Editing Inconel

{{Short description|Austenitic nickel-chromium superalloys}}
[[File:Inconel 718.JPG|thumb|Inconel 718 round bar]]

'''Inconel''' is a [[nickel]]-[[chromium]]-based [[superalloy]] often utilized in extreme environments where components are subjected to high temperature, pressure or [[Mechanical load|mechanical loads]]. Inconel alloys are [[oxidation]]- and [[corrosion]]-resistant. When heated, Inconel forms a thick, stable, [[passivation (chemistry)|passivating]] oxide layer protecting the surface from further attack. Inconel retains strength over a wide temperature range, attractive for high-temperature applications where aluminum and steel would succumb to [[creep (deformation)|creep]] as a result of thermally-induced crystal vacancies. Inconel's high-temperature strength is developed by [[solid solution strengthening]] or [[precipitation hardening]], depending on the alloy.<ref name="auto">[http://www.specialmetals.com/documents/Inconel%20alloy%20718.pdf Inconel alloy 718] {{Web archive |url=https://web.archive.org/web/20170517080338/http://www.specialmetals.com/documents/Inconel%20alloy%20718.pdf |date=2017-05-17 }}, Special Metals Corporation</ref><ref name="nickelinstitute.org">{{Cite web |title=Engineering Properties of ALLOY 713C |url=http://www.nickelinstitute.org/~/media/Files/TechnicalLiterature/Alloy713C_337_.ashx |url-status=dead |archive-url=https://web.archive.org/web/20150902002913/http://www.nickelinstitute.org/~/media/Files/TechnicalLiterature/Alloy713C_337_.ashx |archive-date=2015-09-02 |access-date=2015-09-16}}</ref>

Inconel alloys are typically used in high temperature applications. Common trade names for various Inconel alloys include:
* Alloy 625: [[Inconel 625]], Chronin 625, Altemp 625, Sanicro 625, Haynes 625, Nickelvac 625 Nicrofer 6020 and UNS designation N06625.<ref>{{cite web |url= http://www.source1alloys.com/alloys/Inconel_625.html |title= Special Alloys: Inconel 625 |access-date= 2010-04-26 |url-status= dead |archive-url= https://web.archive.org/web/20090605051532/http://source1alloys.com/alloys/Inconel_625.html |archive-date= 2009-06-05 }}</ref> 
* Alloy 600: NA14, BS3076, 2.4816, NiCr15Fe (FR), NiCr15Fe (EU), NiCr15Fe8 (DE) and UNS designation N06600.
* Alloy 718: Nicrofer 5219, Superimphy 718, Haynes 718, Pyromet 718, Supermet 718, Udimet 718 and UNS designation N07718.<ref>{{cite web |url= https://www.americanspecialmetals.com/InconelAlloy718.html |title= Inconel Alloy 718 |access-date= 2023-01-16 }}</ref>

== History ==
The Inconel family of alloys was first developed before December 1932, when its [[trademark]] was registered by the US company [[International Nickel Company]] of Delaware and New York.<ref name="wmi">{{cite news |title=Word Mark : Inconel |url=https://tmsearch.uspto.gov/bin/showfield?f=doc&state=4810:9v10p.5.3 |agency=Trademark Electronic Search System (TESS) |publisher=United States Patent and Trademark Office}}</ref><ref name="min">{{cite book |title=Monel, Inconel, Nickel, and Nickel Alloys |date=1947 |publisher=International Nickel Company |location=Development and Research Division}}</ref> A significant early use was found in support of the development of the [[Frank Whittle|Whittle]] jet engine,<ref name=ehj>{{cite web|last1=Jones|first1=T.L.|title=Frank Whittle's W2B Turbojet: United Kingdom versus United States Development|url=http://www.enginehistory.org/GasTurbines/W2B.shtml|website=EngineHistory.org|publisher=Aircraft Engine Historical Society, Inc|access-date=27 March 2016|url-status=dead|archive-url=https://web.archive.org/web/20160330052504/http://enginehistory.org/GasTurbines/W2B.shtml|archive-date=30 March 2016}}</ref> during the 1940s by research teams at Henry Wiggin & Co of [[Hereford, England]] a subsidiary of the [[Mond Nickel Company]],<ref name="dbs32">{{cite book |title=Annual Report on the Mineral Production of Canada |date=1932 |publisher=Canada. Dominion Bureau of Statistics |page=88}}</ref> which merged with [[Inco]] in 1928. The Hereford Works and its properties including the Inconel trademark were acquired in 1998 by [[Special Metals Corporation]].<ref name=smch>{{cite web|url=http://www.specialmetals.com/history.php |title=Special Metals Corporation: History |access-date=2012-05-18 |url-status=dead |archive-url=https://web.archive.org/web/20080421064350/http://www.specialmetals.com/history.php |archive-date=April 21, 2008 }}</ref>

==Specific data==
{| class="sortable wikitable" style="text-align:right;"
|-
! Alloy
! [[Solidus (chemistry)|Solidus]] °C (°F)
! [[Liquidus]] °C (°F)
|-
|align="left"| Inconel 600<ref>{{cite web |title = NINC30 |department=ASM Material Data Sheet |website=asm.matweb.com |url=http://asm.matweb.com/search/SpecificMaterial.asp?bassnum=NINC30}}</ref>
| 1354 ({{convert|1354|C|F|disp=number}})
| 1413 ({{convert|1413|C|F|disp=number}})
|-
|align="left"| Inconel 617<ref>{{cite web |title = Inconel 617 Alloy |website = American Elements |url=https://www.americanelements.com/inconel-617-alloy}}</ref><ref>{{cite web |title = NINC32 |department=ASM Material Data Sheet |website=asm.matweb.com |url=http://asm.matweb.com/search/SpecificMaterial.asp?bassnum=NINC32}}</ref>
| 1332 ({{convert|1332|C|F|disp=number}})
| 1377 ({{convert|1377|C|F|disp=number}})
|-
|align="left"| Inconel 625<ref>{{cite web |title = Inconel 625 Alloy |website = American Elements |url=https://www.americanelements.com/inconel-625-alloy}}</ref>
| 1290 ({{convert|1290|C|F|disp=number}})
| 1350 ({{convert|1350|C|F|disp=number}})
|-
|align="left"| Inconel 690<ref>{{cite web |title = Inconel 690 Alloy |website = American Elements |url=https://www.americanelements.com/inconel-690-alloy}}</ref>
| 1343 ({{convert|1343|C|F|disp=number}})
| 1377 ({{convert|1377|C|F|disp=number}})
|-
|align="left"| Inconel 718<ref>{{cite web |title = Inconel 718 Alloy |website = American Elements |url=https://www.americanelements.com/inconel-718-alloy}}</ref>
| 1260 ({{convert|1260|C|F|disp=number}})
| 1336 ({{convert|1336|C|F|disp=number}})
|-
|align="left"| Inconel X-750<ref>{{cite web |title = NINC35 |department=ASM Material Data Sheet |website=asm.matweb.com |url=http://asm.matweb.com/search/SpecificMaterial.asp?bassnum=NINC35 }}</ref>
| 1390 ({{convert|1390|C|F|disp=number}})
| 1430 ({{convert|1430|C|F|disp=number}})
|}

==Composition==
Inconel alloys vary widely in their compositions, but all are predominantly nickel, with chromium as the second element.

{| class="wikitable" border="1" style="text-align: center"
|-
! rowspan="2"  | Inconel
! colspan="15" | Element, proportion by mass (%)
|-
! width="6%" | [[Nickel|Ni]]
! width="6%" | [[Chromium|Cr]]
! width="6%" | [[Iron|Fe]]
! width="6%" | [[Molybdenum|Mo]]
! width="6%" | [[Niobium|Nb]] & [[Tantalum|Ta]]
! width="6%" | [[Cobalt|Co]]
! width="6%" | [[Manganese|Mn]]
! width="6%" | [[Copper|Cu]]
! width="6%" | [[Aluminium|Al]]
! width="6%" | [[Titanium|Ti]]
! width="6%" | [[Silicon|Si]]
! width="6%" | [[Carbon|C]]
! width="6%" | [[Sulfur|S]]
! width="6%" | [[Phosphorus|P]]
! width="6%" | [[Boron|B]]
|-
| 600<ref>[http://www.specialmetals.com/assets/smc/documents/alloys/inconel/inconel-alloy-600.pdf Inconel alloy 600] {{Webarchive|url=https://web.archive.org/web/20210127104028/https://www.specialmetals.com/assets/smc/documents/alloys/inconel/inconel-alloy-600.pdf |date=2021-01-27 }}, Special Metals Corporation</ref>
| ≥72.0{{efn|Includes [[cobalt]]}}
| 14.0–17.0
| 6.0–10.0
|
|
| {{n/a}}
| ≤1.0
| ≤0.5
|
|
| ≤0.5
| ≤0.15
| ≤0.015
|
|
|-
| 617<ref>[http://www.hightempmetals.com/techdata/hitempInconel617data.php hightempmetals.com], High Temp Metals</ref>
| 44.2–61.0
| 20.0–24.0
| ≤3.0
| 8.0–10.0
|
| 10.0–15.0
| ≤0.5
| ≤0.5
| 0.8–1.5
| ≤0.6
| ≤0.5
| 0.05–0.15
| ≤0.015
| ≤0.015
| ≤0.006

|-
| [[Inconel 625|625]]<ref>[https://wayback.archive-it.org/all/20090226220715/http://www.specialmetals.com/documents/Inconel%20alloy%20625.pdf Inconel alloy 625], Special Metals Corporation</ref>
| ≥58.0
| 20.0–23.0
| ≤5.0
| 8.0–10.0
| 3.15–4.15
| ≤1.0
| ≤0.5
|
| ≤0.4
| ≤0.4
| ≤0.5
| ≤0.1
| ≤0.015
| ≤0.015
|
|-
| 690<ref name=690pdf>[http://www.specialmetals.com/assets/smc/documents/alloys/inconel/inconel-alloy-690.pdf Inconel alloy 690] {{Webarchive|url=https://web.archive.org/web/20210127102230/https://www.specialmetals.com/assets/smc/documents/alloys/inconel/inconel-alloy-690.pdf |date=2021-01-27 }}, Special Metals Corporation</ref>
| ≥58
| 27–31
| 7–11
|
|
|
| ≤0.50
| ≤0.50
|
|
| ≤0.50
| ≤0.05
| ≤0.015
|
|
|-
| Nuclear grade 690<ref name=690pdf/>
| ≥58
| 28–31
| 7–11
|
|
| ≤0.10
| ≤0.50
| ≤0.50
|
|
| ≤0.50
| ≤0.04
| ≤0.015
|
|
|-
| 718<ref name="auto"/>
| 50.0–55.0
| 17.0–21.0
| {{n/a|Balance}}
| 2.8–3.3
| 4.75–5.5
| ≤1.0
| ≤0.35
| ≤0.3
| 0.2–0.8
| 0.65–1.15
| ≤0.35
| ≤0.08
| ≤0.015
| ≤0.015
| ≤0.006

|-
| X-750<ref>[http://www.specialmetals.com/assets/smc/documents/alloys/inconel/inconel-alloy-x-750.pdf Inconel alloy X-750] {{Webarchive|url=https://web.archive.org/web/20210125144346/https://www.specialmetals.com/assets/smc/documents/alloys/inconel/inconel-alloy-x-750.pdf |date=2021-01-25 }}, Special Metals Corporation</ref>
| ≥70.0
| 14.0–17.0
| 5.0–9.0
|
| 0.7–1.2
| ≤1.0
| ≤1.0
| ≤0.5
| 0.4–1.0
| 2.25–2.75
| ≤0.5
| ≤0.08
| ≤0.01
|
|
|}
{{notelist}}

==Properties==
When heated, Inconel forms a thick and stable [[Passivation (chemistry)|passivating]] oxide layer protecting the surface from further attack. Inconel retains strength over a wide temperature range, attractive for high-temperature applications where [[aluminium]] and [[steel]] would succumb to [[Creep (deformation)|creep]] as a result of thermally induced crystal vacancies (see [[Arrhenius equation]]). Inconel's high temperature strength is developed by [[solid solution strengthening]] or [[precipitation strengthening]], depending on the alloy. In [[age hardening|age-hardening]] or precipitation-strengthening varieties, small amounts of [[niobium]] combine with [[nickel]] to form the [[intermetallic]] compound Ni<sub>3</sub>Nb or [[Superalloy#Families of superalloys|gamma double prime]] (γ″). Gamma prime forms small cubic crystals that inhibit [[Slip (materials science)|slip]] and creep effectively at elevated temperatures. The formation of gamma-prime crystals increases over time, especially after three hours of a heat exposure of  {{Convert|850|C|F}}, and continues to grow after 72 hours of exposure.<ref>{{cite web|url=http://www.doitpoms.ac.uk/miclib/full_record.php?id=716|title=DoITPoMS - Full Record|website=www.doitpoms.ac.uk}}</ref>

== Strengthening mechanisms ==
The most prevalent hardening mechanisms for Inconel alloys are [[Precipitation hardening|precipitate strengthening]] and [[solid solution strengthening]]. In Inconel alloys, one of the two often dominates. For alloys like Inconel 718, precipitate strengthening is the main strengthening mechanism. The majority of strengthening comes from the presence of gamma double prime (γ″) precipitates.<ref name="Mignanelli-2017">{{Cite journal |last1=Mignanelli |first1=P. M. |last2=Jones |first2=N. G. |last3=Pickering |first3=E. J. |last4=Messé |first4=O. M. D. M. |last5=Rae |first5=C. M. F. |last6=Hardy |first6=M. C. |last7=Stone |first7=H. J. |date=2017-07-15 |title=Gamma-gamma prime-gamma double prime dual-superlattice superalloys |journal=Scripta Materialia |language=en |volume=136 |pages=136–140 |doi=10.1016/j.scriptamat.2017.04.029 |issn=1359-6462|doi-access=free }}</ref><ref name="Devaux-2008">{{Cite journal |last1=Devaux |first1=A. |last2=Nazé |first2=L. |last3=Molins |first3=R. |last4=Pineau |first4=A. |last5=Organista |first5=A. |last6=Guédou |first6=J. Y. |last7=Uginet |first7=J. F. |last8=Héritier |first8=P. |date=2008-07-15 |title=Gamma double prime precipitation kinetic in Alloy 718 |url=https://www.sciencedirect.com/science/article/pii/S0921509307016073 |journal=Materials Science and Engineering: A |language=en |volume=486 |issue=1 |pages=117–122 |doi=10.1016/j.msea.2007.08.046 |issn=0921-5093|url-access=subscription }}</ref><ref name="Hosseini-2019">{{Cite journal |last1=Hosseini |first1=E. |last2=Popovich |first2=V. A. |date=2019-12-01 |title=A review of mechanical properties of additively manufactured Inconel 718 |url=https://www.sciencedirect.com/science/article/pii/S221486041930226X |journal=Additive Manufacturing |language=en |volume=30 |pages=100877 |doi=10.1016/j.addma.2019.100877 |issn=2214-8604|url-access=subscription }}</ref><ref name="Shankar-2001">{{Cite journal |last1=Shankar |first1=Vani |last2=Bhanu Sankara Rao |first2=K |last3=Mannan |first3=S. L |date=2001-02-01 |title=Microstructure and mechanical properties of Inconel 625 superalloy |url=https://www.sciencedirect.com/science/article/pii/S0022311500007236 |journal=Journal of Nuclear Materials |language=en |volume=288 |issue=2 |pages=222–232 |doi=10.1016/S0022-3115(00)00723-6 |bibcode=2001JNuM..288..222S |issn=0022-3115|url-access=subscription }}</ref> Inconel alloys have a γ matrix phase with an [[Face Centered Cubic | FCC]] structure.<ref name="Hosseini-2019" /><ref name="Tucho-2017">{{Cite journal |last1=Tucho |first1=Wakshum M. |last2=Cuvillier |first2=Priscille |last3=Sjolyst-Kverneland |first3=Atle |last4=Hansen |first4=Vidar |date=2017-03-24 |title=Microstructure and hardness studies of Inconel 718 manufactured by selective laser melting before and after solution heat treatment |url=https://www.sciencedirect.com/science/article/pii/S092150931730223X |journal=Materials Science and Engineering: A |language=en |volume=689 |pages=220–232 |doi=10.1016/j.msea.2017.02.062 |issn=0921-5093|url-access=subscription }}</ref><ref name="Yu-2021">{{Cite journal |last1=Yu |first1=Xiaobin |last2=Lin |first2=Xin |last3=Tan |first3=Hua |last4=Hu |first4=Yunlong |last5=Zhang |first5=Shuya |last6=Liu |first6=Fencheng |last7=Yang |first7=Haiou |last8=Huang |first8=Weidong |date=2021-02-01 |title=Microstructure and fatigue crack growth behavior of Inconel 718 superalloy manufactured by laser directed energy deposition |url=https://www.sciencedirect.com/science/article/pii/S0142112320305375 |journal=International Journal of Fatigue |language=en |volume=143 |pages=106005 |doi=10.1016/j.ijfatigue.2020.106005 |issn=0142-1123|url-access=subscription }}</ref><ref name="Jambor-2017">{{Cite journal |last1=Jambor |first1=Michal |last2=Bokůvka |first2=Otakar |last3=Nový |first3=František |last4=Trško |first4=Libor |last5=Belan |first5=Juraj |date=2017-06-01 |title=Phase Transformations in Nickel base Superalloy Inconel 718 during Cyclic Loading at High Temperature |journal=Production Engineering Archives |language=en |volume=15 |issue=15 |pages=15–18 |doi=10.30657/pea.2017.15.04|doi-access=free }}</ref> γ″ precipitates are made of Ni and Nb, specifically with a Ni<sub>3</sub>Nb composition. These precipitates are fine, coherent, disk-shaped, intermetallic particles with a tetragonal structure.<ref name="Devaux-2008" /><ref name="Hosseini-2019" /><ref name="Shankar-2001" /><ref name="Tucho-2017" /><ref name="Bennett-2021">{{Cite journal |last1=Bennett |first1=Jennifer |last2=Glerum |first2=Jennifer |last3=Cao |first3=Jian |date=2021-01-01 |title=Relating additively manufactured part tensile properties to thermal metrics |url=https://www.sciencedirect.com/science/article/pii/S0007850621000779 |journal=CIRP Annals |language=en |volume=70 |issue=1 |pages=187–190 |doi=10.1016/j.cirp.2021.04.053 |issn=0007-8506|url-access=subscription }}</ref><ref name="Li-2020">{{Cite journal |last1=Li |first1=Zuo |last2=Chen |first2=Jing |last3=Sui |first3=Shang |last4=Zhong |first4=Chongliang |last5=Lu |first5=Xufei |last6=Lin |first6=Xin |date=2020-01-01 |title=The microstructure evolution and tensile properties of Inconel 718 fabricated by high-deposition-rate laser directed energy deposition |url=https://www.sciencedirect.com/science/article/pii/S2214860419308450 |journal=Additive Manufacturing |language=en |volume=31 |pages=100941 |doi=10.1016/j.addma.2019.100941 |issn=2214-8604|url-access=subscription }}</ref><ref name="Glerum-2021">{{Cite journal |last1=Glerum |first1=Jennifer |last2=Bennett |first2=Jennifer |last3=Ehmann |first3=Kornel |last4=Cao |first4=Jian |date=2021-05-01 |title=Mechanical properties of hybrid additively manufactured Inconel 718 parts created via thermal control after secondary treatment processes |url=https://www.sciencedirect.com/science/article/pii/S0924013621000078 |journal=Journal of Materials Processing Technology |language=en |volume=291 |pages=117047 |doi=10.1016/j.jmatprotec.2021.117047 |issn=0924-0136|url-access=subscription }}</ref><ref name="Deng-2018">{{Cite journal |last1=Deng |first1=Dunyong |last2=Peng |first2=Ru Lin |last3=Brodin |first3=Håkan |last4=Moverare |first4=Johan |date=2018-01-24 |title=Microstructure and mechanical properties of Inconel 718 produced by selective laser melting: Sample orientation dependence and effects of post heat treatments |url=https://www.sciencedirect.com/science/article/pii/S0921509317316416 |journal=Materials Science and Engineering: A |language=en |volume=713 |pages=294–306 |doi=10.1016/j.msea.2017.12.043 |issn=0921-5093|url-access=subscription }}</ref>

Secondary precipitate strengthening comes from gamma prime (γ') precipitates. The γ' phase can appear in multiple compositions such as Ni<sub>3</sub>(Al, Ti).<ref name="Devaux-2008" /><ref name="Hosseini-2019" /><ref name="Shankar-2001" /> The precipitate phase is coherent and has an FCC structure, like the γ matrix;<ref name="Deng-2018" /><ref name="Tucho-2017" /><ref name="Bennett-2021" /><ref name="Li-2020" /><ref name="Glerum-2021" /> The γ' phase is much less prevalent than γ″. The volume fraction of the γ″ and γ' phases are approximately 15% and 4% after precipitation, respectively.<ref name="Devaux-2008" /><ref name="Hosseini-2019" /> Because of the coherency between the γ matrix and the γ' and γ″ precipitates, strain fields exist that obstruct the motion of dislocations. The prevalence of carbides with MX(Nb, Ti)(C, N) compositions also helps to strengthen the material.<ref name="Hosseini-2019" /> For precipitate strengthening, elements like niobium, titanium, and tantalum play a crucial role.<ref name="Aeether">{{Cite web |author=Aeether Co Limited |title=What is Solid Solution? Why do Nickel Alloy / Superalloy need Solution Treatment? |url=https://www.aeether.com/AEETHER/media/media-29/media.html |access-date=2023-05-08 |website=aeether.com |language=en}}</ref> 

Because the γ″ phase is metastable, over-aging can result in the transformation of γ″ phase precipitates to delta (δ) phase precipitates, their stable counterparts.<ref name="Hosseini-2019" /><ref name="Tucho-2017" /> The δ phase has an orthorhombic structure, a Ni<sub>3</sub>(Nb, Mo, Ti) composition, and is incoherent.<ref>{{Cite journal |last1=Wang |first1=Yachao |last2=Shi |first2=Jing |date=2019-12-01 |title=Microstructure and Properties of Inconel 718 Fabricated by Directed Energy Deposition with In-Situ Ultrasonic Impact Peening |url=https://doi.org/10.1007/s11663-019-01672-3 |journal=Metallurgical and Materials Transactions B |language=en |volume=50 |issue=6 |pages=2815–2827 |doi=10.1007/s11663-019-01672-3 |bibcode=2019MMTB...50.2815W |issn=1543-1916|url-access=subscription }}</ref><ref name="Jambor-2017" /> As a result, the transformation of γ″ to δ in Inconel alloys leads to the loss of coherency strengthening, making for a weaker material. That being said,  in appropriate quantities, the δ phase is responsible for [[Grain boundary strengthening|grain boundary pinning]] and strengthening.<ref name="Deng-2018" /><ref name="Glerum-2021" /><ref name="Jambor-2017" />

Another common phase in Inconel alloys is the Laves intermetallic phase. Its compositions are (Ni, Cr, Fe)<sub>x</sub>(Nb, Mo, Ti)<sub>y</sub> and Ni<sub>y</sub>Nb, it is brittle, and its presence can be detrimental to the mechanical behavior of Inconel alloys.<ref name="Tucho-2017" /><ref name="Deng-2018" /><ref name="Sohrabi-2018">{{Cite journal |last1=Sohrabi |first1=Mohammad Javad |last2=Mirzadeh |first2=Hamed |last3=Rafiei |first3=Mohsen |date=2018-08-01 |title=Solidification behavior and Laves phase dissolution during homogenization heat treatment of Inconel 718 superalloy |url=https://www.sciencedirect.com/science/article/pii/S0042207X18305700 |journal=Vacuum |language=en |volume=154 |pages=235–243 |doi=10.1016/j.vacuum.2018.05.019 |bibcode=2018Vacuu.154..235S |issn=0042-207X|url-access=subscription }}</ref> Sites with large amounts of Laves phase are prone to crack propagation because of their higher potential for stress concentration.<ref name="Li-2020" /> Additionally, due to its high Nb, Mo, and Ti content, the Laves phase can exhaust the matrix of these elements, ultimately making precipitate and solid-solution strengthening more difficult.<ref name="Glerum-2021" /><ref name="Sohrabi-2018" /><ref name="Yu-2021" /> 

For alloys like Inconel 625, solid-solution hardening is the main strengthening mechanism. Elements like Mo {{clarification needed | date= July 2024}} are important in this process. Nb and Ta can also contribute to solid solution strengthening to a lesser extent.<ref name="Aeether" /> In solid solution strengthening, Mo atoms are substituted into the γ matrix of Inconel alloys. Because Mo atoms have a significantly larger radius than those of Ni (209 pm and 163 pm, respectively), the substitution creates strain fields in the crystal lattice, which hinder the motion of dislocations, ultimately strengthening the material. 

The combination of elemental composition and strengthening mechanisms is why Inconel alloys can maintain their favorable mechanical and physical properties, such as high strength and fatigue resistance, at elevated temperatures, specifically those up to 650°C.<ref name="Mignanelli-2017" />

==Machining==
Inconel is a difficult metal to shape and to machine using traditional [[cold forming]] techniques due to rapid [[work hardening]]. After the first machining pass, work hardening tends to plastically deform either the workpiece or the tool on subsequent passes. For this reason, age-hardened Inconels such as 718 are typically machined using an aggressive but slow cut with a hard tool, minimizing the number of passes required. Alternatively, the majority of the machining can be performed with the workpiece in a "solutionized" form,{{clarification needed|date=September 2022}} with only the final steps being performed after age hardening. However some claim{{who|date=September 2022}} that Inconel can be machined extremely quickly with very fast spindle speeds using a multifluted ceramic tool with small width of cut at high feed rates as this causes localized heating and softening in front of the flute.

External [[screw thread|threads]] are machined using a [[lathe]] to "single-point" the threads or by rolling the threads in the solution treated condition (for hardenable alloys) using a [[screw machine (automatic lathe)|screw machine]]. Inconel 718 can also be roll-threaded after full aging by using [[induction heat]] to  {{Convert|700|C|-1}} without increasing the grain size.{{Citation needed|date=January 2010}} Holes with internal threads are made by threadmilling. Internal threads can also be formed using a sinker [[electrical discharge machining]] (EDM).{{citation needed|date=August 2013}}

==Joining==
Welding of some Inconel alloys (especially the gamma prime precipitation hardened family; e.g., [[Waspaloy]] and X-750) can be difficult due to cracking and microstructural segregation of alloying elements in the [[heat-affected zone]]. However, several alloys such as 625 and 718 have been designed to overcome these problems. The most common welding methods are [[gas tungsten arc welding]] and [[electron-beam welding]].<ref>{{Citation | title = Joining | url = http://www.specialmetalswelding.com/publica/joining.pdf | access-date = 2009-10-09}}.</ref>

==Uses==
[[File:Astra_Rocket_Engine_—_Delphin_3.0.jpg|thumb|Delphin 3.0 rocket engine, used on [[Astra Rocket]]. 3D-printed in Inconel]]
Inconel is often used in extreme environments. It is common in [[gas turbine]] blades, seals, and combustors, as well as [[turbocharger]] rotors and seals, electric submersible well pump motor shafts, high temperature fasteners, chemical processing and [[pressure vessel]]s, [[heat exchanger]] tubing, steam generators and core components in nuclear [[pressurized water reactors]],<ref>{{cite web|url=http://www.specialmetals.com/documents/Inconel%20alloy%20625.pdf|archive-url=https://wayback.archive-it.org/all/20090226220715/http://www.specialmetals.com/documents/Inconel%20alloy%20625.pdf|url-status=dead|archive-date=2009-02-26|title=''Inconel alloy 625'', Specials Metals, 2015}}</ref> [[natural gas processing]] with contaminants such as H<sub>2</sub>S and CO<sub>2</sub>, [[firearm]] [[suppressor|sound suppressor]] blast baffles, and [[Formula One racing|Formula One]], [[NASCAR]], [[National Hot Rod Association|NHRA]], and [[Audi Performance and Racing|APR, LLC]] exhaust systems.<ref>[http://www.specialmetals.com/power.php Power Generation] {{webarchive|url=https://archive.today/20120914045808/http://www.specialmetals.com/power.php |date=2012-09-14 }}, Special Metals Corporation.</ref><ref>[http://www.specialmetals.com/chemical.php Chemical Processing] {{webarchive|url=https://archive.today/20130202213225/http://www.specialmetals.com/chemical.php |date=2013-02-02 }}, Special Metals Corporation.</ref> It is also used in the turbo system of the 3rd generation [[Mazda RX7]], and the exhaust systems of high powered [[Wankel engine]] and [[Norton_Motorcycle_Company#Wankel_engine|Norton motorcycles]] where exhaust temperatures reach more than {{Convert|1000|C|F}}.<ref>Motorcycle Trader.Norton Rotary Revival.Cathcart.Dec 2007.</ref> Inconel is increasingly used in the boilers of waste [[incineration|incinerators]].<ref>[http://www.volund.dk/content/download/531/2353/file/Inconel_eng_pdf.pdf Inconell – state-of-the-art corrosion protection] {{webarchive|url=https://web.archive.org/web/20081115001718/http://www.volund.dk/content/download/531/2353/file/Inconel_eng_pdf.pdf |date=2008-11-15 }} by Babcock & Wilcox Vølund, 2003</ref> The [[Joint European Torus]] and [[DIII-D (tokamak)|DIII-D]] tokamaks' vacuum vessels are made of Inconel.<ref>[http://www.jet.efda.org/multimedia/photo-gallery/picture-of-the-week/?pid=268 The Inconel JET vessel in use since 1983] {{webarchive|url=https://web.archive.org/web/20100227001825/http://www.jet.efda.org/multimedia/photo-gallery/picture-of-the-week/?pid=268 |date=2010-02-27 }}. A simple, sturdy structure.</ref> Inconel 718 is commonly used for [[cryogenic]] storage tanks, downhole shafts, wellhead parts,<ref>[https://www.inconel718.in/ Inconel Alloy], Inconel 718.</ref> and in the aerospace industry -- where  it has become a prime candidate material for constructing heat resistant turbines.<ref>{{Cite web |title=What are the applications for Inconel 718? |url=https://www.langleyalloys.com/knowledge-advice/what-are-the-applications-for-inconel-718/ |access-date=2022-03-23 |website=Langley Alloys |language=en-US}}</ref>

===Aerospace===
* The [[Space Shuttle]] used four Inconel studs to secure the solid rocket boosters to the launch platform, eight total studs supported the entire weight of the ready to fly Shuttle system. Eight [[frangible nut]]s are encased on the outside of the solid rocket boosters, at launch explosives separated the nuts releasing the Shuttle from its launch platform.{{citation needed|date=February 2017}}
* [[North American Aviation]] constructed the skin of the [[North American X-15]] [[rocket-powered aircraft]] out of Inconel X/750 alloy.<ref>Robert S. Houston, Richard P. Hallion, and Ronald G. Boston, [http://www.hq.nasa.gov/office/pao/History/hyperrev-x15/ch-0.html Editor's introduction, "Transiting from Air to Space: The North American X-15"] {{Webarchive|url=https://web.archive.org/web/20070810061825/http://www.hq.nasa.gov/office/pao/History/hyperrev-x15/ch-0.html |date=2007-08-10 }}, ''The Hypersonic Revolution: Case Studies in the History of Hypersonic Technology'', Air Force History and Museums Program, 1998. NASA.gov.</ref>
* [[Rocketdyne]] used Inconel X-750 for the thrust chamber of the [[F-1 (rocket engine)|F-1 rocket engine]] used in the first stage of the [[Saturn V]] booster.<ref>Anthony Young, "The Saturn V Booster: Powering Apollo into History", Springer-Verlag, 2009.</ref>
* [[SpaceX]] uses Inconel (Inconel 718<ref>{{Cite web |url=https://metalpress.onlinemetals.com/inconel-uses/ |title=''History of inconel and superalloys'' |access-date=2020-10-24 |archive-date=2020-08-09 |archive-url=https://web.archive.org/web/20200809090854/https://metalpress.onlinemetals.com/inconel-uses/ |url-status=dead }}</ref>) in the engine manifold of their [[SpaceX Merlin|Merlin]] engine which powers the [[Falcon 9]] [[launch vehicle]].<ref name=slr20130813>{{cite web |title=Space Launch Report: SpaceX Falcon 9 Data Sheet |url=http://www.spacelaunchreport.com/falcon9.html |archive-url=https://web.archive.org/web/20220406013726/http://www.spacelaunchreport.com/falcon9.html |archive-date=6 Apr 2022 |date=1 May 2017 |url-status=dead}}</ref>
* In a first for [[3D-printer|3D printing]], the SpaceX [[SuperDraco]] [[rocket engine]] that provides [[launch escape system]] for the [[Dragon V2]] crew-carrying [[space capsule]] is fully printed. In particular, the engine combustion chamber is printed of Inconel using a process of [[direct metal laser sintering]], and operates at very high temperature and a [[chamber pressure]] of {{convert|1000|psi|MPa|disp=flip}}.<ref name=ludiInco/><ref name=aw20140530>{{cite news |last=Norris |first=Guy |title=SpaceX Unveils 'Step Change' Dragon 'V2' |url=http://aviationweek.com/space/spacex-unveils-step-change-dragon-v2 |access-date=2014-05-30 |newspaper=Aviation Week |date=2014-05-30 |archive-date=2014-05-31 |archive-url=https://web.archive.org/web/20140531110355/http://aviationweek.com/space/spacex-unveils-step-change-dragon-v2 |url-status=dead }}</ref><ref name=sdc20140529>{{cite news |last=Kramer|first=Miriam |title=SpaceX Unveils Dragon V2 Spaceship, a Manned Space Taxi for Astronauts — Meet Dragon V2: SpaceX's Manned Space Taxi for Astronaut Trips |url=http://www.space.com/26063-spacex-unveils-dragon-v2-manned-spaceship.html |access-date=2014-05-30 |newspaper=space.com |date=2014-05-30 }}</ref><ref name=nsf20140530>
{{cite news |last=Bergin|first=Chris |title=SpaceX lifts the lid on the Dragon V2 crew spacecraft |url=http://www.nasaspaceflight.com/2014/05/spacex-lifts-the-lid-dragon-v2-crew-spacecraft/ |access-date=2015-03-06 |newspaper=NASAspaceflight.com |date=2014-05-30 }}</ref><ref name=nsj20140530>{{cite news |last=Foust|first=Jeff |url=http://www.newspacejournal.com/2014/05/30/spacex-unveils-its-21st-century-spaceship/|title=SpaceX unveils its "21st century spaceship" |access-date=2015-03-06 |newspaper=NewSpace Journal |date=2014-05-30}}</ref><ref name=sx20140801>{{cite web |title=SpaceX Launches 3D-Printed Part to Space, Creates Printed Engine Chamber for Crewed Spaceflight |url=http://www.spacex.com/news/2014/07/31/spacex-launches-3d-printed-part-space-creates-printed-engine-chamber-crewed |publisher=SpaceX |access-date=2015-03-06 |quote=''Compared with a traditionally cast part, a printed [part] has superior strength, ductility, and fracture resistance, with a lower variability in materials properties. ... The chamber is regeneratively cooled and printed in Inconel, a high performance superalloy. Printing the chamber resulted in an order of magnitude reduction in lead-time compared with traditional machining – the path from the initial concept to the first hotfire was just over three months. During the hotfire test, ... the SuperDraco engine was fired in both a launch escape profile and a landing burn profile, successfully throttling between 20% and 100% thrust levels. To date the chamber has been fired more than 80 times, with more than 300 seconds of hot fire.'' |archive-date=2017-08-25 |archive-url=https://web.archive.org/web/20170825191053/http://www.spacex.com/news/2014/07/31/spacex-launches-3d-printed-part-space-creates-printed-engine-chamber-crewed |url-status=dead }}</ref><!-- this source also has an excellent-quality photo of the printed SuperDraco rocket engine combustion chamber, but I am unsure how Fair Use works and whether it might be possible to use the image on Wikipedia. -->
* SpaceX cast the [[Raptor (SpaceX)|Raptor]] rocket engine manifolds from SX300, later SX500, which are nickel superalloys (improvement over older Inconel alloys).<ref name=NBF-Raptor>[https://www.nextbigfuture.com/2019/02/spacex-casting-raptor-engine-parts-from-supersteel-alloys.html ''SpaceX Casting Raptor Engine Parts from Supersteel Alloys'' Feb 2019]</ref>

===Automotive===
* [[Tesla, Inc.|Tesla]] claims to use Inconel in place of steel in the main battery pack contactor of its [[Tesla Model S|Model S]] so that it remains springy under the heat of heavy current. Tesla claims that this allows these upgraded vehicles to safely increase the maximum pack output from 1300 to 1500 [[ampere]]s, allowing for an increase in power output (acceleration) Tesla refers to as "[[Ludicrous Mode]]".<ref name=ludiInco>{{cite web|url=http://electrek.co/2015/07/22/elon-musks-recent-ludicrous-announcement-hints-at-more-synergy-between-tesla-and-spacex/ |title=Elon Musk's recent "Ludicrous" announcement hints at more synergy between Tesla and SpaceX - Electrek|work=Electrek |archive-url=https://web.archive.org/web/20150912040737/http://electrek.co/2015/07/22/elon-musks-recent-ludicrous-announcement-hints-at-more-synergy-between-tesla-and-spacex/ |archive-date=12 September 2015 |url-status=live}}</ref><ref>{{cite web|url=http://www.teslamotors.com/blog/three-dog-day|title=Three Dog Day|website=www.teslamotors.com}}</ref>
* [[Ford Motor Company]] is using Inconel to make the turbine wheel in the turbocharger of its [[EcoBlue]] diesel engines introduced in 2016.<ref>{{cite news |title=New Ford EcoBlue turbodiesel engine debuts amid diesel woes |date=April 26, 2016 |publisher=Autoblog.com |url=http://www.autoblog.com/2016/04/26/ford-ecoblue-turbodiesel-engine-transit-van/}}</ref>
* The exhaust [[Poppet valve|valves]] on NHRA Top Fuel and Funny Car drag racing engines are often made of Inconel.<ref>{{cite web |url=https://www.nhra.com/news/2020/piping-power-how-choose-best-headers-your-combination |title=Piping for Power: How to choose the best headers for your combination |first=Evan |last=J. Smith|date=2020-03-22 |access-date=2022-08-09 |work=[[NHRA]]}}</ref>
* [[Ford Australia]] used Inconel valves in their turbocharged [[Ford Barra engine|Barra]] engines. These valves have been proven very reliable, holding in excess of 1900 horsepower.<ref>{{cite web |url=https://www.youtube.com/watch?v=2hKpRTrGT54 |archive-url=https://ghostarchive.org/varchive/youtube/20211212/2hKpRTrGT54 |archive-date=2021-12-12 |url-status=live |title=Inside a 7-second Ford Barra street car <nowiki>|</nowiki> fullBOOST |website=YouTube |date=2021-05-09}}{{cbignore}}</ref>
* [[BMW]] has since used Inconel in the exhaust manifold of its high performance luxury car, the BMW M5 E34 with the S38 engine, withstanding higher temperatures and reducing backpressure.<ref>{{cite journal |first1=Abhinav |last1=Shard |author2=Deepshikha |first3=Vishal |last3=Gupta |first4=M P |last4=Garg |title=The Comprehensive Review on machining of Inconel 718 |journal=[[Journal of Physics: Conference Series |IOP Conference Series: Materials Science and Engineering]] |date=2021 |volume=1033 |issue=1 |page=012069 |doi=10.1088/1757-899X/1033/1/012069 |bibcode=2021MS&E.1033a2069S |s2cid=234133836 |doi-access=free}}</ref>
* [[Jaguar Cars]] has fit, in their [[Jaguar F-Type]] SVR high performance sports car, a new lightweight Inconel titanium exhaust system as standard which withstands higher peak temperatures, reduces backpressure and eliminates {{convert|16|kg|abbr=on}} of mass from the vehicle.<ref>{{cite web|url=http://www.jaguarusa.com/about-jaguar/news/jaguar-introduces-f-type-svr-ahead-of-geneva-debut.html|title=Jaguar Introduces Ultra-High Performance F-Type SVR ahead of Geneva Debut|website=www.jaguarusa.com|access-date=2016-06-29|archive-date=2016-05-09|archive-url=https://web.archive.org/web/20160509140958/http://www.jaguarusa.com/about-jaguar/news/jaguar-introduces-f-type-svr-ahead-of-geneva-debut.html|url-status=dead}}</ref>
* [[DeLorean Motor Company (Texas)|DeLorean Motor Company]] offers Inconel replacements for failure prone OE trailing arm bolts on the [[DMC DeLorean|DMC-12]]. Failure of these bolts can result in loss of the vehicle.<ref>{{cite web|url=http://support.delorean.com/kb/a72/trailing-arm-bolts.aspx|title=Trailing Arm Bolts|website=www.delorean.com}}</ref>

Rolled Inconel was frequently used as the recording medium by engraving in [[flight recorder|black box]] recorders on aircraft.<ref>{{cite web|url=https://gizmodo.com/5729507/the-secret-sauce-of-airplanes-black-box|title=The Secret Sauce of an Airplane's Black Box|first=Brian|last=Barrett|date=10 January 2011 }}</ref>

Alternatives to the use of Inconel in chemical applications such as scrubbers, columns, reactors, and pipes are [[Hastelloy]], [[perfluoroalkoxy]] (PFA) lined carbon steel or [[fiber reinforced plastic]].

==Inconel alloys==
[[Alloy]]s of Inconel include:
* Inconel 188: Readily fabricated for commercial gas turbine and aerospace applications. 
* Inconel 230: Alloy 230 Plate & Sheet mainly used by the power, aerospace, chemical processing and industrial heating industries.
* Inconel 600: In terms of high-temperature and corrosion resistance, Inconel 600 excels.<ref>{{Cite web |author=thepipingmart |date=2023-06-28 |title=Inconel 600 Plates vs Inconel 625 Plates: Which One Should You Choose? |url=https://steemit.com/inconel/@thepipingmart/inconel-600-plates-vs-inconel-625-plates-which-one-should-you-choose |access-date=2023-07-14 |website=Steemit |language=en}}</ref>
* Inconel 601
* Inconel 617: Solid solution strengthened (nickel-chromium-cobalt-molybdenum), high-temperature strength, corrosion and oxidation resistant, high workability and weldability.<ref>{{cite web |date=March 2005 |title=Inconel alloy 617 |url=https://www.specialmetals.com/documents/technical-bulletins/inconel/inconel-alloy-617.pdf |access-date=14 July 2022}}</ref> Incorporated in [[ASME Boiler and Pressure Vessel Code]] for high temperature nuclear applications such as [[molten salt reactor]]s {{circa}} April, 2020.<ref>{{cite web|title=Commercial alloy qualified for new use, expanding nuclear operating temperature|publisher=U.S. Department of Energy [[Idaho National Laboratory]]|date=April 28, 2020|url=https://inl.gov/article/a-new-material-expands-nuclear-operating-temperature/}}</ref>
* [[Inconel 625]]: Acid resistant, good weldability.<ref>{{cite web |url=https://www.refractorymetal.org/inconel-625/ |title=Inconel 625 |website=Advanced Refractory Metal |access-date=Aug 11, 2024}}</ref> The LCF version is typically used in [[bellows]]. It is commonly used for applications in [[aeronautic]], aerospace, marine, chemical and petrochemical industries.<ref>{{cite journal |last1=Oliveira |first1=Mauro |last2=Couto |first2=Antonio |year=2019 |title=Mechanical Behavior of Inconel 625 at Elevated Temperatures |journal=Metals |volume=9 |issue=3 |page=301 |doi=10.3390/met9030301 |doi-access=free}}</ref> It is also used for reactor-core and control-rod components in pressurized water reactors and as heat exchanger tubes in ammonia cracker plants for heavy water production.<ref>{{cite journal |last1=Shankar |first1=Vani |last2=Rao |first2=K.B. |year=2001 |title=Microstructure and mechanical properties of Inconel 625 superalloy |journal=Journal of Nuclear Materials |volume=288 |issue=2-3 |pages=222-232 |doi=10.1016/S0022-3115(00)00723-6}}</ref>
* Inconel 690: Low cobalt content for nuclear applications, and low resistivity<ref>[http://www.ndt-ed.org/GeneralResources/MaterialProperties/ET/Conductivity_Iron.pdf Inconel alloy 690] {{Webarchive|url=https://web.archive.org/web/20131112040149/http://www.ndt-ed.org/GeneralResources/MaterialProperties/ET/Conductivity_Iron.pdf |date=2013-11-12 }}, NDT Resource Center</ref>
* Inconel 706
* Inconel 713C: Precipitation hardenable nickel-chromium base cast alloy<ref name="nickelinstitute.org" />
* Inconel 718: Gamma double prime strengthened with good weldability<ref>{{cite web|url=http://gpiprototype.com/blog/dmls-in-aluminum-inconel-or-titanium-is-it-worth-it.html|title=DMLS in Aluminum, Inconel or Titanium - Is it worth it? - Blog|website=gpiprototype.com}}</ref>
* Inconel 738
* Inconel X-750: Commonly used for gas turbine components, including blades, seals and rotors. 
* Inconel 751: Increased aluminum content for improved rupture strength in the 1600&nbsp;°F range<ref>[https://wayback.archive-it.org/all/20090226220711/http://www.specialmetals.com/documents/Inconel%20alloy%20751.pdf Inconel alloy 751], Special Metals Corporation</ref>
* Inconel 792: Increased aluminum content for improved high temperature corrosion resistant properties, used especially in gas turbines
* Inconel 907
* Inconel 909
* Inconel 925: Inconel 925 is a nonstabilized austenitic stainless steel with low carbon content.<ref>[http://www.ijsrd.com/articles/IJSRDV6I50198.pdf Vishal Kumar Jaiswal "Experimental Investigation of Process Parameters on Inconel 925 for EDM Process by using Taguchi Method." International Journal for Scientific Research and Development 6.5 (2018): 277-282. ], IJSRD</ref>
* Inconel 939: Gamma prime strengthened to increase weldability

In age hardening or precipitation strengthening varieties, alloying additions of aluminum and [[titanium]] combine with nickel to form the intermetallic compound {{chem2|Ni3(Ti,Al)}} or gamma prime (γ′). Gamma prime forms small cubic crystals that inhibit slip and creep effectively at elevated temperatures.

==See also==
{{commonscat}}
{{wiktionary}}
* [[Hastelloy]]
* [[Incoloy]]
* [[Monel]]
* [[Nichrome]]
* [[Nimonic]]
* [[Stellite]]

==References==
{{reflist|25em}}

[[Category:Nickel–chromium alloys]]
[[Category:Refractory metals]]
[[Category:Superalloys]]
[[Category:Aerospace materials]]
[[Category:Nickel alloys]]
[[Category:Chromium alloys]]