Inconel
is a group of nickel-based superalloys that are highly resistant to corrosion
and oxidation under high temperature and high pressure operating conditions. At
high temperatures, a stable, stable, and passive layer of oxide forms on the
surface of Inconel alloys, which prevents further corrosion. Inconel maintains
its strength over a wide range of temperatures. This alloy has a special
application in situations where aluminum and stainless steel can not be used
due to the possibility of creep at high temperatures.
The Inconel
brand is registered by Special Metals Co.
This alloy is a family of solid-soluble
nickel-chromium base alloys and is generally used for high temperature
applications.
Inconel is also called "inco" and
"iconel".
Inconel's other trademarks include Inconel
625, Chronin625 Altemp 625, Haynes 625, Nickelvac 625. This alloy was first
developed by a research team in the United Kingdom.
Inconel alloys
Inconel alloys are resistant to oxidation. These alloys have the
ability to maintain structural integrity at high temperatures. There are
several Inconel alloys. These alloys are used in cases that require properties
that do not easily lead to severe corrosion or water corrosion and corrosion
cracking. While any change in Inconel has unique features. This makes inconels
effective in a variety of conditions, most of which are used in the chemical
industry.
Inconel is often used in
marine applications due to its extreme resistance to sodium chloride (salt) at
various temperatures. Therefore, Inconel is a good choice for processes that
use a salt plant or salt plant near the ocean. It is also used for cases where
the temperature is very high, such as heat treatment. It is a substance that is
used specifically for some of the most difficult conditions. Even compared to
stainless steel, Inconel alloy has an extremely high heat resistance.
Alloy inconel has grades 600, 601, 625, 690, 718, 722, and 903.
These alloys are widely known for their corrosion resistance in both high
temperature and water environments. Each alloy has its own advantages, and each
is used in a number of different industries. The Inconel 600 and 601, for
example, are both effective tools in the chemical and food industries, while
the Inconel 718 is more commonly used in the aerospace industry in spacecraft
and rocket engines.
Features of Inconel alloys
The characteristics of Inconel alloys that distinguish it from
other superalloys are as follows.
Resistance to acids such as sulfuric, phosphoric, nitric and
hydrochloric.
There is almost no risk of cracking due to chloride corrosion of
this alloy. Excellent mechanical properties at both very low and very high
temperatures.
Excellent resistance to
pitting corrosion, slit corrosion and intercrystalline corrosion
High resistance to oxidation at high temperatures
Applications of Inconel Alloys
Chemical and petrochemical
processing
Parts that require high
mechanical pressure and seawater exposure
Torch of offshore oil systems
Gas turbines, rocket engines
and space industries
Pollution control equipment
Nuclear reactors
Inconl 600
Inconel 600 is a nickel-chromium alloy that shows high resistance
to corrosive elements. In high temperature conditions, Inconel 600 is strong
against chloride ion cracking or oxidation. This alloy is also resistant to
corrosion caused by pure water. However, Inconel 600 is used in the food
industry and nuclear engineering. Because these alloys retain their structure
in applications that create irreversible corrosion.
Inconel 601
This Inconel, like the Inconel 600, is resistant to various types
of corrosion and oxidation at high temperatures. However, unlike the 600, this
nickel-chromium alloy also contains aluminum in its composition. This added
element provides excellent properties in very hot environments. Inconel 601 has
a high thermal resistance, which is why it is used in gas turbine components
and petrochemical processing equipment.
Inconl 625
Inconel 625 differs from many other Inconel alloys in that it
combines significant amounts of nickel, chromium and molybdenum. This grade
also has neobium. As a result of using these elements in Inconel composition,
its strength increases. (Without heat treatment on them). Inconel 625 is
resistant to pitting corrosion.
What is the difference between Hestlevi and Inconel? Both Inconel
and Hesteloi have high corrosion resistance and durability. They cost more than
stainless steel, but because of their reliable performance in harsh
environments, nickel alloys are preferred for applications such as geothermal,
nuclear, aerospace.
What is the melting point of Inconel and Hesteloi?
The higher melting point of Inconel is 2600 - 2500 degrees
Fahrenheit (1390 - 1425 degrees Celsius) which Hastelloy melting point.
It has 2460-2410 degrees Fahrenheit (1320-1350 degrees Celsius).
Nickel alloys lose their strength before they reach the melting point, so it is
generally recommended to maintain a normal temperature below this range.
Specification
• Excellent oxidation and corrosion resistance at high
temperatures; Therefore, they are very suitable for working in environments
under high pressure and kinetic energy.
Good corrosion resistance in acidic environments such as sulfuric
and phosphoric acids
Excellent mechanical properties in hot and cold working
environments such as high yield stress (even at temperatures close to 750 °C),
high tensile strength, fatigue resistance, and good creep resistance.
The high-temperature strength of Inconel, depending on its type, is
related to the strength of the solid solution or the strength of the sediment.
In all types of sediment aging or hardening, small amounts of niobium combine
with nickel to form the intermetallic compound gamma prime (Ni3Nb). Gamma prime
forms small cubic crystals that inhibit effective slippage and creep at high temperatures.
The formation of these crystals increases with time.
Inconel machining
The unique mechanical properties of icons make them machined to
make parts used in industry, and these metals, like most superalloys, are
classified as materials with poor machining properties. High stiffness and
strength during machining and at high temperatures in the cutting area cause
the plastic deformation of the cutting edge of the tool. In addition, these
nickel-based alloys contain highly abrasive impurities such as carbide
particles (which increase creep resistance) and also tend to harden during
machining, causing tool wear; Therefore, machining these alloys by traditional
methods is very difficult and achieving a suitable surface quality in some
cases is almost impossible. In these cases, non-traditional methods such as
electrical discharge machining (EDM) and electrochemical machining (ECM) can be
used.
Inconel welding
The welding process of most Inconel alloys is difficult due to
cracking and microstructural separation of alloying elements in the temperature
affected zone (HAZ). To overcome this problem, several special alloys such as
Inconel 625 and Inconel 718 have been designed and developed. The most common
methods of welding icons are tungsten arc welding and electron beam welding.
Lately, new innovations in pulsed microliter welding have also been considered.
applications
• Automotive, arms, aerospace industries
• Common in the manufacture of gas turbine blades
Combustion chamber in jet or turbine rocket
• Offshore oil rigs
• High-pressure valves and fittings for tankers
• Chemical and petrochemical industries and processes
• Turbochargers
• Parts of nuclear equipment such as nuclear reactors
• Pollution control equipment
• Food industry equipment
• Military equipment and advanced defense industries
Inconel alloys
• Inconel 600: Solid solution solidification
• Inconel 625: Acid resistant, good welding capability
Inconel 690: Low in cobalt and low in core applications and
resistivity
• Inconel 718: has the strength of gamma double prime phase, also
has good welding capability
Inconel 751: The amount of aluminum has been increased to improve
the fracture toughness at 1600 Fahrenheit.
• Inconel 792: To improve the high temperature corrosion
properties, the amount of aluminum element has been increased. Used in the
construction of gas turbines.
• Inconel 939: It has strength by gamma prime phase and has good
welding capability.
Introducing Inconel 738 alloy
Inconel-738 (IN-738) superalloy is a non-magnetic nickel-based
alloy superalloy containing 60% nickel, 16% chromium, 8.5% cobalt, and very
small amounts of other metals such as aluminum, titanium, and tungsten. . This
superalloy was produced in 1967 at the Paul DiMerica Research Laboratory
(PDMRL). The purpose of developing this superalloy was to produce a cast alloy
with a stable structure that includes the strength of Inconel 713 superalloy
along with the corrosion resistance and oxidation of the udimet-500 alloy.
Depending on the amount of carbon in it, this superalloy can be divided into
two categories: low carbon (IN-738LC) with a carbon content of 0.9 to 0.18% and
high carbon (IN-738C) with a carbon content of 0.15 to 0.20%. Divided. Optimal
resistance to oxidation and corrosion and excellent high temperature mechanical
properties of Inconel 738 low carbon alloy have led to its widespread use in
various industries. It is mostly used in industries related to gas turbines
such as power generation, petrochemical, aviation and so on. Applications of
IN-738LC include sensitive parts of gas and air turbines such as fixed and
movable blades, discs, integrated wheels, combustion chambers, etc.
Inconl 625
In addition to being a corrosion-resistant alloy against a wide
range of corrosive materials, the Inconel 625 also has a high mechanical
strength (580 MPa yield strength equivalent to the mechanical strength of
hardened MO40 steel). Due to the high percentage of nickel in the Inconel 625
composition, this alloy is resistant to one of the most common types of
corrosion in the oil and gas and petrochemical industries, namely chloride
stress corrosion cracking (Cl-SCC). Inconel 625 also shows excellent resistance
against pitting and crevice corrosion.
Another advantage of Inconel 625 is its unique welding capability.
Due to the stability of the Inconel 625 crystal structure at high temperatures
and the preservation of granulation after re-melting, this alloy is a suitable
option for applications where the need for weld overlay is required. This
advantage makes the parts made of this alloy have good repairability.
Inconel 625 is the most widely used nickel-based alloy in the oil,
gas and petrochemical industries, and in our country, industrialists active in
this field are very interested in using this alloy. High demand in the country
has made Inconel 625 easily available in the domestic market.
Welding
Welding of Inconel 625 alloy is done with TIG, SMAW and GMAW processes.
In welding Inconel 625 to homogeneous alloy and other alloys with different
material, Inconel 625 filler or 112 electrode (with nickel-chromium-molybdenum
combination) is used. In this case, the deposited weld metal with high strength
(similar strength to the base metal), has a high resistance to corrosion and
oxidation in the cryogenic temperature range up to 982 degrees Celsius. In TIG
and SMAW welding processes, Inconel 625 filler (welding parameters similar to
welding of other nickel-chrome fillers) is used, and in GMAW process, 112
electrode is used. The slag from melting electrode 112 has a high hardness that
can be easily removed by impact. After welding this alloy, no post-heating
process is required to maintain strength and ductility.
Inconel 718:
It is one of the nickel base superalloys. Having the appropriate
strength up to 760 ° C is one of the most important features of Inconel 718. In
addition to having the general properties of superalloys, Inconel 718 has high
strength and impact resistance. Due to its resistance to corrosion, oxidation
and creep, Inconel 718 is used in the manufacture of jet engine parts, turbine
blades, thermal equipment for power plants and the petrochemical industry.