Product introduction

Incoloy is a representative brand of Ni-Cr-Fe-based high-temperature alloys. Its core design concept is to maintain excellent mechanical properties and stability in harsh environments such as high temperature, corrosion, and oxidation. It is different from the Ni-Cu-based Monel alloy and also different from the Inconel alloy with a higher Ni content (usually >70%). The Ni content of Incoloy is usually 30%-50%, and the Fe content accounts for a higher proportion (20%-50%), combining cost advantages and comprehensive performance.

Core features

1.High-Temperature Resistance

The high chromium content enables the alloy to rapidly form a dense chromium oxide film in high-temperature oxidizing environments, inhibiting the reaction between oxidants and the base metal and allowing it to withstand repeated heating. For example, the oxide film of Incoloy 800H is not easily flaked off at operating temperatures below 816°C.

2.Corrosion Resistance

Incoloy alloy plates exhibit excellent corrosion resistance to a variety of corrosive media. For example, Incoloy 800 exhibits significantly better stress corrosion resistance than 18-8 stainless steel and Inconel 600 in certain high-temperature, high-pressure aqueous media. Incoloy 825 exhibits excellent corrosion resistance in both reducing and oxidizing acids, with exceptional resistance to sulfuric and phosphoric acids.

3.Mechanical Properties

Incoloy alloy sheets maintain stable mechanical properties at both room and elevated temperatures. For example, Incoloy 800H has a minimum tensile strength of 450 N/mm², a minimum yield strength of 180 N/mm², and an elongation of 35% at room temperature. Furthermore, it exhibits excellent creep resistance and durability even in elevated temperature environments.

Grade

Production process

1. Vacuum Melting: Using a combined process of vacuum induction melting (VIM) and vacuum arc remelting (VAR) or electroslag remelting (ESR), the ingot is precisely controlled to remove gases (such as N₂, O₂, and H₂) and inclusions, ensuring ingot purity.

2. Hot Forging/Hot Rolling: The ingot is heated to 1100-1200°C and processed into thick slabs through forging or rolling. This breaks down the coarse grains in the cast structure, refines the grains, and improves strength.

3. Cold Rolling: The thick slab undergoes multiple cold rolling passes (at room temperature or low temperature) with controlled reduction (typically 5%-20% per pass) until it is finally rolled to the target thickness (ranging from a few millimeters to tens of millimeters), while also strengthening the plate's hardness.

4. Heat Treatment: Annealing (e.g., 800H requires solution annealing at 1150°C) and age hardening (e.g., 925 requires aging at 700°C) are performed according to the grade requirements to relieve cold rolling internal stresses, adjust the microstructure (e.g., form γ' phase reinforcement), and optimize mechanical properties.

5. Finishing and Inspection: Straightening and cutting are performed to remove defects, followed by non-destructive testing (UT ultrasonic, MT magnetic particle), chemical composition analysis, and mechanical property testing (tensile and impact) to ensure compliance with industry standards (e.g., ASTM B409 and ASME SB409).

Application areas

1. Petrochemical Industry: Hydrogenation reactor liners, sour oil and gas pipelines, and sulfuric acid concentration tower components (825 is preferred).

2. Energy and Power: Nuclear power plant steam generator heat transfer tubes, gas turbine combustion chamber liners, and high-temperature boiler superheater tubes (800H is preferred).

3. Metallurgy and Mining: Acid-resistant tanks and electrolytic cell electrode frames in non-ferrous metal smelting (825 is preferred).

4. Marine Engineering: Heat exchange plates for seawater desalination equipment and corrosion-resistant structural components for offshore platforms (825 is preferred).

5. Aerospace: High-temperature aircraft engine accessories and spacecraft propulsion system piping (precipitation-hardened 925 is preferred).