Alloy N,UNS N10003—Hastelloy N Nickel-Based High Temperature Corrosion Resistant Alloy

Alloy N, designated UNS N10003 and commonly referred to as Hastelloy N, is a classic nickel-based solution-strengthened superalloy engineered for high-temperature fluoride salt, strongly acidic corrosion and high-temperature service conditions. With a multi-element formulation of nickel, molybdenum and chromium, it combines excellent high-temperature strength, creep resistance and broad-spectrum corrosion resistance, enabling long-term stable operation under extreme conditions such as ultra-high temperatures, severe corrosion and alternating loads. It is widely used in high-end industrial sectors including nuclear energy, fine chemicals, high-temperature smelting and environmental desulfurization, making it an optimal material for high-temperature molten salt and reductive corrosion environments.

1、Chemical Composition

2、Typical Physical and Mechanical Properties (RT, Annealed)

3、Core Advantages

3.1 High Resistance to High-Temperature Fluoride Salt and Acid-Alkali Corrosion

The high addition of molybdenum gives ALLOY N (UNS N10003) an extremely low corrosion rate in high-temperature molten fluoride salt environments at 704℃ to 871℃, making it one of the best-performing commercial alloys for molten salt corrosion resistance. In addition, the high-nickel matrix combined with the molybdenum-chromium composite system adapts to both reductive and weakly oxidizing media, delivering excellent resistance to concentrated hydrochloric acid, mixed acids, acidic flue gas and chloride solutions, as well as protection against pitting corrosion, crevice corrosion and intergranular corrosion. Its low-carbon design effectively reduces carbide precipitation, further avoiding the risk of corrosion failure.

3.2 Outstanding High-Temperature Oxidation Resistance

With chromium forming a dense oxide protective film on the alloy surface, ALLOY N (UNS N10003) can withstand short-term temperatures up to 1175℃ in air and provide continuous service below 900℃. It features a slow oxidation rate at high temperatures, and will not suffer from surface peeling or performance degradation after long-term high-temperature exposure.

3.3 Excellent High-Temperature Mechanical Properties

ALLOY N (UNS N10003) maintains high tensile strength, creep resistance and thermal fatigue performance at temperatures above 540℃. It can withstand both high temperatures and complex mechanical stress without easy deformation or cracking, making it suitable for high-temperature pressure-bearing and rotating components.

4. Heat Treatment Process

Solution annealing is the core heat treatment method for Alloy N (UNS N10003). During the whole process, long-term holding in the sensitive temperature range of 550℃ to 800℃ shall be avoided to prevent precipitation of harmful phases that would impair material properties. For solution treatment, heat the workpiece to 1150℃ to 1175℃, hold for a period determined by workpiece thickness (1 hour for standard workpieces), followed by rapid water quenching. This process produces a complete single-phase austenite structure, maximizing corrosion resistance, plasticity and comprehensive mechanical properties to lay a foundation for subsequent processing and service. The suitable temperature range for hot working such as forging and rolling is 950℃ to 1200℃. After hot working, supplementary solution treatment is recommended to restore the original properties of the material.

5. Welding Process Requirements

Alloy N features excellent weldability and a wide process window, making it one of the high-temperature corrosion-resistant alloys with strong welding adaptability. Gas Tungsten Arc Welding (GTAW/TIG) is the preferred welding method, and electron beam welding is applicable for critical structural components. High heat input manual arc welding is not recommended to reduce the impact of excessive heat input.

6. Typical Application Fields

With its comprehensive properties of high temperature resistance, molten salt resistance, strong acid resistance and high strength, Alloy N (UNS N10003) serves various high-end harsh working conditions, with core application scopes as follows:

1. Nuclear Power Industry (Core Application) Core vessels, main circulation pipelines, heat exchangers and fuel processing components of Molten Salt Reactors (MSR), compatible with thorium-based molten salt fuel systems, serving as a core material for fourth-generation nuclear power.
2. Fine Chemical and Acid Treatment Industry Hydrochloric acid regeneration units, high-purity hydrochloric acid production and storage equipment, wet-process phosphoric acid reactors, titanium dioxide waste acid treatment systems, as well as pipelines, pumps and valves for chlorine-containing acidic media.
3. High-Temperature Smelting and Thermal Energy Equipment Ethylene cracking furnace tubes, synthetic ammonia reactor linings, high-temperature flue gas incineration pipelines, and high-temperature heat exchange tubes for supercritical boilers, withstanding high temperature, carburization and sulfur corrosion conditions.
4. Environmental Protection and Hydrometallurgy Flue gas desulfurization units, acidic waste gas recovery equipment, and non-ferrous metal wet extraction reactors, resisting corrosion from mixed acids and chlorides.
5. Aerospace and High-End Equipment Structural parts for high-temperature sections of aero-engines, high-temperature heat treatment tooling, and high-temperature high-pressure valves, suitable for environments with high-temperature alternating stress.

C&N supplies Alloy N (UNS N10003) products in a wide range of specifications, including bars, plates, pipes, forgings and custom pipe fittings. All products are subject to strict full-process quality control, with chemical composition and all properties complying with standard specifications, and complete material test reports can be provided for each batch. Please contact us immediately if you have any inquiries or requirements.