ThePipingMart Blog Grades 901 Incoloy Alloy (N90901) – Composition, Properties and Uses

901 Incoloy Alloy (N90901) – Composition, Properties and Uses

Incoloy 901

Super Alloy Inconel 901 is an age-hardenable nickel-iron-chromium alloy with high strength and resistance to oxidation, carburization, and other forms of high-temperature corrosion. It has a very low carbon content, making it ideal for applications where thermal cycling or welding is required. It also has excellent mechanical properties at ambient and elevated temperatures, making it an attractive option for many engineering solutions. This post will look at the composition, chemical properties, physical properties, uses corrosion resistance, heat resistance, heat treatment, machining, and welding of Incoloy 901.

Incoloy 901 Composition

Incoloy 901 is composed mainly of iron (Fe), chromium (Cr), nickel (Ni), molybdenum (Mo), sulfur (S), silicon (Si) and aluminium (Al). The exact percentages of these elements vary depending on the manufacturer and application. This alloy is often used with other alloys, such as stainless steel, to impart additional strength or corrosion resistance.

Element Content (%)
Nickel, Ni 41-43 .5
Chromium, Cr 11-14
Titanium, Ti 2.2-2.75
Silicon, Si 1 max
Manganese, Mn 0.8 max
Copper, Cu 0.5 max
Aluminum, Al 0.35 max
Carbon, C 0.1 max
Phosphorus, P 0.04 max
Sulfur, S 0.04 max
Boron, B 0.01 – 0.02
Iron, Fe Remainder

Incoloy 901 Chemical Properties

The chemical composition of Incoloy 901 makes it highly resistant to oxidation and carburization when exposed to high temperatures. Additionally, its low sulfur content can be welded without producing harmful fumes or hazardous byproducts. Its chromium content also makes it resistant to corrosion from most acids and alkalis.

Incoloy 901 Physical Properties

Regarding physical properties, Incoloy 901 has an excellent tensile strength at ambient and elevated temperatures up to 1600°F/870°C. It also has good fatigue strength, making it suitable for applications requiring cyclic loading conditions, such as turbines or engines. Its ductility allows it to be easily formed into complex shapes while retaining its structural integrity over time.

Properties Metric Imperial
Density 7.8 g/cm³ 0.283 lb/in³

Incoloy 901 Mechanical Properties

Incoloy 901 offers a unique combination of mechanical properties, making it an ideal choice for many applications. The alloy has an ultimate tensile strength of 92 ksi, yield strength of 55 ksi, and good ductility. Additionally, its elongation capabilities average above 60%, providing versatility in its welding and forging performance. The alloy is also highly resistant to oxidation and corrosion in aggressive environments, with a melting point of 2466˚F. This allows for superior machinability for those applications requiring precise pieces. Ultimately, Incoloy 901 makes for an excellent material choice when the strongest tensile and yield qualities are needed, along with good formability.

Material Tensile Strength ksi Yield Strength ksi Elongation in 4D(%) Reduction of Area % Hardness HB
Alloy 901 150 100 12 15 302-388

Incoloy 901 Equivalent

  • AISI 681
  • AISI 682
  • PWA 1002
  • PWA 1003
  • SPS M259

Incoloy 901 Uses

Due to its combination of good mechanical properties at both ambient and high temperatures coupled with its excellent corrosion resistance properties, Incoloy 901 finds many uses in various industries, including aerospace components such as engine blades or exhaust ducts; automotive components such as turbocharger housings; medical implants; valves; fasteners; marine parts; nuclear power plants; and petrochemical plants.

Corrosion Resistance

One of the main benefits of using Incoloy 901 is its excellent corrosion resistance at both room temperature and higher temperatures up to 1600°F/870°C due to its chromium and low carbon content, which prevents oxidation when exposed to air or water vapour environments. This alloy is also resistant to most organic acids except hydrofluoric acid and chloride-induced pitting corrosion when exposed to certain concentrations of chlorides such as sodium chloride or magnesium chloride solutions.

Heat Treatment

In order to achieve optimal mechanical properties, a specialized heat-treating process must be performed on Incoloy 901, which involves heating the material at 1125 ° F / 604 ° C followed by rapid cooling. This process helps improve the overall tensile strength, fatigue strength, ductility, hardness, creep rupture strength, creep deformation limit, stress rupture limit, Yield Strength, Elongation Limit Modulus Of Elasticity And Density Of The Alloy. The heat treatment process can further enhance the already outstanding corrosion resistance qualities by increasing the amount of chromium present on the surface, which increases the alloy’s pitting resistance even further.


Machining Incoloy 901 requires special tools due to its hardening nature. High-speed steel tools are recommended for turning operations, while carbide tools should be used for drilling operations. A coolant should always be used during machining processes to reduce tool wear.


Welding incoloy 901 requires special attention due To Its Hardening Nature As Well As Low Carbon Content, Which Can Lead To Porosity If Not Handled With Care. The Recommended Welding Process Is Gas Tungsten Arc Welding Or Gas Metal Arc Welding Using An Inert Gas Shield Such As Argon To Prevent Oxygen And Contaminants From Entering The Weld Pool During The Process. Preheat And Post Heat Treatments Should Be Carried Out Whenever Possible To Reduce Thermal Stress On The Part During The Welding Process.


In conclusion, incoloy901 offers many benefits, including high-temperature strength, exceptional corrosion resistance against most organic acids except hydrofluoric acid, good weldability with minimal risk of porosity formation due To Its Low Carbon Content And Specialized Heat Treatment Procedure That Enhances All Of Its Mechanical Properties Making It An Ideal Choice For Many Engineering Applications Requiring High-Temperature Performance And Corrosion Resistance. Furthermore, Its Formability Allows For Complex Shapes To Be Produced While Retaining Structural Integrity Over Time Which Makes It Especially Suitable For Aerospace Components Such As Turbine Blades Or Exhaust Ducts Where Weight Savings Are Crucial Factors In Design Considerations. Intended Audience: Mechanical engineers looking for information about incoloy901’s compositional makeup along with its uses, chemical & physical properties & other essential considerations related to working with this particular alloy type will find this article informative & helpful!

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