Inconel: Properties, Uses and Processing Examples

This page explains the characteristics and applications of Inconel, one of the materials used for processing, as well as examples of processing at TDC.

What is Inconel?

Inconel® is a trademarked name for a type of nickel alloy manufactured by Special Metals Corporation. The alloy contains additives such as chromium, iron, niobium, and molybdenum. Based on the composition of these additives, different types of Inconel are classified, including Inconel 600 (Alloy 600), Inconel 625 (Alloy 625), and Inconel 718 (Alloy 718).

Characteristics, Properties, and Qualities of Inconel

Inconel is primarily known for its excellent heat resistance, corrosion resistance, oxidation resistance, and creep strength. It also features low thermal conductivity and maintains high strength even at elevated temperatures.

Regarding heat resistance, while stainless steel can maintain strength up to approximately 500℃, Inconel retains its high strength even at temperatures around 700℃.

However, because Inconel exhibits high strength even during machining, it is important to note that tools tend to wear more quickly. Additionally, the heat generated during machining does not dissipate easily, which can damage tools due to heat exposure, making Inconel a difficult-to-machine material.

For those who want to learn more about difficult-to-machine materials, please check the following article:

Difficult-to-Machine Materials: Basic Knowledge and Types

Types and Applications of Inconel

Inconel is an alloy primarily composed of nickel, but due to variations in the addition of elements such as molybdenum and niobium, it is classified into several types. Below, we introduce the composition, characteristics, and applications of the representative types of Inconel.
(Source: Special Metals Corporation)

Inconel 600 (Alloy 600)

Inconel 600 (Alloy 600) contains a high percentage of nickel and is known for its excellent resistance to corrosion from high-purity water and alkaline solutions, as well as its resistance to stress corrosion cracking caused by chloride ions. It also exhibits good oxidation resistance at high temperatures.

Inconel 600 is used in applications that require resistance to corrosion and heat, such as chemical engineering equipment and heating components.

Composition
Ni	Cr	Fe	C	Mn	S	Si	Cu
72.0min	14.0-17.0	6.0-10.0	0.15max	1.00max	0.015max	0.50max	0.50max

Note: The values in the table are reference guidelines.

Inconel 625 (Alloy 625)

Inconel 625 (Alloy 625) contains a high amount of chromium, molybdenum, and niobium, providing excellent resistance to a wide range of corrosive environments. Additionally, it is known for its relatively good weldability compared to other Inconel alloys.

Due to its excellent resistance to pitting and crevice corrosion, as well as its high tensile strength, Inconel 625 is widely used in chemical and seawater engineering applications.

Composition
Ni	Cr	Fe	Mo	Nb+Ta	C	Mn	Si
58.0min	20.0-23.0	5.0max	8.0-10.0	3.15-4.15	0.10max	0.50max	0.50max

Composition
P	S	Al	Ti	Co
0.015max	0.015max	0.40max	0.40max	1.0max

Note: The values in the table are reference guidelines.

Inconel 718 (Alloy 718)

Inconel 718 contains a significant amount of molybdenum and niobium, along with small amounts of aluminum and titanium. It maintains high strength and corrosion resistance over a wide temperature range, from approximately -250℃ to 700℃. In addition, it is characterized by excellent tensile strength, fatigue strength, creep strength, and fracture toughness.

Typical applications of Inconel 718 include aircraft components such as gas turbine engines, casings, high-strength bolts, and springs.

Composition
Ni	Cr	Fe	Mo	Nb+Ta	C	Mn	Si
50.0-55.0	17.0-21.0	Balance	2.80-3.30	4.75-5.50	0.08 max	0.35 max	0.35 max

Composition
P	S	Al	Ti	Co	B	Cu
0.015max	0.015max	0.20-0.80	0.65-1.15	1.0max	0.006max	0.30max

Note: The values in the table are reference guidelines.

Difference Between Inconel and Hastelloy

Hastelloy® is a trademarked nickel alloy by HAYNES International, Inc. Like Inconel, Hastelloy exhibits excellent corrosion and heat resistance, and it is also considered a difficult-to-machine material.

However, Inconel and Hastelloy differ in the specific properties they excel at. The key differences are as follows:

• Inconel: A nickel alloy specialized for high-temperature resistance.
• Hastelloy: A nickel alloy specialized for corrosion resistance.

Inconel maintains high strength even at elevated temperatures, whereas Hastelloy, while excellent in corrosion resistance, does not retain strength as well under high heat compared to Inconel. For applications where corrosion resistance is a priority, Hastelloy is the preferred choice.

However, there are Inconel variants with enhanced corrosion resistance and Hastelloy variants with improved heat resistance. Therefore, when selecting materials, it is advisable to consult with specialists.

For more information about Hastelloy, please check the following article:

Hastelloy: Features, Applications, and Processing Examples

Inconel processing at TDC

Here are examples of Inconel grinding processing at TDC.
Please note that due to confidentiality agreements, there are many cases that we cannot share. If you have any questions regarding processability, feel free to contact us.

For surface roughness results of other materials, please refer to the page below.
We invite you to check it out.
Surface Roughness Achievements at TDC

Inconel Processing: “Mirror Finish of Inconel 718 Substrate”

• Size: φ150 x 10t
• Specification/Precision: Ra1nm or less
• Material: Inconel 718
• Processing: After thickness adjustment by surface grinding, both sides were finished to a mirror finish (Ra1nm).

At TDC, we handle the production of high-precision parts and test specimens made from Inconel. We can also procure materials according to your specifications.

• Size: Manufactured to your desired size
• Specifications/Accuracy: Ra1nm, with geometric tolerances such as flatness and parallelism controlled through polishing.
• Material: Various types of Inconel
• Processing Details: High-precision components made according to your specifications.

For Inconel polishing, please consult TDC.

Inconel is a nickel alloy containing elements such as chromium, iron, niobium, and molybdenum, known for its excellent heat resistance, corrosion resistance, and oxidation resistance. However, due to its difficulty in machining, it requires advanced techniques and expertise to process with high precision.

At TDC, we offer expertise and accumulated knowledge in processing, including polishing, grinding, and cutting techniques, to handle various materials and precision requirements.

If you’ve had difficulty processing Inconel with other companies, feel free to consult with TDC.

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