ThePipingMart Blog Grades AMS 5660 Incoloy Alloy- Composition, Properties, and Uses

AMS 5660 Incoloy Alloy- Composition, Properties, and Uses

AMS 5660

AMS 5660 is a nickel-based alloy widely used in various applications owing to its excellent material properties. It is well-known for its exceptional corrosion resistance, particularly in high-temperature and high-stress environments. In this blog post, we will discuss the composition, physical and mechanical properties, uses, and hardness of AMS5660. We will also delve into its heat treatment process and how it affects the material’s properties.

What is AMS 5660?

AMS 5660 (also known as Incoloy 901 Alloy) is a specification used to define the requirements for high-temperature nickel alloy bars, forgings, and rings. This standard is crucial for the aerospace and aviation industries that operate at elevated temperatures and require superior strength and corrosion resistance. The specification sets guidelines, such as chemical composition, mechanical properties, and heat treatment, to ensure that the alloys meet the rigorous demands of these industries. Adhering to AMS 5660 is essential to maintain safety and quality in these critical applications.

AMS 5660 Composition

AMS 5660 is a nickel-based, chromium-containing alloy that also includes molybdenum and titanium in its composition. The percentage of nickel content in the alloy ranges between 70-80%, while the chromium content is around 15-21%. Molybdenum and titanium enhance the alloy’s mechanical properties, such as tensile strength and resistance to creep deformation.

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

AMS 5660 Physical Properties:

AMS 5660 has excellent physical properties that make it suitable for critical applications. It has a density of 8.1 g/cm3 and a melting point of 1320-1395°C. The alloy has a coefficient of thermal expansion of 13.6×10^-6/°C and a thermal conductivity of 10.1 W/mK.

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

AMS 5660 Mechanical Properties:

AMS 5660 possesses exceptional mechanical properties due to its unique composition. It has a tensile strength of 930 MPa, yield strength of 620 MPa, and elongation of 15%. The alloy’s ability to withstand high-temperature and high-stress environments makes it suitable for applications in gas turbines, nuclear reactors, and chemical processing plants.

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

AMS 5660 Equivalents

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

AMS 5660 Uses

AMS 5660 is widely used in various industrial applications due to its excellent material properties. Its high-temperature and corrosion-resistant traits make it suitable for gas turbine engine components, such as combustor cases, transition ducts, and nozzle diaphragms. The alloy is also used in aerospace for fuel nozzles, thrust reversers, and engine nacelles. AMS 5660 is also employed for high-temperature applications in chemical processing plants and nuclear reactors.

AMS 5660 Hardness

AMS 5660 has a maximum hardness of 36 HRC when austenitized and quenched. The alloy’s hardness can be further increased through age hardening, which results in additional mechanical strengthening.

AMS 5660 Heat Treatment

AMS 5660 can be heat-treated to achieve optimal material properties. Heat treatment consists of annealing, solutionizing, quenching, and age hardening. The annealing process eliminates stress and improves the alloy’s ductility. The solutionizing process is done to homogenize the alloy’s microstructure, followed by quenching in water or oil to achieve the desired strength. The age-hardening process increases the hardness and strength of the alloy.


AMS 5660 is a nickel-based alloy with excellent material properties that make it suitable for critical industrial applications. Its unique composition, physical and mechanical properties, and heat treatment capabilities make it ideal for gas turbines, nuclear reactors, and chemical processing plants. However, users must know the alloy’s limitations, such as susceptibility to hydrogen embrittlement and stress-corrosion cracking. Still, when used correctly, AMS 5660 is a reliable material that delivers exceptional performance.

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