Editing Titanium (section)

==Fabrication==
[[File:Evolution Ti.jpg|thumb|right|Market price of Titanium]]
All [[welding]] of titanium must be done in an inert atmosphere of argon or [[helium]] to shield it from contamination with atmospheric gases (oxygen, nitrogen, and hydrogen).<ref name=Barksdale1968p734/> Contamination causes a variety of conditions, such as [[embrittlement]], which reduce the integrity of the assembly welds and lead to joint failure.<ref>{{Cite book |year=1955 |title=Arc-welding Titanium |author1= Engel, Abraham L. |author2=Huber, R.W. |author3=Lane, I.R. |publisher=U.S. Department of the Interior, Bureau of Mines }}</ref>

Titanium is very difficult to [[solder]] directly, and hence a [[solderability|solderable]] metal or alloy such as steel is coated on titanium prior to soldering.<ref>{{cite book | title=Report on Brazing and Soldering of Titanium |year=1956 |publisher=Titanium Metallurgical Laboratory, Battelle Memorial Institute |author1=Lewis, W.J. |author2=Faulkner, G.E. |author3=Rieppel, P.J. | url=https://books.google.com/books?id=316b7CW_HOMC&dq=Titanium+soldering&pg=PA2}}</ref> Titanium metal can be machined with the same equipment and the same processes as [[stainless steel]].<ref name="Barksdale1968p734" />

===Titanium alloys===
{{main|Titanium alloys}}
[[File:Titanium products.jpg|thumb|Basic titanium products: plate, tube, rods, and powder]]
Common [[titanium alloy]]s are made by reduction. For example, cuprotitanium (rutile with [[copper]] added), ferrocarbon titanium (ilmenite reduced with [[coke (fuel)|coke]] in an electric furnace), and manganotitanium (rutile with manganese or manganese oxides) are reduced.<ref name=TI_Encarta2005>{{cite encyclopedia |title=Titanium |year=2005 |encyclopedia=Microsoft Encarta |url=http://encarta.msn.com/encyclopedia_761569280/Titanium.html |access-date=29 December 2006  |archive-url= https://web.archive.org/web/20061027112633/http://encarta.msn.com/encyclopedia_761569280/Titanium.html |archive-date=27 October 2006}}</ref>

About fifty grades of [[titanium alloy]]s are designed and currently used, although only a couple of dozen are readily available commercially.<ref>{{harvnb|Donachie|1988|p=16, Appendix&nbsp;J}}</ref> The [[ASTM International]] recognizes 31&nbsp;grades of titanium metal and alloys, of which grades one through four are commercially pure (unalloyed). Those four vary in tensile strength as a function of oxygen content, with grade 1 being the most ductile (lowest tensile strength with an oxygen content of 0.18%), and grade&nbsp;4 the least ductile (highest tensile strength with an oxygen content of 0.40%).<ref name=Emsley2001p453/> The remaining grades are alloys, each designed for specific properties of ductility, strength, hardness, electrical resistivity, [[creep (deformation)|creep]] resistance, specific corrosion resistance, and combinations thereof.<ref>{{cite book |title=Annual Book of ASTM Standards |section=Volume&nbsp;02.04: Non-ferrous Metals |year=2006 |publisher=[[ASTM International]] |location=[[West Conshohocken, PA]] |at=section&nbsp;2 |isbn=978-0-8031-4086-8 |url=https://books.google.com/books?id=yCGIPQAACAAJ}} {{cite book |title=Annual Book of ASTM Standards |year=1998 |section=Volume&nbsp;13.01: Medical Devices; Emergency Medical Services |publisher=[[ASTM International]] |location=[[West Conshohocken, PA]] |at=sections&nbsp;2 & 13 |isbn=978-0-8031-2452-3}}</ref>

In addition to the ASTM specifications, titanium alloys are also produced to meet aerospace and military specifications (SAE-AMS, MIL-T), ISO standards, and country-specific specifications, as well as proprietary end-user specifications for aerospace, military, medical, and industrial applications.<ref>{{harvnb|Donachie|1988|pp=13–16, Appendices H and J}}</ref>

===Forming and forging===
Commercially pure flat product (sheet, plate) can be formed readily, but processing must take into account of the tendency of the metal to [[springback]]. This is especially true of certain high-strength alloys.<ref>{{cite book|title=AWS G2.4/G2.4M:2007 Guide for the Fusion Welding of Titanium and Titanium Alloys |year=2006 |publisher=American Welding Society |place=Miami |url=http://pdfcast.org/pdf/titanium-design-and-fabrication-handbook-for-industrial-applications |archive-url=https://web.archive.org/web/20101210022045/http://pdfcast.org/pdf/titanium-design-and-fabrication-handbook-for-industrial-applications |archive-date=10 December 2010 }}</ref><ref>{{cite book|title=Titanium design and fabrication handbook for industrial applications |year=1997 |publisher=Titanium Metals Corporation |location=Dallas |url=http://www.timet.com/design%26fabframe.html |author-link=Titanium Metals Corporation |archive-url=https://web.archive.org/web/20090209014255/http://www.timet.com/design%26fabframe.html |archive-date=9 February 2009 }}</ref> Exposure to the oxygen in air at the elevated temperatures used in forging results in formation of a brittle oxygen-rich metallic surface layer called "[[alpha case]]" that worsens the fatigue properties, so it must be removed by milling, etching, or electrochemical treatment.<ref name='"Chen 2001"'>{{cite journal |last1=Chen |first1=George Z. |last2=Fray |first2=Derek J. |last3=Farthing |first3=Tom W. |year=2001 |title=Cathodic deoxygenation of the alpha case on titanium and alloys in molten calcium chloride |journal=Metall. Mater. Trans.&nbsp;B |volume=32 |issue=6 |pages=1041–1052 |doi=10.1007/s11663-001-0093-8 |bibcode=2001MMTB...32.1041C |s2cid=95616531 |url=https://link.springer.com/article/10.1007/s11663-001-0093-8|url-access=subscription }}</ref> The working of titanium is very complicated,<ref name="tm1">{{cite news |url=https://www.totalmateria.com/en-us/articles/fabrication-of-titanium-and-titanium-alloys/ |title=Fabrication of Titanium and Titanium Alloys &#124; Total Materia }}</ref><ref name="tig1">{{cite news |url=https://www.titaniuminfogroup.com/forging-process-of-titanium-alloy.html |title=Forging process of Titanium alloy |publisher=Titanium Info Group |date=2020-07-24}}</ref><ref name="ad1">{{cite news |url=https://www.aubertduval.com/wp-media/uploads/2021/06/brochure-titane_2021.pdf |title=TITANIUM FOR DEMANDING MARKETS from ingots to finished parts |date=June 2021 |publisher=Aubert & Duval}}</ref> and may include [[Friction welding]],<ref name="mti1">{{cite news |url=https://blog.mtiwelding.com/linear-friction-welding-for-titanium-forgings |title=Linear Friction Welding: A Solution for Titanium Forgings }}</ref> [[cryo-forging]],<ref name="mdes1">{{cite news |url=https://www.machinedesign.com/materials/article/21179098/ultra-cold-forging-makes-titanium-strong-and-ductile |title=Ultra-Cold Forging Makes Titanium Strong and Ductile |date=21 October 2021 }}</ref> and [[Vacuum arc remelting]].