Inconel 601 vs Inconel 625 (UNS N06601 vs N06625) | Alloy Comparison & Supplier

Inconel 601 is a Ni-Cr-Fe solid solution strengthened nickel-based superalloy originally designed to provide excellent oxidation resistance and good mechanical strength in high temperature environments. Inconel 625 was originally designed for supersonic aircraft engine combustion chambers. It is a niobium-containing nickel-chromium-molybdenum alloy that uses a composite strengthening mechanism of solid solution strengthening and γ'' phase (Ni₃Nb) strengthening to achieve excellent performance over a wide temperature range from extremely low temperatures (-196°C) to high temperatures (982°C).

Inconel 601 625 material supplier

HT PIPE is a reputable supplier and exporter. Our inventory includes pipes, inconel 601 plates, bars, alongside high-quality fittings, flanges, and fasteners. Reach out today for competitive pricing and detailed specifications-no obligation, just expert support.

Executive Summary: Key Differences at a Glance

While both alloys are high-performance nickel-chromium superalloys, their primary engineering designations differ significantly:

• Inconel 601 (UNS N06601 / 1.4851): A Ni-Cr-Fe alloy with an aluminum addition (1.0–1.7%), optimized specifically for extreme thermal oxidation and carburization resistance up to 1180°C (2150°F).

• Inconel 625 (UNS N06625 / 2.4856): A Ni-Cr-Mo-Nb alloy strengthened by Molybdenum (8–10%) and Niobium (3.15–4.15%), engineered for exceptional mechanical strength, fatigue resistance, and severe aqueous/marine corrosion resistance from -196°C to 982°C (1800°F).

Basic Characteristics Comparison of Inconel 601 vs. Inconel 625

Inconel 601 vs. Inconel 625 Chemical Composition Comparison

alloy 601 and alloy 625 corrosion resistance

Inconel 601's corrosion resistance is primarily reflected in its high-temperature oxidation resistance. A key property of this alloy is its ability to maintain excellent oxidation resistance in environments up to 1180°C. Even under severe thermal cycling conditions, Inconel 601 forms a dense and strongly adherent oxide film with extremely high spalling resistance. It exhibits excellent resistance to a wide range of organic and inorganic compounds, particularly alkaline solutions. It is one of the few materials capable of withstanding highly concentrated magnesium chloride solutions at high temperatures.

Inconel 625, by contrast, demonstrates superior all-around corrosion resistance, particularly in aqueous environments. This alloy exhibits excellent corrosion resistance in a wide range of media, including pitting, crevice, intergranular, and erosion in chloride media. It is also resistant to inorganic acids, as well as alkali and organic acids in both oxidizing and reducing environments.

Inconel 601 vs. Inconel 625 Mechanical Properties Comparison

alloy n06601 and alloy n06625 High-Temperature Performance

Inconel 601 performs impeccably in ultra-high-temperature oxidizing environments. Its high-temperature oxidation resistance is primarily due to the addition of aluminum, which forms a more stable Al₂O₃ oxide film. After 1000 hours of exposure to air at 1000°C, the oxidation weight gain of Inconel 601 is only 1.2 mg/cm² (according to ASTM G54).

Inconel 625 is designed for a wider temperature range, maintaining excellent performance from cryogenic temperatures of -196°C all the way up to 982°C. This alloy's exceptional high-temperature performance is primarily due to solid solution strengthening by molybdenum and the formation of a gamma-ray strengthening phase by niobium. While Inconel 625's oxidation resistance is inferior to that of Inconel 601 at extremely high temperatures (above 1000°C), it offers higher strength and improved creep resistance in the medium- to high-temperature range (600-900°C).

Choose Inconel 601 if:

• Your continuous operating temperature exceeds 1000°C (up to 1180°C).
• The application experiences extreme cyclic heating and cooling without spalling.
• You require equipment for industrial furnaces, heat-treating baskets, radiant tubes, and thermal oxidizers.
• You need a cost-effective solution without expensive Molybdenum or Niobium additions.

Choose Inconel 625 if:

• Operating in aggressive chloride, seawater, sour gas (H₂S), or chemical processing environments.
• High tensile, fatigue, and creep-rupture strengths are required under heavy mechanical loads.
• The application involves aerospace exhaust systems, offshore riser clamps, marine fasteners, or nuclear components.
• Compliance with NACE MR0175 / ISO 15156 sour service standard is mandatory.

Industry Applications

Inconel 601 Applications

Heat Treating Equipment: Retorts, muffles, wire mesh belts, and furnace hearths.

Petrochemical Processing: Catalyst regenerators and process heaters.

Power Generation: Superheater tube supports and ash handling components.

Inconel 625 Applications

Offshore & Marine: Subsea flowlines, riser clamps, valve stems, and marine hardware.

Aerospace & Defense: Jet engine ducting, thrust-reverser systems, and turbine shrouds.

Chemical Industry: Hydrochloric acid production vessels and flue gas desulfurization (FGD) scrubbers.

Manufacturing Standards & Product Supply Range

HT PIPE maintains extensive stock and manufacturing capability for both Alloy 601 and Alloy 625 in all major product forms:

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