decorative, anti-corrosive, and conductive depending on their final functions. Electroless deposition is a chemical processes that create [[Chemistry:Metal|metal]] coatings on various materials by [[Chemistry:Autocatalysis|autocatalytic]] chemical reduction of metal cations in a liquid bath.

==Characterization==
[[File:AlubronzeCuAl20v500.png|thumb|Metallography allows the metallurgist to study the microstructure of metals.]] Metallurgists study the microscopic and macroscopic structure of metals using [[Engineering:Metallography|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. The sample is then examined in an optical or [[Engineering:Electron microscope|electron microscope]], and the image contrast provides details on the composition, mechanical properties, and processing history.

[[Physics:Crystallography|Crystallography]], often using [[Physics:Diffraction|diffraction]] of [[Physics:X-ray|x-ray]]s or [[Physics:Electron|electron]]s, is another valuable tool available to the modern metallurgist. Crystallography allows 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.

==See also==
{{Div col|small=no}}
* Adrien Chenot
* Archaeometallurgy
* CALPHAD
* [[Chemistry:Carbonyl metallurgy|Carbonyl metallurgy]]
* [[Engineering:Cupellation|Cupellation]]
* [[Engineering:Experimental archaeometallurgy|Experimental archaeometallurgy]]
* [[Chemistry:Goldbeating|Goldbeating]]
* Gold phosphine complex
* [[Physics:Metallurgical failure analysis|Metallurgical failure analysis]]
* Mineral industry
* [[Engineering:Pyrometallurgy|Pyrometallurgy]]
{{Div col end}}

==References==
{{reflist|30em}}


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[[Category:Metallurgy| ]]
[[Category:Metals]]

{{Sourceattribution|Metallurgy}}