What is Austenite?
[[Image:Iron carbon phase diagram.svg|thumb|right|250px|Iron-carbon phase diagram, showing the conditions under which '''austenite''' (γ) is stable in carbon steel.]] [[File:IronAlfa&IronGamma.svg|thumb|Allotropes of iron; alpha iron and gamma iron]] '''Austenite''' is iron but in a metallic form. It is one of the [[allotropes of iron]], which means its physical form is different from iron, but its chemical form is the same.<ref>{{Cite web|url=http://www.dictionary.com/browse/allotrope|title=Dictionary.com|website=Dictionary|access-date=May 18, 2016}}</ref><ref name=Reed-Hill>{{cite book |author=Reed-Hill R, Abbaschian R |title=Physical Metallurgy Principles, 3rd Edition |publisher=PWS-Kent Publishing |location=Boston |year=1991 |isbn=0-534-92173-6 }}</ref> It is named after Sir [[William Chandler Roberts-Austen]] (1843–1902).<ref name=Gove>{{cite book |editor=Gove PB |title=Webster's Seventh New Collegiate Dictionary |publisher=G & C Merriam Company |location=Springfield, Massachusetts, USA |year=1963 |page=58 }}</ref> ==Austenitization== '''Austenitization''' means to heat iron, iron-based metal, or steel to a high temperature. At that temperature, the crystal structure of the metal changes from ferrite to austenite,<ref>{{cite web |author=Nichols R |title=Quenching and tempering of welded carbon steel tubulars |date=Jul 2001 |url=http://www.thefabricator.com/TubePipeFabrication/TubePipeFabrication_Article.cfm?ID=237 }}</ref><ref name=Lambers>{{cite journal |author=Lambers HG, Tschumak S, Maier HJ, Canadinc D |title=Role of Austenitization and Pre-Deformation on the Kinetics of the Isothermal Bainitic Transformation |journal=Metal Mater Trans A. |date=Apr 2009 |doi=10.1007/s11661-009-9827-z |bibcode=2009MMTA..tmp...74L |volume=40 |issue=6 |pages=1355–1366 |s2cid=136882327 }}</ref> which can dissolve more carbon. For some irons, iron-based metals, and steels, the presence of carbides may occur during this austenitization step. The term commonly used for this is '''two-phase austenitization'''.<ref name=smnm>