Specifications
Surface Treatments
Certifications
- ISO 9001 - 2015 Certified
- PED 2014/68/EC
- NACE MR0175/ISO 15156-2
- NORSOK M-650
- DFAR
- MERKBLATT AD 2000 W2/W7/W10
Nickel-Copper Alloy Family - Monel 400, R-405, K-500 & Cupronickel
The nickel-copper alloy family (Ni-Cu alloy, Monel family, copper-nickel alloy, cupronickel) groups wrought metals built on the continuous Ni-Cu solid solution. Monel® 400 (UNS N04400) is the flagship at the nickel-rich end; Monel R-405 (UNS N04405) is the free-machining sister grade; Monel K-500 (UNS N05500) is the age-hardened high-strength variant. Cupronickel 90/10 (UNS C70600) and 70/30 (UNS C71500) dominate the copper-rich seawater piping band; Constantan (UNS C72150) at 55 Cu 45 Ni is the resistance grade. Monel is a registered trademark of Special Metals Corporation; TorqBolt is not authorized by, affiliated with or endorsed by Special Metals.
Composition Spectrum of the Ni-Cu Family
Nickel and copper are fully miscible at every ratio, so the family spans a continuous chemistry band. Monel 400 dominates the nickel-rich corner at 67 Ni 31 Cu; the 50/50 region is the resistance-alloy band; the copper-rich corner is the cupronickel piping band.
| Position | Grade | UNS | Nominal Ni | Nominal Cu | Primary use |
|---|---|---|---|---|---|
| Nickel-rich | Monel 400 | N04400 | 63 - 70 | 28 - 34 | HF acid, seawater, fasteners |
| Nickel-rich | Monel R-405 | N04405 | 63 - 70 | 28 - 34 | Free-machining shafts, screw stock |
| Nickel-rich, age-hard | Monel K-500 | N05500 | 63 - 70 | balance | Pump shafts, valve trim, downhole bolting |
| 50/50 resistance | Constantan | C72150 | 43 - 47 | 53 - 57 | Thermocouple wire, strain gauge foil |
| Copper-rich | Cupronickel 70/30 | C71500 | 29 - 33 | balance | Seawater piping, condenser tube |
| Copper-rich | Cupronickel 90/10 | C70600 | 9 - 11 | balance | Shipboard piping, heat exchanger tube |
Monel 400 (UNS N04400) - The Flagship Ni-Cu Alloy
Monel 400 is the workhorse of the family and the reason the trademark name became generic shorthand for nickel-copper alloy. Chemistry is single across wrought forms at 63 to 70 percent nickel and 28 to 34 percent copper, with iron 2.5 max, manganese 2.0 max, carbon 0.30 max, silicon 0.50 max and sulphur 0.024 max. Coverage spans ASTM B127 (plate), B164 (bar, wire), B165 (pipe), B564 (forgings), F467 (nuts) and F468 (bolts). DIN registers the same window as DIN 17743 NiCu30Fe, Werkstoff 2.4360. Full element data on chemical composition; UNS entry at UNS N04400. Default Ni-Cu grade for HF acid alkylation, seawater, brine and hot caustic.
Monel R-405 (UNS N04405) - Free-Machining Variant
Monel R-405 shares the Ni-Cu bracket of Monel 400 but raises sulphur to 0.025 to 0.060 percent. The added sulphur forms MnS chip breakers that lift feed rates and cut tool wear on screw machines and CNC turning of shafts and small fasteners. R-405 is not weldable. Coverage is ASTM B164 Class A. For speeds and tool geometry see machinability.
Monel K-500 (UNS N05500) - Precipitation-Hardened High Strength
Monel K-500 takes the Monel 400 corrosion envelope and adds yield strength via aluminium 2.30 to 3.15 percent and titanium 0.35 to 0.85 percent. After solution anneal and age, a gamma-prime Ni3(Al,Ti) phase lifts yield to 90 to 130 ksi against 40 to 50 ksi for Monel 400. Coverage is ASTM B865 and F467 / F468. Typical service: oilfield bolting, pump shafts, valve trim, propeller shafts. NACE MR0175 caps hardness at 35 HRC for sour service. Full data on Monel 400 vs Monel K-500.
Cupronickel 90/10 and 70/30 - Copper-Rich Seawater Piping
Cupronickel 90/10 (UNS C70600) at 88-90 Cu 10 Ni 1.5 Fe 1.0 Mn is the lowest-nickel grade for seawater service. Cupronickel 70/30 (UNS C71500) at 68-70 Cu 30-32 Ni carries higher strength and velocity allowance. Coverage is ASTM B466 / B467 (pipe), B171 (plate) and B111 (condenser tube). A Cu2O passive film stabilised by nickel and iron resists biofouling and chloride pitting. Cupronickel sits below Monel 400 on cost per kg but is restricted to chloride water at moderate temperature, with no oxidising acids or HF.
Constantan and Resistance Alloys
Constantan (UNS C72150) at 55 Cu 45 Ni is the point where electrical resistivity peaks near 49 microohm-cm and the temperature coefficient approaches zero. Wrought forms are wire and foil per ASTM B267 and ASTM E230. Constantan is the negative leg of type T and type E thermocouples, the standard for foil strain gauges, and the element in precision shunts. Cu-Ni 10, 20 and 30 cover resistor and heater applications.
| Service condition | First-choice Ni-Cu grade |
|---|---|
| HF acid alkylation, hot caustic, brine | Monel 400 (N04400) |
| Sour service NACE MR0175 (to 35 HRC) | Monel 400 or Monel K-500 |
| High-strength downhole / topside fasteners | Monel K-500 (N05500) |
| Free-machining shafts, screw stock (unwelded) | Monel R-405 (N04405) |
| Seawater condenser tube, shipboard piping | Cupronickel 90/10 (C70600) |
| High-velocity or sulphide-bearing seawater | Cupronickel 70/30 (C71500) |
| Thermocouple wire, strain gauge foil | Constantan (C72150) |
Frequently Asked Questions
What is the nickel-copper alloy family? Wrought metals built on the continuous Ni-Cu solid solution. Monel 400 anchors the nickel-rich end at 67/31, Constantan sits at 55/45, and Cupronickel 70/30 and 90/10 occupy the copper-rich end for seawater piping.
Monel 400 vs Cupronickel? Monel 400 at 40 to 50 ksi yield clears Cupronickel 90/10 (15 ksi) and 70/30 (20 ksi), and carries a broader corrosion envelope. Cupronickel is the lower-cost option for moderate-temperature seawater piping only.
When use K-500? When yield above 90 ksi is required and the Monel 400 corrosion envelope must be retained: oilfield bolting, pump shafts, valve trim, propeller shafts. NACE MR0175 caps K-500 hardness at 35 HRC.
Is R-405 weldable? No. The 0.025 to 0.060 sulphur that gives R-405 its free-machining property prevents fusion welding. Specify Monel 400 for parts welded after machining.
Related Pages and Request a Quote
Reference: UNS N04400, chemical composition, machinability, vs Monel K-500, HF acid resistance, marine applications, NACE MR0175.
For any nickel-copper alloy grade against a specific ASTM B127, B164, B165, B564, F467 or F468 chemistry brief, send drawing, quantity and certification class (EN 10204 type 3.1 or 3.2) to info@torqbolt.com or WhatsApp +91-22-66157017. Ex-Mumbai price plus heat-numbered MTC inside one working day. Domestic India 3 to 7 working days; export through JNPT.
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