NI · superalloy
Nickel-Copper Alloy Monel 400 (UNS N04400)
The most forgiving of the nickel alloys: it machines closer to a tough stainless than to a superalloy, although it work-hardens and galls like its relatives.
Quoting this material
- Typical lead time
- 15–25 working days
- Condition
- Annealed
- Achievable finish
- Ra 1.6 µm typical · Ra 0.4 µm best
Machined in-house to your drawing: see the precision CNC machining service and the machine and inspection capability it runs on.
Machinability
Our own 1–10 shop ranking, not a published index: 10 is free-cutting brass C360, 1 is Inconel 718. It ranks how a material behaves on the floor - cycle time, chip control and tool life together. Where a published index exists it is quoted in the note.
The most forgiving of the nickel alloys: it machines closer to a tough stainless than to a superalloy, although it work-hardens and galls like its relatives.
Properties as supplied
| Parameter | Value | Unit |
|---|---|---|
| Tensile strength | 550 | MPa |
| Yield strength (0.2%) | 240 | MPa |
| Elongation | 40 | % |
| Hardness | ~150 | HB |
| Service temperature | To 480 | °C |
| Thermal conductivity | 21.8 | W/m·K |
Hardness, tensile and thermal figures are typical published values for the condition stated. Actual mill certificates govern; send the specification with the drawing and we confirm against the certificate before the material is cut.
Condition
Annealed
Heat treatment
Not precipitation hardenable; it is a solid-solution nickel-copper alloy. Annealing after cold work or welding restores ductility.
Achievable surface finish
Ra 1.6 µm
Ra 0.4 µm
Finishes well with sharp tooling; the galling tendency means a dull tool tears the surface.
Tooling and cutting parameters
Cutting speed
- 40–80 m/min (carbide)
Feed
- 0.10–0.25 mm/rev turning · 0.06–0.15 mm/tooth milling
Tooling
- Fine-grain carbide, sharp positive rake, generous clearance
Coolant
- High-pressure flood
Starting points for carbide on a rigid setup, not a guarantee. The right numbers depend on the machine, the toolholder and the fixturing - ask and we will say what we would actually run.
Typical applications
- Seawater valves, pumps and fittings
- Hydrofluoric acid handling equipment
- Marine and offshore hardware
- Heat exchanger tubes
- Petrochemical process parts
DFM notes for this grade
- It is copper-nickel, so it machines with a copper-like tendency to gall - a sharp, polished tool is worth more here than a coated one
- It resists seawater and hydrofluoric acid where stainless fails, which is usually the whole reason it is specified
- Not for high-temperature strength: the service limit is around 480 °C, above which it loses its advantage to the superalloys
Questions buyers ask
- How is Monel 400 different from stainless in seawater?
- It does not pit or crevice corrode in flowing seawater, and it does not get attacked by chloride stress corrosion. 316L resists seawater better than carbon steel and still pits in a stagnant crevice; Monel survives in the same service, which is why seawater valves and fittings are made from it.
- Why is Monel easier to machine than Inconel?
- Lower hardness and lower strength at temperature. It is still a nickel alloy with the work-hardening and galling of the family, but it has no carbide structure to abrade the tool and no precipitation-hardening system, so it cuts at double or triple the speed of 718.
Grades we would quote instead
Inconel 600
2/10The mildest of the common nickel alloys to machine - still awkward, but it work-hardens less aggressively than 625 and far less than 718.
C63000 Nickel Aluminium Bronze
4/10The strongest of the standard bronze families: about the cutting speed of a stainless and the tool wear of one too.
Hastelloy C-276
1/10One of the hardest materials in this catalogue: very tough, work-hardening, and abrasive.