⚡ Quick Specs: Monel R-405
What Is Monel R-405?
Monel R-405 (UNS N04405 / W.Nr. 2.4361) is the free-machining variant of Monel 400, featuring a controlled sulfur addition (0.025–0.060%) that dramatically enhances machinability without compromising the legendary corrosion resistance of the Monel family. Designed specifically for automated screw machine and CNC production of fasteners, valve components, and marine hardware, it delivers the same excellent resistance to seawater, hydrofluoric acid, and caustic environments as Monel 400 — but with 30–50% improved machinability. As a trusted Monel R-405 supplier, Hangbo Alloy Group provides this alloy in bar, rod, and wire forms.
Chemical Composition
The nominal chemical composition of Monel R-405 is shown below. All values are in weight percent (wt%) unless otherwise noted.
| Element | Content (wt%) |
|---|---|
| Ni+Co | ≥ 63.0 |
| Cu | 28.0–34.0 |
| Fe | ≤ 2.5 |
| Mn | ≤ 2.0 |
| C | ≤ 0.3 |
| Si | ≤ 0.5 |
| S | 0.025–0.060 |
Physical Properties
| Property | Value |
|---|---|
| Density | ~8.80 g/cm³ (0.318 lb/in³) |
| Melting Range | 1300–1350 °C (2370–2460 °F) |
| Curie Temperature (Magnetic) | ~28 °C (paramagnetic at room temp) |
| Thermal Conductivity | ~21.8 W/m·K (at 20°C) |
| Electrical Resistivity | ~0.547 µΩ·m (at 20°C) |
| Young's Modulus | ~179 GPa |
| Thermal Expansion (20–100°C) | ~13.7 µm/m·°C |
Mechanical Properties (Room Temperature)
| Property | Value |
|---|---|
| Tensile Strength (Rm) | ≥ 480 MPa (70 ksi) — hot-finished |
| Yield Strength (Rp0.2) | ≥ 195 MPa (28 ksi) — hot-finished |
| Elongation (A%) | ≥ 35% |
| Hardness | 60–90 HRB |
| Condition | Hot-finished / Annealed |
Corrosion Resistance — Identical to Monel 400
Monel R-405 maintains the same exceptional corrosion resistance as Monel 400. The added sulfur forms manganese sulfide inclusions that affect only machinability — they do not compromise the alloy's protective passive film in corrosive environments.
- Excellent resistance to seawater and brackish water — immune to chloride stress corrosion cracking
- Outstanding performance in hydrofluoric acid (HF) — one of the few alloys suitable for HF service
- Good resistance to sulfuric acid in non-aerated conditions at moderate concentrations and temperatures
- Resistant to caustic alkalis including sodium hydroxide (NaOH) at all concentrations
- Immune to stress corrosion cracking in chloride environments — a decisive advantage over stainless steels
- Good resistance to neutral and alkaline salt solutions
Applications
Monel R-405 is the go-to material when you need Monel 400's legendary corrosion resistance but in parts that require extensive machining. By increasing the sulfur content to 0.025–0.060%, the alloy forms finely dispersed manganese sulfide inclusions that act as chip breakers, dramatically improving machinability without compromising corrosion performance.
| Application Area | Typical Components & Notes |
|---|---|
| Marine Fasteners & Fittings | Screw-machined bolts, nuts, screws, and threaded fittings for seawater-exposed marine hardware |
| Valve Components | Valve stems, seats, and trim parts requiring both corrosion resistance and precision machining |
| Pump Shafts & Impellers | Machined pump components handling seawater, brackish water, and chemical solutions |
| Instrument Components | Precision-machined parts for pressure gauges, flow meters, and marine instrumentation |
| Oil & Gas Downhole Tools | Screw-machined components for sour gas well completions and subsea equipment |
| Electronic Connectors | Machined electrical connector bodies and contacts requiring corrosion resistance |
| Food Processing Equipment | Machined parts in saline and acidic food processing environments |
Available Product Forms
| Product Form | Typical Dimensions |
|---|---|
| Round Rods & Bars (ASTM B164) | φ3–φ200 mm, Hot-finished, Cold-drawn, Centerless ground |
| Hexagonal Bars | Across-flats 6–50 mm, for screw machine applications |
| Wire (AMS 7234) | φ0.5–φ12 mm, Annealed or Spring-temper |
| Forgings | Custom shapes per customer drawing |
Related Standards & Specifications
| Standard | Product Scope |
|---|---|
| ASTM B164 / ASME SB-164 | Rod, Bar & Wire |
| AMS 4674 | Bars and Forgings |
| AMS 7234 | Wire, Corrosion Resistant |
| QQ-N-281 | Federal Specification — Nickel-Copper Alloy Bar, Rod, Plate, Sheet, Strip, Wire, Forgings, Structural & Special Shaped Sections |
| MIL-N-894 | Military Specification — Nickel-Copper Alloy Bars, Rods, and Forgings |
| NACE MR0175 / ISO 15156 | Sour Service (H₂S containing environments) |
| EN / DIN W.Nr. | 2.4361 |
Frequently Asked Questions (FAQ)
1. What is Monel R-405 alloy?
Monel R-405 (UNS N04405 / W.Nr. 2.4361) is the free-machining grade of Monel 400. It is a nickel-copper alloy with controlled sulfur addition (0.025–0.060%) that dramatically improves machinability by forming chip-breaking manganese sulfide inclusions. Its corrosion resistance and physical properties are essentially identical to Monel 400, making it the preferred choice for components requiring extensive screw machine or CNC machining.
2. What is the chemical composition of Monel R-405?
Monel R-405 composition: Ni+Co ≥63.0%, Cu 28.0–34.0%, Fe ≤2.5%, Mn ≤2.0%, C ≤0.3%, Si ≤0.5%, S 0.025–0.060%. The key difference from Monel 400 is the controlled sulfur addition, which improves machinability by approximately 30–50% compared to standard Monel 400.
3. How does Monel R-405 differ from Monel 400?
The primary difference is machinability. Monel R-405 contains 0.025–0.060% sulfur versus ≤0.024% in Monel 400. This sulfur addition creates finely dispersed manganese sulfide inclusions that improve chip formation and reduce cutting tool wear. The corrosion resistance and physical properties are essentially identical to Monel 400, though mechanical properties have slightly different ranges. R-405 is primarily available in bar and rod forms while Monel 400 is available in all product forms.
4. What is the density and melting point of Monel R-405?
Monel R-405 has a density of approximately 8.80 g/cm³ (0.318 lb/in³) and a melting range of 1300–1350 °C (2370–2460 °F). These values are identical to Monel 400, as the small sulfur addition does not affect bulk physical properties.
5. What are the mechanical properties of Monel R-405?
Typical mechanical properties for hot-finished Monel R-405 bar: tensile strength ≥480 MPa (70 ksi), yield strength (0.2% offset) ≥195 MPa (28 ksi), elongation ≥35%, hardness 60–90 HRB. Properties vary by product form and condition. Cold-drawn bars typically achieve higher strength levels: tensile strength 620–830 MPa, yield strength 415–655 MPa.
6. Can Monel R-405 be welded?
Monel R-405 is NOT recommended for welding. The intentional sulfur addition (0.025–0.060%) can cause hot cracking in the weld fusion zone and heat-affected zone. If welded fabrication is required, use standard Monel 400 instead and perform machining operations after welding. R-405 should be limited to machined-from-bar components.
7. What are typical applications of Monel R-405?
Monel R-405 is used wherever screw machine or CNC-machined parts need Monel 400 corrosion resistance: marine fasteners (bolts, nuts, screws), valve components (stems, seats, trim), pump shafts and impellers, instrument components, oil & gas downhole tool parts, electronic connectors, and food processing equipment components.
8. What is the price and lead time for Monel R-405?
Monel R-405 pricing is similar to Monel 400, typically $25–40/kg for bars, $30–50/kg for wire, depending on size, quantity, and market nickel prices. Lead times: 4–8 weeks for stock sizes, 8–12 weeks for custom specifications. MOQ: 50–100 kg for standard bar sizes. Contact hangbo@nickel-alloy.com for current pricing.
9. What standards apply to Monel R-405?
Key standards: ASTM B164 / ASME SB-164 (rod, bar & wire), AMS 4674 (bars and forgings), AMS 7234 (wire), QQ-N-281 (Federal Specification), MIL-N-894 (Military Specification), and NACE MR0175/ISO 15156 for sour service. The alloy is primarily available in bar, rod, and wire forms.
10. How machinable is Monel R-405 compared to other alloys?
Monel R-405 is approximately 30–50% more machinable than standard Monel 400, qualifying as a free-machining alloy. However, it is still more challenging to machine than free-machining steel (e.g., 12L14) or free-machining brass (e.g., C360). Recommended practices: use carbide tooling, lower cutting speeds (30–50 m/min), generous coolant flow, and rigid setups. For comparison: R-405 machinability rating ~35–45% of free-machining steel (B1112 = 100%).
11. Is Monel R-405 magnetic?
Monel R-405, like Monel 400, is essentially non-magnetic at room temperature and above. The Curie temperature (the point below which the alloy becomes ferromagnetic) is approximately 28 °C (82 °F). At standard ambient and service temperatures, R-405 is paramagnetic with very low magnetic permeability, making it suitable for non-magnetic applications.
12. Can Monel R-405 be used in seawater applications?
Yes, Monel R-405 is extensively used in seawater applications. It offers excellent resistance to flowing seawater (up to 30 m/s flow velocity) and is immune to chloride stress corrosion cracking. However, in stagnant or very low-velocity seawater, it may be susceptible to crevice corrosion and pitting. For critical stagnant seawater applications, consider a duplex stainless steel or titanium. For flowing seawater service, R-405 fasteners and machined components perform exceptionally well.
Need Monel R-405 for Your Project?
Hangbo Alloy Group is a trusted global supplier of Monel R-405 in bars, plates, and custom forms. We provide competitive pricing, full material traceability, and EN 10204 3.1 mill test certificates with every order.