Inconel is a registered trademark of
Special Metals Corporation for a family of
austenitic nickel
Nickel is a chemical element with symbol Ni and atomic number 28. It is a silvery-white lustrous metal with a slight golden tinge. Nickel is a hard and ductile transition metal. Pure nickel is chemically reactive but large pieces are slow ...
-
chromium
Chromium is a chemical element with the symbol Cr and atomic number 24. It is the first element in group 6. It is a steely-grey, lustrous, hard, and brittle transition metal.
Chromium metal is valued for its high corrosion resistance and h ...
-based
superalloy
A superalloy, or high-performance alloy, is an alloy with the ability to operate at a high fraction of its melting point. Several key characteristics of a superalloy are excellent mechanical strength, resistance to thermal creep deformation, ...
s.
Inconel alloys are oxidation-
corrosion-resistant materials well suited for service in extreme environments subjected to pressure and heat. When heated, Inconel forms a thick, stable,
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
Creep, Creeps or CREEP may refer to:
People
* Creep, a creepy person
Politics
* Committee for the Re-Election of the President (CRP), mockingly abbreviated as CREEP, an fundraising organization for Richard Nixon's 1972 re-election campaign
Art ...
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.
[INCONEL alloy 718](_blank)
Special Metals Corporation
Inconel alloys are typically used in high temperature applications. Common trade names for
* Inconel Alloy 625 include:
Inconel 625, Chronin 625, Altemp 625, Haynes 625, Nickelvac 625 and Nicrofer 6020.
* Inconel Alloy 600 include: NA14, N06600, BS3076, 2.4816, NiCr15Fe (FR), NiCr15Fe (EU) and NiCr15Fe8 (DE).
* Inconel 718 include: Nicrofer 5219, Superimphy 718, Haynes 718, Pyromet 718, Supermet 718, and Udimet 718.
History
The Inconel family of alloys was first developed before December 1932, when its
trademark
A trademark (also written trade mark or trade-mark) is a type of intellectual property consisting of a recognizable sign, design, or expression that identifies products or services from a particular source and distinguishes them from oth ...
was registered by the
International Nickel Company of Delaware and New York.
A significant early use was found in support of the development of the
Whittle jet engine,
during the 1940s by research teams at Henry Wiggin & Co of
Hereford, England a subsidiary of the
Mond Nickel Company,
which merged with
Inco in 1928. The Hereford Works and its properties including the Inconel trademark were acquired in 1998 by
Special Metals Corporation.
Specific data
Composition
Inconel alloys vary widely in their compositions, but all are predominantly nickel, with chromium as the second element.
Properties
Inconel alloys are
oxidation
Redox (reduction–oxidation, , ) is a type of chemical reaction in which the oxidation states of substrate change. Oxidation is the loss of electrons or an increase in the oxidation state, while reduction is the gain of electrons or a ...
- and
corrosion
Corrosion is a natural process that converts a refined metal into a more chemically stable oxide. It is the gradual deterioration of materials (usually a metal) by chemical or electrochemical reaction with their environment. Corrosion engi ...
-resistant materials well suited for service in extreme environments subjected to high mechanical loads. When heated, Inconel forms a thick and stable
passivating oxide layer protecting the surface from further attack. Inconel retains strength over a wide temperature range, attractive for high-temperature applications where
aluminium
Aluminium (aluminum in AmE, American and CanE, Canadian English) is a chemical element with the Symbol (chemistry), symbol Al and atomic number 13. Aluminium has a density lower than those of other common metals, at approximately o ...
and
steel would succumb to
creep
Creep, Creeps or CREEP may refer to:
People
* Creep, a creepy person
Politics
* Committee for the Re-Election of the President (CRP), mockingly abbreviated as CREEP, an fundraising organization for Richard Nixon's 1972 re-election campaign
Art ...
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 or precipitation-strengthening varieties, small amounts of
niobium combine with
nickel
Nickel is a chemical element with symbol Ni and atomic number 28. It is a silvery-white lustrous metal with a slight golden tinge. Nickel is a hard and ductile transition metal. Pure nickel is chemically reactive but large pieces are slow ...
to form the
intermetallic compound Ni
3Nb or
gamma double prime (γ″). Gamma prime forms small cubic crystals that inhibit
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 , and continues to grow after 72 hours of exposure.
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, with only the final steps being performed after age hardening. However some claim that Inconel can be machined extremely quickly with very fast spindle speeds using a multifluted ceramic tool with small depth of cut at high feed rates as this causes localised heating and softening in front of the flute.
External
threads
Thread may refer to:
Objects
* Thread (yarn), a kind of thin yarn used for sewing
** Thread (unit of measurement), a cotton yarn measure
* Screw thread, a helical ridge on a cylindrical fastener
Arts and entertainment
* ''Thread'' (film), 2016 ...
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. Inconel 718 can also be roll-threaded after full aging by using
induction heat
Induction heating is the process of heating electrically conductive materials, namely metals or semi-conductors, by electromagnetic induction, through heat transfer passing through an induction coil that creates an electromagnetic field within th ...
to without increasing the grain size. Holes with internal threads are made by threadmilling. Internal threads can also be formed using a sinker
electrical discharge machining
Electrical discharge machining (EDM), also known as spark machining, spark eroding, die sinking, wire burning or wire erosion, is a metal
fabrication process whereby a desired shape is obtained by using electrical discharges (sparks). Material i ...
(EDM).
More often than machining, water-jet or laser
grinding is a preferred and economical method for forming nickel alloy components to shape and finish. Due to the hardness of the abrasives used, the grinding wheels are not as affected by the material work hardening and remain sharp and durable.
Joining
Welding of some Inconel alloys (especially the gamma prime precipitation hardened family; e.g., Waspalloy and X-750) can be difficult due to cracking and microstructural segregation of alloying elements in the
heat-affected zone
In fusion welding, the heat-affected zone (HAZ) is the area of base material, either a metal or a thermoplastic, which is not melted but has had its microstructure and properties altered by welding or heat intensive cutting operations. The heat ...
. 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.
Uses
Inconel is often encountered in extreme environments. It is common in
gas turbine
A gas turbine, also called a combustion turbine, is a type of continuous flow internal combustion engine. The main parts common to all gas turbine engines form the power-producing part (known as the gas generator or core) and are, in the directio ...
blades, seals, and combustors, as well as
turbocharger
In an internal combustion engine, a turbocharger (often called a turbo) is a forced induction device that is powered by the flow of exhaust gases. It uses this energy to compress the intake gas, forcing more air into the engine in order to pr ...
rotors and seals, electric submersible well pump motor shafts, high temperature fasteners, chemical processing and
pressure vessels,
heat exchanger
A heat exchanger is a system used to transfer heat between a source and a working fluid. Heat exchangers are used in both cooling and heating processes. The fluids may be separated by a solid wall to prevent mixing or they may be in direct conta ...
tubing, steam generators and core components in nuclear
pressurized water reactors,
natural gas processing with contaminants such as H
2S and CO
2,
firearm sound suppressor blast baffles, and
Formula One
Formula One (also known as Formula 1 or F1) is the highest class of international racing for open-wheel single-seater formula racing cars sanctioned by the Fédération Internationale de l'Automobile (FIA). The World Drivers' Championship ...
,
NASCAR
The National Association for Stock Car Auto Racing, LLC (NASCAR) is an American auto racing sanctioning and operating company that is best known for stock car racing. The privately owned company was founded by Bill France Sr. in 1948, and h ...
,
NHRA, and
APR, LLC exhaust systems. It is also used in the turbo system of the 3rd generation
Mazda RX7, and the exhaust systems of high powered
Wankel engined
Norton motorcycles where exhaust temperatures reach more than . Inconel is increasingly used in the boilers of waste
incinerators. The
Joint European Torus
The Joint European Torus, or JET, is an operational magnetically confined plasma physics experiment, located at Culham Centre for Fusion Energy in Oxfordshire, UK. Based on a tokamak design, the fusion research facility is a joint European p ...
and
DIII-D tokamaks' vacuum vessels are made of Inconel. Inconel 718 is commonly used for
cryogenic storage tanks, downhole shafts, wellhead parts, and in the aerospace industry -- where it has become a prime candidate material for constructing heat resistant turbines.
Aerospace
*The
Space Shuttle
The Space Shuttle is a retired, partially reusable low Earth orbital spacecraft system operated from 1981 to 2011 by the U.S. National Aeronautics and Space Administration (NASA) as part of the Space Shuttle program. Its official program na ...
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 nuts are encased on the outside of the solid rocket boosters, at launch explosives separated the nuts releasing the Shuttle from its launch platform.
*
North American Aviation
North American Aviation (NAA) was a major American aerospace manufacturer that designed and built several notable aircraft and spacecraft. Its products included: the T-6 Texan trainer, the P-51 Mustang fighter, the B-25 Mitchell bomber, the ...
constructed the skin of the
North American X-15
The North American X-15 is a hypersonic rocket-powered aircraft. It was operated by the United States Air Force and the National Aeronautics and Space Administration as part of the X-plane series of experimental aircraft. The X-15 set spe ...
Rocket-powered aircraft out of Inconel X/750 alloy.
*
Rocketdyne
Rocketdyne was an American rocket engine design and production company headquartered in Canoga Park, California, Canoga Park, in the western San Fernando Valley of suburban Los Angeles, California, Los Angeles, in southern California.
The Rocke ...
used Inconel X-750 for the thrust chamber of the
F-1 rocket engine
The F-1, commonly known as Rocketdyne F1, was a rocket engine developed by Rocketdyne. This engine uses a gas-generator cycle developed in the United States in the late 1950s and was used in the Saturn V rocket in the 1960s and early 1970s. Five ...
used in the first stage of the
Saturn V
Saturn V is a retired American super heavy-lift launch vehicle developed by NASA under the Apollo program for human exploration of the Moon. The rocket was human-rated, with three stages, and powered with liquid fuel. It was flown from 1 ...
booster.
*
SpaceX uses inconel (Inconel 718) in the engine manifold of their
Merlin engine which powers the
Falcon 9
Falcon 9 is a partially reusable medium lift launch vehicle that can carry cargo and crew into Earth orbit, produced by American aerospace company SpaceX.
The rocket has two stages. The first (booster) stage carries the second stage and pa ...
launch vehicle
A launch vehicle or carrier rocket is a rocket designed to carry a payload (spacecraft or satellites) from the Earth's surface to outer space. Most launch vehicles operate from a launch pads, supported by a launch control center and syste ...
.
[>]
*In a first for
3D printing
3D printing or additive manufacturing is the construction of a three-dimensional object from a CAD model or a digital 3D model. It can be done in a variety of processes in which material is deposited, joined or solidified under computer ...
, the SpaceX
SuperDraco rocket engine
A rocket engine uses stored rocket propellants as the reaction mass for forming a high-speed propulsive Jet (fluid), jet of fluid, usually high-temperature gas. Rocket engines are reaction engines, producing thrust by ejecting mass rearward, i ...
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 .
[
]
* SpaceX cast the Raptor rocket engine manifolds from SX300, later SX500, which are monocrystal nickel alloy (improvement over older Inconel alloys).[''SpaceX Casting Raptor Engine Parts from Supersteel Alloys'' Feb 2019]
/ref>
Automotive
* Tesla is now claiming to use Inconel in place of steel in the main battery pack contactor of its 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
The ampere (, ; symbol: A), often Clipping (morphology), shortened to amp,SI supports only the use of symbols and deprecates the use of abbreviations for units. is the unit of electric current in the International System of Units (SI). One amp ...
s, allowing for an increase in power output (acceleration) Tesla refers to as "Ludicrous Mode
The Tesla Model S is a battery-powered liftback car serving as the flagship model of Tesla, Inc. The Model S features a dual-motor, all-wheel drive layout, although earlier versions of the Model S featured a rear-motor and rear-wheel drive la ...
".
*Ford Motor Company
Ford Motor Company (commonly known as Ford) is an American multinational automobile manufacturer headquartered in Dearborn, Michigan, United States. It was founded by Henry Ford and incorporated on June 16, 1903. The company sells automobiles ...
is using Inconel to make the turbine wheel in the turbocharger of its EcoBlue diesel engines introduced in 2016.
*The exhaust valves on NHRA Top Fuel and Funny Car drag racing engines are often made of Inconel. Inconel is also used in the manufacture of exhaust valves in high performance aftermarket turbo and Supercharged Mazda Miata engine builds (see Flyin' Miata).
* Ford Australia used Inconel valves in their turbocharged Barra engines. These valves have been proven very reliable, holding in excess of 1900 horsepower.
* 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.
* 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 of mass from the vehicle.
* DeLorean Motor Company offers Inconel replacements for failure prone OE trailing arm bolts on the DMC-12. Failure of these bolts can result in loss of the vehicle.
Rolled Inconel was frequently used as the recording medium by engraving in black box recorders on aircraft.
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
An alloy is a mixture of chemical elements of which at least one is a metal. Unlike chemical compounds with metallic bases, an alloy will retain all the properties of a metal in the resulting material, such as electrical conductivity, ductilit ...
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: Solid solution strengthened
* Inconel 601:
* Inconel 617: Solid solution strengthened (nickel-chromium-cobalt-molybdenum), high-temperature strength, corrosion and oxidation resistant, high workability and weldability. Incorporated in ASME Boiler and Pressure Vessel Code for high temperature nuclear applications such as molten salt reactors April, 2020.
* Inconel 625: Acid resistant, good weldability. The LCF version is typically used in bellows.
* Inconel 690: Low cobalt content for nuclear applications, and low resistivity
* Inconel 713C: Precipitation hardenable nickel-chromium base cast alloy
* Inconel 718: Gamma double prime strengthened with good weldability
* Inconel X-750: Commonly used for gas turbine components, including blades, seals and rotors.
* Inconel 751: Increased aluminium content for improved rupture strength in the 1600 °F range
* Inconel 792: Increased aluminium content for improved high temperature corrosion resistant properties, used especially in gas turbines
* Inconel 907
* Inconel 909
* Inconel 706
* Inconel 939: Gamma prime strengthened to increase weldability.
* Inconel 925: Inconel 925 is a nonstabilized austenitic stainless steel with low carbon content.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
In age hardening or precipitation strengthening varieties, alloying additions of aluminum and titanium
Titanium is a chemical element with the Symbol (chemistry), symbol Ti and atomic number 22. Found in nature only as an oxide, it can be reduced to produce a lustrous transition metal with a silver color, low density, and high strength, resista ...
combine with nickel to form the intermetallic compound or gamma prime (γ′). Gamma prime forms small cubic crystals that inhibit slip and creep effectively at elevated temperatures.
See also
* Hastelloy
* Incoloy
* Monel
* Nimonic Nimonic is a registered trademark of Special Metals Corporation that refers to a family of nickel-based high-temperature low creep superalloys. Nimonic alloys typically consist of more than 50% nickel and 20% chromium with additives such as titan ...
* Stellite
References
{{reflist, 35em
Metals
Nickel–chromium alloys
Refractory metals
Superalloys
Aerospace materials
Nickel alloys
Chromium alloys