Monel R405 Product Introduction
Product Overview
Monel R405 (UNS N04405) is a free-machining variant of Monel 400, engineered to enhance machinability while retaining most of Monel 400’s iconic nickel-copper (Ni-Cu) corrosion resistance. Unlike the general-purpose Monel 400 (poor machinability) or strength-optimized Monel K500 (precipitation-hardened), Monel R405 incorporates controlled sulfur (S: 0.024-0.060%)—a key additive that forms microscale sulfide inclusions (e.g., NiS, CuS) to reduce cutting tool wear and improve chip breakability. This modification boosts machining efficiency by 20-30% vs. Monel 400, while maintaining resistance to seawater, brine, and dilute acids. It performs stably up to 427°C and is ideal for precision-machined components (e.g., instrument parts, small fasteners) where “corrosion resistance + high machining productivity” are critical—filling the gap between non-machinable 耐蚀 alloys and low-corrosion free-machining steels.
International Grade Comparison
Standard System | Grade | Description |
ASTM (USA) | N04405 | UNS Unified Numbering System Grade (exclusive for Monel R405) |
EN (EU) | NiCu30FeS | EN 10088-1 Standard Grade (free-machining Ni-Cu alloy) |
JIS (Japan) | NW04405 | JIS G4902 Standard Grade (equivalent to Monel R405) |
DIN (Germany) | 2.4361 | DIN 17750 Standard Grade (free-machining variant of Monel 400’s 2.4360) |
ISO (International) | NiCu30FeS | ISO 6363 Standard Grade (machinability & corrosion dual-optimized Ni-Cu alloy) |
Physical Properties (Room Temperature & Machinability Highlights)
Property Indicator | Typical Value (Room Temp) | Unit | Performance Advantage |
Tensile Strength | ≥450 | MPa | Slightly lower than Monel 400 (≥485 MPa) but sufficient for precision parts |
Yield Strength (0.2% Offset) | ≥160 | MPa | Close to Monel 400; meets general structural load requirements |
Elongation (50mm Gauge Length) | ≥25 | % | Lower than Monel 400 (≥35%) but retains ductility for forming |
Density | 8.88 | g/cm³ | Nearly identical to Monel 400 (8.89 g/cm³) |
Melting Point | 1300-1350 | ℃ | Stable up to maximum service temperature (427°C) |
Machinability Index | 70-80 (vs. Monel 400: 50) | — | Cutting speed 20-30% higher than Monel 400; better chip control |
Magnetic Property | Non-magnetic | — | Suitable for electronic/instrument components |
Chemical Composition (Mass Fraction, Key Elements & Machinability Mechanism)
Chemical Symbol | Composition Range (%) | Role in Performance |
Ni | 63.0-70.0 (Balance) | Stabilizes austenitic matrix; retains Monel 400’s corrosion resistance |
Cu | 28.0-34.0 | Enhances seawater/brine resistance; balances sulfide inclusion formation |
S | 0.024-0.060 | Core free-machining additive; forms soft sulfide inclusions to reduce tool wear |
Fe | ≤2.5 | Improves hot workability; reduces hot cracking during forging |
Mn | ≤2.0 | Refines sulfide inclusions (prevents large, brittle inclusions); improves toughness |
C | ≤0.3 | Minimizes carbide precipitation; avoids intergranular corrosion |
Si | ≤0.5 | Improves weldability; reduces welding defects (for machined-welded parts) |
Product Characteristics
1.Superior Free-Machining Performance: Sulfide inclusions (NiS/CuS) act as “internal lubricants” during cutting, reducing tool wear by 30-40% vs. Monel 400; chips break easily, enabling high-speed machining (up to 150 m/min) and excellent surface finish (Ra ≤1.6 μm);
2.Retained Corrosion Resistance: Maintains 90% of Monel 400’s resistance to seawater, brine, and dilute acids (e.g., 20% sulfuric acid at room temp); sulfide inclusions do not trigger pitting or crevice corrosion in non-extreme environments;
3.Balanced Mechanical Properties: Tensile strength (≥450 MPa) and ductility (≥25% elongation) meet requirements for precision structural parts (e.g., valves, fasteners); no significant strength loss up to 427°C;
4.Cost-Effective Processing: Faster machining speed + longer tool life reduce production costs by 15-20% vs. Monel 400; eliminates post-machining grinding for most parts;
5.Limitations Note: Not recommended for high-stress (≥300 MPa load) or high-temperature (＞427°C) applications—sulfide inclusions may slightly reduce fatigue strength and creep resistance.
Metallographic Structure
At room temperature, Monel R405 features a single-phase face-centered cubic (FCC) austenitic matrix (same as Monel 400) with uniformly dispersed fine sulfide inclusions (0.5-2 μm in size, primarily NiS and CuS). These inclusions are soft, ductile, and evenly distributed along grain boundaries and within grains—they do not disrupt the austenitic matrix stability but create “shear planes” during cutting, enabling easy chip separation and reducing tool friction. No harmful intermetallic phases (e.g., sigma phase) form even after long-term exposure to 427°C.
Product Forms and Executive Standards
Product Form | Main International Executive Standards | Application Reference |
Bars (Primary Form) | ASTM B160, EN 10088-2 | Precision machined parts (valve cores, instrument shafts, small fasteners) |
Wires/Rods | ASTM B164, EN 10250-3 | Small-diameter components (electronic connectors, medical device pins) |
Forgings | ASTM B160, EN 10269 | Near-net-shape parts (pump impellers, gear blanks) requiring post-machining |
Sheets (Limited) | ASTM B127, EN 10088-2 | Thin-walled machined parts (chemical instrument housings) |
