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| UNS Number | N04400 |
| ASTM/ASME Standard | ASTM B164 / ASME SB164 |
| Tensile Strength | 550-690 MPa |
| Yield Strength | 240-345 MPa |
| Density | 8.80 g/cm³ |
| Max Service Temperature | 425°C |
| Element | Composition (%) |
|---|---|
| Ni | 63.0–70.0 |
| Cu | 28.0–34.0 |
| Fe | ≤2.5 |
| Mn | ≤2.0 |
| C | ≤0.30 |
| Si | ≤0.50 |
| S | ≤0.024 |
Monel 400 fasteners derive their properties from a nickel-copper alloy composition, typically containing 63-70% nickel and 28-34% copper, with small additions of iron, manganese, carbon and silicon. The high nickel content provides exceptional resistance to alkalis and reducing environments, while the copper addition enhances resistance to hydrofluoric acid and seawater corrosion. Iron and manganese contribute to improved mechanical strength and hot-working characteristics, ensuring the alloy maintains structural integrity during fastener manufacturing processes such as forging and thread rolling.
This carefully balanced composition delivers outstanding corrosion resistance across marine, chemical processing and oil and gas environments, making Monel 400 fasteners ideal for demanding applications. The alloy retains good mechanical properties from sub-zero temperatures up to 425°C, offering excellent strength without embrittlement. Its inherent resistance to stress corrosion cracking, combined with non-magnetic properties and good weldability, makes it a preferred choice for critical bolting applications in seawater systems, chemical plants and offshore platforms where reliability and longevity are essential.
Specifications
Monel 400 Fasteners are specified by nickel-copper alloy composition, mechanical strength, corrosion resistance, and precise dimensional tolerances, with technical data covering sizes, thread profiles, and load capacity for demanding service, aligned with applicable industry standards. Their performance and geometry define reliable use in marine and chemical applications.
| Property | Value |
|---|---|
| Tensile Strength | 550-690 MPa |
| Yield Strength (0.2% offset) | 240-345 MPa |
| Elongation | 35-40% |
| Hardness | 110-150 HB |
| Modulus of Elasticity | 179 GPa |
| Thermal Expansion (20-100°C) | 13.9 µm/m·°C |
| Thermal Conductivity | 21.8 W/m·K |
| Density | 8.80 g/cm³ |
| Melting Range | 1300-1350°C |
| Maximum Service Temperature | 425°C |
| Standard/Parameter | Details |
|---|---|
| Bolt Standard | ASTM A193/A194, DIN 931/933 |
| Stud Bolt Standard | ASTM A193 Gr B164 |
| Nut Standard | ASTM A194, DIN 934 |
| Washer Standard | ASME B18.22.1, DIN 125 |
| Thread Form | UNC, UNF, Metric Coarse/Fine |
| Diameter Range | M6 to M100 / 1/4" to 4" |
| Length Range | 10mm to 500mm |
| Available Product Forms | Hex Bolts, Studs, Nuts, Washers |
| Custom Sizes | Available on request |
| Inspection Standards | NACE MR0175, EN 10204 3.1 |
Applications
Monel 400 bolts, nuts and studs are widely used on seawater piping, pumps, valves, heat exchangers, splash-zone structures and shipboard equipment. The alloy resists flowing seawater and brine better than many stainless steels, helping reduce galling, crevice corrosion and premature fastener replacement.
Alloy 400 fasteners are selected for process vessels, evaporators, transfer lines and acid-handling equipment exposed to hydrofluoric acid, neutral and alkaline salts, caustic soda and reducing media. Their nickel-copper chemistry provides dependable corrosion resistance without relying on high chromium content.
Monel 400 studs and nuts are used in refinery, offshore and gas-processing assemblies where chloride-bearing environments, produced water and non-oxidizing media are present. Correct material certification, heat condition and coating selection should be matched to project specifications and service severity.
Monel 400 fasteners are suitable for desalination plants, brine heaters, feedwater equipment and heat exchanger assemblies. The alloy maintains toughness at low temperature and offers stable mechanical performance across a broad operating range, making it useful for both maintenance and new-build critical bolting.
