MP35N
A very high-strength Co-Ni-Cr-Mo alloy
Typical values for the temper in the title
MP35N contains about 35% cobalt, about 35% nickel, about 20% chromium and about 10% molybdenum. It strengthens greatly by cold work and aging, to about 1800–2070 MPa tensile, while keeping ductility and high corrosion resistance, including resistance to stress corrosion and hydrogen embrittlement.
Such strength combined with corrosion resistance is rare. It is used for aerospace and marine fasteners, wires and leads in medical devices (ASTM F562), springs and oil and gas components.
Mechanical and physical properties
| Property | Value | Note |
|---|---|---|
| Tensile strength Rm | 1795-2070 MPa (CW+aged) | cold worked and aged |
| Yield strength Rp0.2 | 1480-1795 MPa | cold worked and aged |
| Elongation A | 8-12% | |
| Modulus of elasticity E | 233 GPa | |
| Density ρ | 8.43 g/cm³ | |
| Hardness | about 48–52 HRC (database value) | cold worked and aged |
| Machinability | 20% | relative rating in the site database |
Chemical composition (wt %)
| Element | Range | Role |
|---|---|---|
| Co cobalt | about 35 (nominal) | |
| Ni nickel | about 35 (nominal) | |
| Cr chromium | about 20 (nominal) | corrosion resistance |
| Mo molybdenum | about 10 (nominal) | corrosion resistance and strengthening |
Nominal composition. Exact ranges are in ASTM F562 and AMS specifications.
Conditions and heat treatment
MP35N strengthens by cold work, then by aging.
| Condition | Properties | When to choose it |
|---|---|---|
| Annealed | relatively soft | forming |
| Cold worked and aged | about 1800–2070 MPa tensile (database value) | fasteners, wires and springs |
Applications
- Aerospace and marine fasteners
- Wires and leads in medical devices
- Corrosion-resistant springs
- Oil and gas components
- Small high-strength shafts
Fabrication
Welding
Welded mainly by local methods (resistance or laser). Welding removes the cold-work strength at the weld.
Machining
Nickel alloys work harden, stay strong when hot, and wear tools. Use low speed, a steady feed that does not "rub", sharp rigid tools and plenty of coolant.
Machining
Very hard to machine in the hardened condition.
Compared with similar materials
| Material | Rm / Rp0.2 | Welding | When it is the better choice |
|---|---|---|---|
| Elgiloy | 2070 / 1720 MPa | Laser / EBW | a cobalt spring alloy, with iron · material page |
| Inconel 718 | 1240–1380 / 1035–1170 MPa | Good — ERNiCrMo-6 | an age-hardenable nickel alloy, cheaper · material page |
| Monel K-500 | 1000–1170 / 690–830 MPa | Difficult — Age after welding | nickel-copper, weaker · material page |
Common mistakes
Welding a part whose strength comes from cold work
Strength is lost at the weld.
Aging without enough cold work
Part of the strength comes from cold work.
Using stainless machining parameters
The material is hard and work hardens strongly.
Equivalents, standards and supply
| ASTM | F562 |
|---|---|
| UNS | R30035 |
| Standards | ASTM F562 / AMS 5844 |
| Forms | wire · rod · strip |
| Producers | Fort Wayne Metals · Carpenter |
Learn more
Values are typical and for comparison only. For design, rely on the standard and the mill certificate. Sources: Stellite (Kennametal) and Elgiloy Specialty Metals data sheets, ASTM F1058, and the METAL HUB materials database. Stellite and Elgiloy are trademarks of their owners.
Updated: October 31, 2026