Monel® Alloy 400 (UNS N04400)
Monel® Alloy 400 is a high-performance nickel-copper alloy that is widely regarded as the "workhorse" of the marine and chemical industries. It is a solid-solution alloy that can only be hardened by cold working, offering a remarkable combination of high strength and toughness over a wide temperature range. Its defining characteristic is its incredible resistance to rapidly flowing brackish water or seawater, making it the premier choice for naval and subsea engineering.
At Aries Alloys, we supply Monel 400 to manufacturers who require a metal that is virtually immune to chloride-ion stress corrosion cracking. Whether it is for a marine propeller shaft or a chemical storage tank, our Alloy 400 is sourced to provide a lifetime of service in the most aggressive atmospheres.
Core Performance Benefits
- Exceptional Marine Durability: Outstanding resistance to seawater, even under high-velocity conditions, and immunity to cavitation and erosion.
- Aggressive Acid Resistance: Highly resistant to hydrofluoric acid and sulfuric acid in reducing conditions, where many other alloys fail.
- Broad Temperature Range: Maintains its mechanical properties from sub-zero and cryogenic temperatures up to 1000° F (538° C).
- Stress-Corrosion Immunity: Virtually immune to chloride-induced stress corrosion cracking, making it safer than most stainless steels in saline environments.
- Excellent Fabricability: Easily welded using standard gas-arc processes and highly adaptable to machining, forging, and cold-forming.
Technical Profile & Data
The Nickel-Copper Balance:
The alloy is composed primarily of Nickel (minimum 63%) and Copper (28-34%). This specific ratio creates a material that is "nobler" than copper and tougher than pure nickel, providing a balanced defense against both oxidizing and reducing environments.
Mechanical Capabilities:
- Specific Gravity: 8.80
- Magnetic Property: Slightly magnetic at room temperature (Curie point is near ambient).
- High Impact Strength: Does not undergo a ductile-to-brittle transition even at the temperature of liquid hydrogen.
- Thermal Conductivity: Better heat transfer properties than many other high-nickel alloys.
Primary Industry Use Cases
Aries Alloys is a strategic supplier of Monel 400 for critical infrastructure:
- Marine Engineering: Propeller shafts, pump shafts, seawater valves, and splash-zone sheathing for offshore platforms.
- Chemical Processing: Equipment for the production of salt, chlorinated solvents, and the handling of hydrofluoric acid.
- Oil & Gas Extraction: Crude oil distillation towers and heater elements for sour gas environments.
- Power Generation: Boiler feedwater heaters and other heat exchangers in both nuclear and fossil fuel plants.
- Aeronautics: Fuel and oil tanks, as well as specialized fasteners for airframe construction.
Product Availability at Aries Alloys
We stock and supply Monel 400 in formats conforming to ASTM B164, B127, and B165:
- Round & Hex Bars: Precision bars for machining shafts, bolts, and marine hardware.
- Sheets & Plates: Corrosion-resistant flat products for vessel construction and linings.
- Seamless Piping: High-integrity tubes for chemical transport and heat exchangers.
- Forged Fittings: Custom flanges, elbows, and tees designed for harsh fluid environments.