ThePipingMart Blog Grades Incoloy Alloy 25-6HN (UNS N08367) – Composition, Properties, and Uses

Incoloy Alloy 25-6HN (UNS N08367) – Composition, Properties, and Uses

Incoloy 25-6HN

If you are in the engineering, construction, or chemical production industry, you have probably heard of the metal alloy Incoloy. Specifically, you might have come across a variation known as Incoloy 25-6HN. This alloy is known for its unique properties that suit extreme environments. This blog post will closely examine what Incoloy 25-6HN is, its composition, physical and mechanical properties, uses hardness, and heat treatment.

Incoloy 25-6HN Composition

Incoloy is a nickel-based alloy containing copper, iron, chromium, and molybdenum. The 25-6HN variation has additional elements such as nitrogen and possesses higher nickel and chromium content. The composition of this alloy is what gives it its exceptional properties.

Element Content (%)
Iron, Fe 41.3
Nickel, Ni 24.3
Chromium, Cr 20.6
Molybdenum, Mo 6.3
Others Remainder

Incoloy 25-6HN Physical Properties

Incoloy 25-6HN is known for its excellent corrosion resistance, especially in acidic environments such as sulfuric and hydrochloric acid. It is also oxidation-resistant and can withstand high temperatures of up to 1000°C. This makes it an ideal material for chemical and petrochemical plants and aircraft engines.

Properties Metric Imperial
Density 8.02 gm/cm3 0.290 lb/in3

Incoloy 25-6HN Mechanical Properties

Besides being resilient to corrosion and high temperatures, Incoloy 25-6HN has excellent mechanical properties. It is challenging, malleable, and has high tensile and yield strength. It also has a low thermal expansion coefficient, meaning it expands minimally when exposed to high temperatures.

Properties Metric Imperial
Tensile strength(annealed) 552 MPa 80 ksi
Yield strength(annealed) 276 MPa 40 ksi
Elongation at Break 45% 45%
Hardness, Rockwell B 90 90

Incoloy 25-6HN Equivalents

UNS N08367 ASTM B 688 ASTM B 691 ASTM B 564 ASTM B 472
ASTM B 676 ASTM B 675 ASTM B 804 ASTM B 366 ASTM B 462

Incoloy 25-6HN Uses

Thanks to its unique mechanical and physical properties, Incoloy 25-6HN is used in various industries. It is commonly used in the aerospace industry for producing turbine blades, aircraft engines, rocket engines, and heat exchangers. In the chemical and petrochemical industry, it finds use in producing reaction vessels, heat exchangers, and pipes. It also makes chemical processing equipment, such as evaporators and tanks.

Incoloy 25-6HN Hardness

Incoloy 25-6HN has a maximum hardness of 277HB. This hardness can be further controlled by adjustment of the annealing temperature and time, giving it even better mechanical and physical properties when used in specific applications.

Incoloy 25-6HN Heat Treatment

Incoloy 25-6HN can be hardened by heat treatments such as annealing, quenching, and tempering. The heat treatment of Incoloy 25-6HN is critical in determining the alloy’s final mechanical and physical properties. It is important to use the right temperature and duration of heat treatment to attain the desired properties.


In conclusion, Incoloy 25-6HN is a robust alloy used in various industries. Its unique composition and physical and mechanical properties make it an ideal material for use in extreme environments. The alloy’s excellent corrosion resistance, melting point, and strength make it suitable for petrochemical plants, aerospace, and chemical industries. Understanding the composition, properties, and heat treatment of Incoloy 25-6HN can help engineers and manufacturers create solid and durable materials to be used in highly demanding applications.

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