When thinking of materials for high performance in rigorous applications, the name of Inconel material automatically comes to mind. As the Inconel material is very expensive, the use is of limited nature. Because of this Inconel material is generally less familiar as compared to Steel or Aluminum. In this article, we will explore some basics of this unique nickel alloy.
What is Inconel?
Inconel materials are nickel-chrome-based superalloys. Inconel has high corrosion resistance, oxidation resistance, strength at high temperatures, and creep resistance. Inconel is able to withstand elevated temperatures and extremely corrosive environments.
The term “Inconel” is a registered trademark of Special Metals Corporation, USA. In 1932, the first Inconel alloy was formulated.
Composition of Inconel Alloy
The chemical composition of Inconel material varies with grade. As this is a nickel alloy, the Nickel percentage is more. Other elements present in Inconel alloy material are:
Chromium
Iron
Cobalt
Molybdenum
Titanium
Niobium
Refer to table 1 below which provides the chemical composition of some of the common Inconel material grades (Reference: https://en.wikipedia.org/wiki/Inconel). All values of elements are provided in mass %.
Inconel Grade
Nickel (Ni)
Chromium (Cr)
Iron (Fe)
Molybdenum (Mo)
Niobium (Nb) & Tantalum(Ta)
Cobalt (Co)
Manganese (Mn)
Copper (Cu)
Aluminum (Al)
Titanium (Ti)
Silicon (Si)
Carbon (C)
Sulphur (S)
Phosphorous (P)
Boron (B)
600
≥72
14-17
6-10
–
–
–
≤1.0
≤0.5
–
–
≤0.5
≤0.15
≤0.015
–
–
617
44.2–61
20-24
≤3
8-10
–
10-15
≤0.5
≤0.5
0.8-1.5
≤0.6
≤0.5
0.05-0.15
≤0.015
≤0.015
≤0.006
625
≥58
20-23
≤5
8-10
3.15-4.15
≤1
≤0.5
–
≤0.4
≤0.4
≤0.5
≤0.1
≤0.015
≤0.015
–
690
≥58
27-31
7-11
–
–
–
≤0.5
≤0.5
–
–
≤0.5
≤0.05
≤0.015
–
–
Nuclear grade 690
≥58
28-31
7-11
–
–
≤0.1
≤0.5
≤0.5
–
–
≤0.5
≤0.04
≤0.015
–
–
718
50–55
17-21
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
≥70
14-17
5-9
–
0.7-1.2
≤1.0
≤1.0
≤0.5
0.4-1.0
2.25-2.75
≤0.5
≤0.08
≤0.01
–
–
Table 1: Composition of Inconel Alloy
Properties of Inconel Material
Inconel is characterized by its ability to withstand very high temperatures. Inconel alloy maintains excellent strength even at elevated temperatures. A thick and stable protective oxide layer is formed when heated which provides excellent corrosion resistance even at high temperatures. For very high-temperature applications when steel material succumbs to creep, Inconel material is an ideal choice.
The main reason for Inconel’s very high-temperature resistance is due to the formation of an intermetallic compound Ni3Nb in the gamma double prime (ɣ’’) phase. This intermetallic phase acting as a ‘glue’ on the grain boundaries, prevents the grains from increasing in size when heated to high temperatures. Gamma prime forms small cubic crystals that inhibit slip and creep effectively at elevated temperatures.
The Mechanical and Physical properties of Inconel alloy 625 are provided below in Fig. 1:
Fig. 1: Physical and Mechanical Properties of Inconel 625 alloy
Inconel Alloy Material Grades
Inconel material has a variety of grades varying in composition and properties developed for specific applications. The common Inconel grades are as follows:
Inconel 188: Used widely for commercial gas turbine and aerospace applications.
Inconel 230: Used mainly by the power, aerospace, chemical processing, and industrial heating industries.
Inconel 600: Solid solution strengthened.
Inconel 601
Inconel 617: Used in ASME Boiler and Pressure Vessel Code for high-temperature nuclear applications such as molten salt reactors.
INCONEL alloy is designated as UNS N06625, Werkstoff Number 2.4856, and ISO NW6625. The NACE MR-01-75 standards list Inconel material. The Inconel material products are manufactured in all standard mill forms including rod, bar, wire, wire rod, plate, sheet, strip, shapes, pipes, tubular products, and forging stock.
The most widespread application of Inconel alloys is found in the aerospace industry. The space shuttle, Rocket engines, 3D printing technology, etc use Inconel. The nuclear industry also uses a lot of various Inconel grades. Other uses of Inconel alloys include:
Both Inconel and Monel have Nickel as their primary element. However, there are many differences between the two nickel alloys. The main differences between Inconel and Monel are provided in Table 2 below:
Parameter
Inconel
Monel
Definition
Inconel is a nickel-chromium based superalloy
Monel is Nickel-copper based alloy
Maximum Nickel Content
Inconel roughly has 72% nickel in the base material.
Monel has around 67% nickel in the composition.
Price
Inconel is more expensive than Monel.
Monel is relatively cheaper than Inconel.
Elevated temperature corrosion resistance properties
Inconel has superior corrosion resistance properties at elevated temperatures.
At lower temperatures, the corrosion resistance of Monel is preferred because of its low cost.
I am a Mechanical Engineer turned into a Piping Engineer. Currently, I work in a reputed MNC as a Senior Piping Stress Engineer. I am very much passionate about blogging and always tried to do unique things. This website is my first venture into the world of blogging with the aim of connecting with other piping engineers around the world.
3 thoughts on “What is Inconel Material? Composition, Properties, Grades, and Applications of Inconel”
Why Alloy 825 (UNS N08825) not listed. It is also a Inconel Material.
is an austenitic nickel-iron-chromium alloy with additions of molybdenum, copper and titanium.
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Why Alloy 825 (UNS N08825) not listed. It is also a Inconel Material.
is an austenitic nickel-iron-chromium alloy with additions of molybdenum, copper and titanium.
Added
Hi,
I believe monel has better performance than inconel in see water ( salt water )
Are you agree?
Would you please have a compare between incinel and hestalloy too?
Fhanks