Editing Alloy (section)

=== Iron ===
[[file:Chinese fining.png|thumb|Puddling in China, {{circa|1637}}. Opposite to most alloying processes, liquid pig-iron is poured from a blast furnace into a container and stirred to remove carbon, which diffuses into the air forming carbon dioxide, leaving behind a [[mild steel]] to wrought iron]]

The first known smelting of iron began in [[Anatolia]], around 1800 BC. Called the [[bloomery|bloomery process]], it produced very soft but [[ductile]] [[wrought iron]]. By 800 BC, iron-making technology had spread to Europe, arriving in Japan around 700 AD. [[Pig iron]], a very hard but brittle alloy of iron and carbon, was being produced in [[History of China#Shang dynasty (1600–1046 BC)|China]] as early as 1200 BC, but did not arrive in Europe until the Middle Ages. Pig iron has a lower melting point than iron, and was used for making [[cast-iron]]. However, these metals found little practical use until the introduction of [[crucible steel]] around 300 BC. These steels were of poor quality, and the introduction of [[pattern welding]], around the 1st century AD, sought to balance the extreme properties of the alloys by laminating them, to create a tougher metal. Around 700 AD, the Japanese began folding bloomery-steel and cast-iron in alternating layers to increase the strength of their swords, using clay fluxes to remove [[slag]] and impurities. This method of [[Japanese swordsmithing]] produced one of the purest steel-alloys of the ancient world.<ref name=r1>Smith, Cyril (1960) ''History of metallography''. MIT Press. pp. 2–4. {{ISBN|0-262-69120-5}}.</ref>

While the use of iron started to become more widespread around 1200 BC, mainly because of interruptions in the trade routes for tin, the metal was much softer than bronze. However, very small amounts of steel, (an alloy of iron and around 1% carbon), was always a byproduct of the bloomery process. The ability to modify the hardness of steel by heat treatment had been known since 1100 BC, and the rare material was valued for the manufacture of tools and weapons. Because the ancients could not produce temperatures high enough to melt iron fully, the production of steel in decent quantities did not occur until the introduction of [[blister steel]] during the Middle Ages. This method introduced carbon by heating wrought iron in charcoal for long periods of time, but the absorption of carbon in this manner is extremely slow thus the penetration was not very deep, so the alloy was not homogeneous. In 1740, [[Benjamin Huntsman]] began melting blister steel in a crucible to even out the carbon content, creating the first process for the mass production of [[tool steel]]. Huntsman's process was used for manufacturing tool steel until the early 1900s.<ref name="George Adam Roberts Page 2-3">Roberts, George Adam; Krauss, George; Kennedy, Richard and Kennedy, Richard L. (1998) [https://books.google.com/books?id=ScphevR_eP8C&pg=PA2 ''Tool steels''] {{webarchive|url=https://web.archive.org/web/20160424215509/https://books.google.com/books?id=ScphevR_eP8C&pg=PA2 |date=2016-04-24 }}. ASM International. pp. 2–3. {{ISBN|0-87170-599-0}}.</ref>

The introduction of the blast furnace to Europe in the Middle Ages meant that people could produce pig iron in much higher volumes than wrought iron. Because pig iron could be melted, people began to develop processes to reduce carbon in liquid pig iron to create steel. [[Puddling (metallurgy)|Puddling]] had been used in China since the first century, and was introduced in Europe during the 1700s, where molten pig iron was stirred while exposed to the air, to remove the carbon by [[oxidation]]. In 1858, [[Henry Bessemer]] developed a process of steel-making by blowing hot air through liquid pig iron to reduce the carbon content. The [[Bessemer process]] led to the first large scale manufacture of steel.<ref name="George Adam Roberts Page 2-3"/>

Steel is an alloy of iron and carbon, but the term ''[[alloy steel]]'' usually only refers to steels that contain other elements— like [[vanadium]], [[molybdenum]], or [[cobalt]]—in amounts sufficient to alter the properties of the base steel. Since ancient times, when steel was used primarily for tools and weapons, the methods of producing and working the metal were often closely guarded secrets. Even long after the [[Age of Enlightenment]], the steel industry was very competitive and manufacturers went through great lengths to keep their processes confidential, resisting any attempts to scientifically analyze the material for fear it would reveal their methods. For example, the people of [[Sheffield]], a center of steel production in England, were known to routinely bar visitors and tourists from entering town to deter [[industrial espionage]]. Thus, almost no metallurgical information existed about steel until 1860. Because of this lack of understanding, steel was not generally considered an alloy until the decades between 1930 and 1970 (primarily due to the work of scientists like [[William Chandler Roberts-Austen]], [[Adolf Martens]], and [[Edgar Bain]]), so "alloy steel" became the popular term for ternary and quaternary steel-alloys.<ref>''Sheffield Steel and America: A Century of Commercial and Technological Independence'' By Geoffrey Tweedale – Cambridge University Press 1987 Page 57–62</ref><ref>''Experimental Techniques in Materials and Mechanics'' By C. Suryanarayana – CRC Press 2011 p. 202</ref>

After Benjamin Huntsman developed his crucible steel in 1740, he began experimenting with the addition of elements like [[manganese]] (in the form of a high-manganese pig-iron called ''[[spiegeleisen]]''), which helped remove impurities such as phosphorus and oxygen; a process adopted by Bessemer and still used in modern steels (albeit in concentrations low enough to still be considered carbon steel).<ref>''Tool Steels, 5th Edition'' By George Adam Roberts, Richard Kennedy, G. Krauss – ASM International 1998 p. 4</ref> Afterward, many people began experimenting with various alloys of steel without much success. However, in 1882, [[Robert Hadfield]], being a pioneer in steel metallurgy, took an interest and produced a steel alloy containing around 12% manganese. Called [[mangalloy]], it exhibited extreme hardness and toughness, becoming the first commercially viable alloy-steel.<ref>{{cite book|author=Bramfitt, B.L.|title=Metallographer's Guide: Practice and Procedures for Irons and Steels|url=https://books.google.com/books?id=hoM8VJHTt24C&pg=PA13|year=2001|publisher=ASM International|isbn=978-1-61503-146-7|pages=13–|url-status=live|archive-url=https://web.archive.org/web/20160502154559/https://books.google.com/books?id=hoM8VJHTt24C&pg=PA13|archive-date=2016-05-02}}</ref> Afterward, he created silicon steel, launching the search for other possible alloys of steel.<ref>''Sheffield Steel and America: A Century of Commercial and Technological Independence'' By Geoffrey Tweedale – Cambridge University Press 1987 pp. 57–62</ref>

[[Robert Forester Mushet]] found that by adding [[tungsten]] to steel it could produce a very hard edge that would resist losing its hardness at high temperatures. "R. Mushet's special steel" (RMS) became the first [[high-speed steel]].<ref>''Sheffield Steel and America: A Century of Commercial and Technological Independence'' By Geoffrey Tweedale – Cambridge University Press 1987 pp. 66–68</ref> Mushet's steel was quickly replaced by [[tungsten carbide]] steel, developed by Taylor and White in 1900, in which they doubled the tungsten content and added small amounts of chromium and vanadium, producing a superior steel for use in lathes and machining tools. In 1903, the [[Wright brothers]] used a chromium-nickel steel to make the crankshaft for their airplane engine, while in 1908 [[Henry Ford]] began using vanadium steels for parts like crankshafts and valves in his [[Model T Ford]], due to their higher strength and resistance to high temperatures.<ref name="asmchandler">''Metallurgy for the Non-Metallurgist'' by Harry Chandler – ASM International 1998 Page 3–5</ref> In 1912, the Krupp Ironworks in Germany developed a rust-resistant steel by adding 21% chromium and 7% nickel, producing the first stainless steel.<ref>''Sheffield Steel and America: A Century of Commercial and Technological Independence'' By Geoffrey Tweedale – Cambridge University Press 1987 p. 75</ref>