Hangbo Alloy Group
Shanghai · Est. 2012
N04404 technical guide: nominal chemical composition, mechanical and physical properties, corrosion resistance, welding, product forms and ASTM standards...
Monel 404 (UNS N04404) is a nickel-copper alloy. Very low Al/Ti for clean glass-to-metal seals. Monel-family seawater & chemical resistance. This guide covers its nominal chemical composition, typical mechanical and physical properties, corrosion behaviour, welding, common applications, available product forms and the ASTM standards that apply — everything a specifier needs to evaluate Monel 404 for a project.
Monel 404 belongs to the nickel-copper alloy class of materials. It is very low al/ti for clean glass-to-metal seals. It is monel-family seawater & chemical resistance. It is low magnetic permeability.
Nominal (wt%) composition of Monel 404 (UNS N04404):
| Element | Composition (wt%) |
|---|---|
| Nickel (Ni) | 52.0 – 57.0 |
| Copper (Cu) | Balance |
| Aluminium (Al) | ≤ 0.05 |
| Titanium (Ti) | ≤ 0.10 |
| Iron (Fe) | ≤ 0.50 |
| Manganese (Mn) | ≤ 0.10 |
| Silicon (Si) | ≤ 0.10 |
| Carbon (C) | ≤ 0.15 |
| Sulphur (S) | ≤ 0.024 |
Typical physical properties:
| Property | Value |
|---|---|
| Density | 8.64 g/cm³ |
| Melting Range | 1300 – 1350 °C |
| Thermal Expansion (20–300 °C) | 14.0 µm/m·K |
| Thermal Conductivity (100 °C) | 21.0 W/m·K |
| Electrical Resistivity | 0.52 µΩ·m |
| Modulus of Elasticity | 180 GPa |
Typical room-temperature mechanical properties (annealed / specified condition unless noted):
| Property | Typical Value |
|---|---|
| Tensile Strength (Rm) | 515 MPa (75 ksi) |
| Yield Strength, 0.2% (Rp0.2) | 205 MPa (30 ksi) |
| Elongation in 50 mm | 40% |
| Hardness (Rockwell B) | 60 – 75 HRB |
| Property | Value |
|---|---|
| Service temperature | Cryogenic to ≈ 450 °C |
404 is a controlled-composition Monel with very low aluminium and titanium so it does not form brittle intermetallics during glass sealing. It keeps the general seawater and chemical resistance of the Monel family and is chosen specifically for hermetic glass-to-metal seals.
Welded by GTAW/GMAW with matching ERNiCu-7 filler, but for glass-seal parts welding is minimised. Keep heat input low to preserve the fine, inclusion-free microstructure needed for sealing.
The grade is supplied to the following common specifications:
| Standard | Product Form / Scope |
|---|---|
| ASTM B164 | Bar, Rod & Wire |
| ASTM B127 | Plate, Sheet & Strip |
| AMS 7233 | Wire for seals |
404 is a nickel-copper alloy with specially low aluminium and titanium (≤ 0.05 and ≤ 0.10 %) so it avoids brittle intermetallics during glass sealing. It keeps Monel's seawater/chemical resistance and is used for hermetic glass-to-metal seals.
Aluminium and titanium form oxide/intermetallic films that ruin the wetting and bond between metal and molten glass. Keeping them very low gives the clean, reproducible seals needed in electronics packaging.
Annealed: ≈ 515 MPa tensile, ≈ 205 MPa yield, 40 % elongation, 60–75 HRB.
Yes – like other Monels it resists seawater, brackish water and many non-oxidising acids, which is why it is also used for marine and cryogenic seals.
With ERNiCu-7 filler by GTAW/GMAW, but glass-seal parts are usually fabricated with minimal welding and low heat input to protect the sealing microstructure.
Bar/rod/wire ASTM B164, plate/sheet/strip ASTM B127, with seal wire referenced under AMS 7233.
As a dedicated nickel alloy manufacturer serving aerospace, power generation, marine sectors, Hangbo Alloy Group supplies the grades discussed here across all standard product forms with full ASTM/ASME documentation and EN 10204 3.1 certification. Our material is specified for applications where corrosion resistance, high-temperature strength, and traceable quality are non-negotiable. See our production & testing facilities for more on how every heat is verified.