Nickel Alloy Monel 401-SPR (Spring Temper)
Supply condition
UNS N04401
For coil and flat springs, contact fingers and resistance elements needing high elastic limit.
Values for the SPR condition
Other Monel 401 tempers and conditions
Monel 401 is listed in 6 conditions; see the grade overview at Monel 401.
Compare all 6 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
ANNDefault Annealed | Standard stocked condition: maximum ductility for stamping, drawing and coil winding, most stable resistivity. | 170 | 470 | 42 | 115 HB | — |
Quarter hard | Choose when slightly higher stiffness and better blanking edge quality are needed but forming is still required. | 350 | 550 | 25 | 150 HB | 3.6 % IACS |
Half hard | Balance of strength and remaining bend ductility for contacts, clips and formed terminals. | 470 | 620 | 15 | 185 HB | 3.5 % IACS |
Stress relieved | Cold-worked material given a 260–370 °C stabilizing treatment to lock in resistance value and reduce residual stress/drift. | 600 | 700 | 8 | 210 HB | 3.5 % IACS |
Hardened | Maximum strength and hardness from cold work; use for flat springs, straight wire and machined parts needing good chip control. | 620 | 730 | 6 | 20 HRC | 3.5 % IACS |
SPRThis page Spring Temper | For coil and flat springs, contact fingers and resistance elements needing high elastic limit. | 720 | 830 | 3 | 22 HRC | 3.5 % IACS |
What is Monel 401-SPR?
Monel 401-SPR is Monel 401 supplied in the SPR condition — for coil and flat springs, contact fingers and resistance elements needing high elastic limit. Monel 401-SPR has a yield strength of 720 MPa (104 ksi) and a tensile strength of 830 MPa (120 ksi) — stronger than 82% of nickel alloy grades. Elongation at break is 3% and the elastic modulus is 170 GPa (24.7 Msi). Monel 401-SPR has a density of 8.86 g/cm³ (0.32 lb/in³), heavier than 85% of nickel alloy grades. It melts at 1,260°C (2,300 °F). ANN is the default condition FabDigit quotes; SPR is available on request or by drawing note.
Advantages
- Easy to machine — 38/100, better than 98% of nickel alloy grades
- Low embodied carbon — 7.5 kg CO₂/kg, better than 96% of nickel alloy grades
- High electrical conductivity — 3.5 % IACS, better than 91% of nickel alloy grades
- Conducts heat well — 21 W/m·K (12.1 BTU/hr·ft·°F), better than 88% of nickel alloy grades
- High strength — 720 MPa (104 ksi), better than 82% of nickel alloy grades
Limitations
- Limited service temperature — 260°C (500 °F), worse than 99% of nickel alloy grades
- Limited ductility — 3%, worse than 93% of nickel alloy grades
- Low stiffness — 170 GPa (24.7 Msi), worse than 91% of nickel alloy grades
- Needs corrosion protection — 66/100, worse than 84% of nickel alloy grades
- Limited formability — 15/100, worse than 81% of nickel alloy grades
Monel 401-SPR properties
Typical room-temperature values for Monel 401-SPR; 22 are specific to this condition. Other listed values are Monel 401 reference data and may not represent this condition. Bars are the position among nickel alloy grades.
Physical3
Monel 401-SPR has a density of 8.86 g/cm³ (0.32 lb/in³), heavier than 85% of nickel alloy grades. It melts at 1,260°C (2,300 °F).
Mechanical14
Monel 401-SPR has a yield strength of 720 MPa (104 ksi) and a tensile strength of 830 MPa (120 ksi) — stronger than 82% of nickel alloy grades. Elongation at break is 3% and the elastic modulus is 170 GPa (24.7 Msi).
Thermal6
Monel 401-SPR is rated for continuous service to 260°C (500 °F). It conducts heat at 21 W/m·K (12.1 BTU/hr·ft·°F), better than 88% of nickel alloy grades. Thermal expansion is 14.2 µm/m·K (7.89 µin/in·°F).
Electrical3
Monel 401-SPR conducts electricity at 3.5 % IACS, better than 91% of nickel alloy grades.
Chemical & Environmental3
Corrosion resistance is good (66/100), worse than 84% of nickel alloy grades.
Sustainability4
Producing a kilogram of Monel 401-SPR takes about 105 MJ of energy and emits 7.5 kg of CO₂ — less than 94% of nickel alloy grades. Typical recycled content is 30%.
Manufacturability8
Monel 401-SPR's machinability is fair (38/100, better than 98% of nickel alloy grades); weldability fair (45/100); formability poor (15/100).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with Monel 401-SPR
Is Monel 401 easy to machine?
Work-hardens rapidly — use sharp, positive-rake carbide, heavy positive feed, rigid setup, low-to-moderate speed and flood sulfur-free coolant; avoid dwelling.
Can Monel 401 be welded?
GTAW/GMAW with Monel-type Ni-Cu filler (ERNiCu-7); keep parts free of sulfur, lead and grease, use low heat input and no post-weld hardening treatment.
Can Monel 401 be formed, bent or molded?
Excellent cold formability in the annealed temper (deep drawing, coiling, stamping); interstage anneal at 760–870 °C followed by rapid cooling after heavy reductions.
What surface finishes work on Monel 401?
Not anodizable; pickle or bright-anneal to remove oxide, then polish, or electroplate Ni/Ag/Au for solderable, low-contact-resistance surfaces.
Monel 401 chemical composition (wt %)
Limits by weight percent from the governing specification, written the way the spec states them — a single maximum for impurities, a range for alloying elements, and the base element as balance. Nominal is the typical mid-range value.
| Element | Spec limit (wt %) | Nominal |
|---|---|---|
| NiNi + Co | 40 – 45 | 43 |
| Mn | ≤ 2.25 | 1.6 |
| Fe | ≤ 0.75 | 0.3 |
| C | ≤ 0.1 | 0.05 |
| Si | ≤ 0.25 | 0.1 |
| S | ≤ 0.02 | 0.01 |
| Cubalance, approx. 53–57 % | balance | — |
Monel 401-SPR — frequently asked
What is Monel 401-SPR used for?
Monel 401-SPR is typically used for electrical resistors, thermostat components and corrosion-resistant springs. In short: controlled-resistivity Monel; corrosion-resistant spring material; high cold formability annealed.
What is the yield strength of Monel 401-SPR?
Monel 401-SPR has a typical yield strength of 720 MPa (104 ksi) and a tensile strength of 830 MPa (120 ksi) — stronger than 82% of nickel alloy grades. Strength varies by condition: see the 6 listed tempers.
Is Monel 401-SPR easy to machine?
Not especially — machinability is rated fair (38/100, better than 98% of nickel alloy grades). Work-hardens rapidly — use sharp, positive-rake carbide, heavy positive feed, rigid setup, low-to-moderate speed and flood sulfur-free coolant; avoid dwelling.
Can Monel 401-SPR be welded?
With care — weldability is rated fair (45/100). GTAW/GMAW with Monel-type Ni-Cu filler (ERNiCu-7); keep parts free of sulfur, lead and grease, use low heat input and no post-weld hardening treatment.
What surface finishes work on Monel 401-SPR?
Not anodizable; pickle or bright-anneal to remove oxide, then polish, or electroplate Ni/Ag/Au for solderable, low-contact-resistance surfaces.
Can Monel 401-SPR be formed, bent or molded?
Excellent cold formability in the annealed temper (deep drawing, coiling, stamping); interstage anneal at 760–870 °C followed by rapid cooling after heavy reductions.
What is the maximum service temperature of Monel 401-SPR?
Monel 401-SPR is rated for continuous use to about 260°C (500 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
What is the difference between Monel 401-ANN and Monel 401-SPR?
ANN is the default condition — standard stocked condition: maximum ductility for stamping, drawing and coil winding, most stable resistivity. SPR: for coil and flat springs, contact fingers and resistance elements needing high elastic limit. Yield strength is 170 MPa in ANN versus 720 MPa in SPR.
Sources
- Monel alloy 401 product data (Ni-Cu resistance alloy) — Special Metals Corporation (2005)
- ASM Handbook Vol. 2: Properties and Selection — Nonferrous Alloys and Special-Purpose Materials — ASM International (1990)
- ASM Handbook Vol. 13B: Corrosion — Materials — ASM International (2005)
- UNS N04401 designation (Metals & Alloys in the Unified Numbering System) — SAE/ASTM (2017)
Property data is compiled from published supplier and standards handbooks and normalised for comparison. Nothing on this page is a certification — request mill certs, CoC or material test reports with your order.