Monel400 Alloy

I. Overview

Monel400 is a nickel-copper-based corrosion-resistant alloy developed by the International Nickel Company (INCO) in the early 20th century. Renowned for its outstanding corrosion resistance and balanced mechanical properties, it has become a critical material in industrial applications. It forms a high-strength single-phase solid solution structure with a nickel content of approximately 63–70% and a copper content of 28–34%, supplemented by trace elements like iron, manganese, and carbon. This alloy combines copper's ductility with nickel's passivation properties, excelling in extreme environments such as hydrofluoric acid, seawater, and high-temperature alkaline solutions. Its resistance to stress corrosion cracking has earned it the reputation of a "universal corrosion-resistant alloy".

II. International and Domestic Designations

Monel400 is standardized under various global specifications:

· ​United States: UNS N04400 (ASTM B127/B164/B165)

· ​Germany: W.Nr.2.4360 (DIN)

· ​China: NCu30 (GB/T, formerly designated as MCu-28-1.5-1.8)

· ​Japan: NW4400 (JIS)

· ​Common Names: Monel 400, Alloy 400.

III. Key Chemical Composition

Monel400’s composition (by weight percentage) is dominated by nickel and copper:

· ​Nickel (Ni): 63.0–70.0% (primary contributor to corrosion resistance)

· ​Copper (Cu): 28.0–34.0% (enhances ductility)

· ​Iron (Fe): ≤2.5%

· ​Manganese (Mn): ≤2.0%

· ​Carbon (C): ≤0.3%

· ​Silicon (Si): ≤0.5%

· ​Sulfur (S): ≤0.024%.

IV. Core Characteristics

1. ​Corrosion Resistance​

· ​Acidic Media: Resists hydrofluoric acid (up to boiling point), hydrochloric acid (concentration <85% sulfuric acid), fluorine gas, and derivatives.

· ​Alkaline Media: Withstands hot concentrated alkalis (e.g., NaOH), though stress corrosion cracking may occur under high-temperature stress.

· ​Marine Environments: Corrosion rate in seawater is <0.025 mm/a, outperforming copper-based alloys.

· ​Special Media: Resists chlorides, sulfides, organic compounds, and ammonia (≤585°C).

2. ​Mechanical Properties​

· Tensile Strength: 450–880 MPa

· Yield Strength: 170–520 MPa

· Elongation: ≥30% (annealed state)

· High-Temperature Stability: Maintains strength below 538°C; excellent low-temperature toughness (down to liquid hydrogen temperatures).

3. ​Manufacturability​

· Suitable for cold/hot working (forging, rolling, drawing) and welding (TIG, MIG, arc welding).

· Machining requires attention to shrinkage allowance; water-based coolants are recommended for high-speed operations.

V. Major Applications

1. ​Marine Engineering​

· Desalination equipment, ship propeller shafts, submarine pipelines, and offshore platform components.

2. ​Chemical & Petroleum Industries​

· Sulfuric/hydrochloric acid reactors, distillation towers, oil/gas pipelines, and refinery linings.

3. ​Aerospace​

· High-temperature engine components, fuel system parts, and spacecraft structures.

4. ​Nuclear & Power Generation​

· Nuclear fuel processing equipment, boiler feedwater heaters, and heat exchangers.

5. ​Other Fields​

· Pharmaceutical equipment (corrosion-resistant sanitary standards), environmental engineering (wastewater treatment), and electronics.

VI. Development & Market Trends

Since its commercialization in the early 20th century, Monel400 has undergone continuous optimization (e.g., vacuum melting, age hardening). Recent demand growth is driven by marine exploration and renewable energy sectors. Global supply chains increasingly emphasize localized production to support customized processing and rapid delivery.

Toko Tech, as a leading supplier of piping products, is committed to providing our customers with high-performance and durable solutions. Monel 400 alloy is ideal for extreme environments due to its excellent corrosion resistance, high strength, and excellent resistance to high temperatures. The combination of our piping products and Monel 400 not only meets the needs of high-end fields such as offshore engineering, the chemical industry, and oil and gas but also highlights our relentless pursuit of quality and innovation. In the future, we will continue to rely on advanced materials and technologies to provide our customers with more reliable and efficient piping system solutions, help the industry develop sustainably, and work together to meet the more challenging industrial environment.