Hangbo Alloy Group
Shanghai · Est. 2012
N04405 technical guide: nominal chemical composition, mechanical and physical properties, corrosion resistance, welding, product forms and ASTM standards...
Monel R-405 (UNS N04405) is a free-machining nickel-copper alloy. Free-machining Monel 400 variant. Same seawater/chemical resistance as 400. 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 R-405 for a project.
Monel R-405 belongs to the free-machining nickel-copper alloy class of materials. It is free-machining monel 400 variant. It is same seawater/chemical resistance as 400. It is not recommended for welded fabrications.
Nominal (wt%) composition of Monel R-405 (UNS N04405):
| Element | Composition (wt%) |
|---|---|
| Nickel (Ni) | 63.0 – 70.0 |
| Copper (Cu) | Balance |
| Sulphur (S) | 0.025 – 0.060 |
| Iron (Fe) | ≤ 2.5 |
| Manganese (Mn) | ≤ 2.0 |
| Silicon (Si) | ≤ 0.50 |
| Aluminium (Al) | ≤ 0.50 |
| Carbon (C) | ≤ 0.15 |
Typical physical properties:
| Property | Value |
|---|---|
| Density | 8.83 g/cm³ |
| Melting Range | 1300 – 1350 °C |
| Thermal Expansion (20–300 °C) | 14.1 µm/m·K |
| Thermal Conductivity (100 °C) | 21.0 W/m·K |
| Electrical Resistivity | 0.51 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) | 240 MPa (35 ksi) |
| Elongation in 50 mm | 35% |
| Hardness (Rockwell B) | 65 – 80 HRB |
| Property | Value |
|---|---|
| Service temperature | Cryogenic to ≈ 450 °C |
R-405 is the free-machining version of Monel 400, with controlled sulphur that forms harmless manganese sulphide inclusions for chip break-up. It keeps the full Monel 400 corrosion profile – excellent resistance to seawater, brackish water, alkaline and non-oxidising acid environments.
The sulphur that aids machining makes R-405 less suitable for welding (hot cracking / porosity). For welded fabrications use Monel 400; R-405 is intended for machined parts.
The grade is supplied to the following common specifications:
| Standard | Product Form / Scope |
|---|---|
| ASTM B164 | Bar, Rod & Wire |
| ASTM B127 | Plate, Sheet & Strip |
| SAE / AMS references | Machining stock |
R-405 is the free-machining grade of Monel 400. Controlled sulphur (0.025–0.060 %) creates inclusions that break chips, giving excellent machinability while keeping Monel's corrosion resistance.
It is not recommended for welding – the sulphur raises hot-cracking and porosity risk. For welded assemblies use Monel 400; reserve R-405 for machined parts.
Annealed: ≈ 515 MPa tensile, ≈ 240 MPa yield, 35 % elongation, 65–80 HRB – essentially the Monel 400 profile.
High-volume machined products: valve and pump parts, fasteners, marine hardware and automatic-screw-machine components where corrosion resistance and machinability both matter.
Chemically almost identical except for the intentional sulphur addition for machining. 400 is the general/weldable grade; R-405 is the machining specialist.
Bar/rod/wire ASTM B164 and plate/sheet/strip ASTM B127, with machining stock referenced by SAE/AMS documents.
As a dedicated nickel alloy manufacturer serving marine, oil & gas, chemical processing 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.