Nickel-Iron-Chromium Alloys for High-Temperature, Chemical, and Industrial Service

Incoloy is a family of nickel-iron-chromium-based alloys developed for applications requiring a combination of high-temperature strength, oxidation resistance, carburization resistance, corrosion resistance, and structural stability.

Unlike the Inconel family, which is often associated with nickel-rich superalloys and high-performance corrosion or high-temperature applications, Incoloy grades are frequently designed around specific balances of nickel, iron, chromium, and additional alloying elements. Different Incoloy grades serve different operating environments, so the exact grade must be identified before material selection or quotation.

Common Incoloy Grades

Depending on the application, commonly referenced Incoloy grades include:

• Incoloy 800

• Incoloy 800H

• Incoloy 800HT

• Incoloy 825

• Incoloy 901

• Incoloy 925

• Incoloy 330, where applicable to the required product category

Each grade has a different chemical composition, heat-treatment requirement, strengthening mechanism, and application range.

Incoloy 800, 800H, and 800HT

Incoloy 800, 800H, and 800HT are nickel-iron-chromium alloys primarily used for high-temperature structural and process applications.

Incoloy 800

Incoloy 800 is commonly selected for general high-temperature service where resistance to oxidation, carburization, and nitridation is important.

Incoloy 800H

Incoloy 800H is designed for improved high-temperature creep and rupture properties. It is often used in equipment operating under sustained elevated-temperature stress.

Incoloy 800HT

Incoloy 800HT provides more tightly controlled high-temperature performance and is frequently considered for demanding elevated-temperature applications where creep resistance is critical.

Incoloy 825

Incoloy 825, also known as Alloy 825 or UNS N08825, is a nickel-iron-chromium alloy with additions of molybdenum, copper, and titanium. It is widely selected for corrosion resistance in acidic and chemically aggressive environments.

Incoloy 825 is often used where resistance to:

• Sulfuric acid

• Phosphoric acid

• Chloride-containing environments

• Chemical processing solutions

• Stress corrosion cracking

• Intergranular corrosion

is required.

The appropriate grade should be chosen based on the actual chemical concentration, temperature, flow conditions, contaminants, and exposure duration.

Incoloy 925

Incoloy 925, also known as Alloy 925 or UNS N09925, is a precipitation-hardenable nickel-iron-chromium alloy designed to provide a combination of corrosion resistance and high mechanical strength.

It is commonly considered for:

• Oil and gas equipment

• Downhole tools

• High-pressure components

• Sour-service applications

• Valves and fasteners

• Corrosion-resistant structural parts

For oil and gas applications, the buyer should specify the required sour-service standard, hardness limitation, environmental conditions, and qualification requirements.

Typical Chemical Composition

Because Incoloy is an alloy family rather than one single grade, the chemical composition must be specified by grade.

A purchase order should never state only “Incoloy” without identifying the exact grade, UNS number, standard, and product form.

Typical Product Forms

Incoloy alloys may be supplied in forms such as:

• Seamless pipe

• Welded pipe

• Tubes

• Plates

• Sheets

• Bars

• Rods

• Forgings

• Rings

• Fasteners

• Welding products

• Custom-fabricated components

Availability depends on grade, dimensions, manufacturing route, and order quantity.

Common Standards and Designations

Potential specifications may include:

• ASTM B163 — Nickel alloy condenser and heat-exchanger tubes

• ASTM B407 — Nickel-iron-chromium alloy seamless pipe

• ASTM B409 — Nickel-iron-chromium alloy plate, sheet, and strip

• ASTM B514 — Nickel-iron-chromium alloy welded pipe

• ASTM B425 — Nickel-iron-chromium alloy bars

• ASTM B423 — Nickel-iron-chromium-molybdenum-copper alloy seamless pipe and tube, where applicable

• UNS N08800

• UNS N08810

• UNS N08811

• UNS N08825

• UNS N09925

The applicable standard must be matched to the exact grade and product form.

Applications of Incoloy Alloys

Incoloy alloys are used in:

• Heat exchangers

• Chemical processing equipment

• Petrochemical processing

• Furnace components

• Industrial heating systems

• Power generation

• Steam superheaters

• Nuclear process equipment

• Hydrocarbon processing

• Oil and gas production

• Sour-service equipment

• High-temperature piping

• Industrial combustion systems

How to Select the Correct Incoloy Grade

The following questions should be answered before selecting a grade:

1. What is the operating temperature?

2. Is the environment oxidizing, reducing, carburizing, or nitriding?

3. Is the material exposed to sulfuric or phosphoric acid?

4. Is chloride corrosion a concern?

5. Is high creep strength required?

6. Is precipitation hardening required?

7. Is the product welded, forged, machined, or cold-formed?

8. Is sour-service compliance required?

9. What standard and inspection level are required?

10. What dimensions and delivery condition are needed?

Request an Incoloy Alloy Quotation

Please specify the exact Incoloy grade, such as Incoloy 800, 800H, 800HT, 825, or 925, together with the product form, dimensions, standard, quantity, and application conditions.

Visit Alloysfactory: https://www.alloysfactory.com/

Alloysfactory can evaluate the requested grade and help confirm the appropriate supply form, technical documentation, inspection requirements, and delivery arrangement.