Nickel Alloy Monel 400 · temper · default condition
Nickel Alloy Monel 400-O
Properties of the O condition, compared with the other Monel 400 tempers.
Standard stocked condition for plate, sheet, tube and welded fabrications where maximum formability and corrosion performance are wanted.
What is Monel 400-O?
Monel 400-O is Monel 400 in the O temper — standard stocked condition for plate, sheet, tube and welded fabrications where maximum formability and corrosion performance are wanted. Monel 400-O has a yield strength of 240 MPa (34.8 ksi) and a tensile strength of 550 MPa (79.8 ksi) — weaker than 89% of nickel alloy grades. Elongation at break is 45% and the elastic modulus is 179 GPa (26 Msi). Monel 400-O has a density of 8.8 g/cm³ (0.318 lb/in³), heavier than 81% of nickel alloy grades. It melts at 1,300°C (2,372 °F).
Advantages
- Forms and bends easily — 85/100, better than 95% of nickel alloy grades
- Conducts heat well — 21.8 W/m·K (12.6 BTU/hr·ft·°F), better than 90% of nickel alloy grades
- High electrical conductivity — 3.2 % IACS, better than 89% of nickel alloy grades
- Easy to machine — 30/100, better than 89% of nickel alloy grades
- Low embodied carbon — 9.5 kg CO₂/kg, better than 88% of nickel alloy grades
Limitations
- Low strength — 240 MPa (34.8 ksi), worse than 89% of nickel alloy grades
- Low stiffness — 179 GPa (26 Msi), worse than 88% of nickel alloy grades
- Limited service temperature — 480°C (896 °F), worse than 81% of nickel alloy grades
Monel 400-O properties
Typical room-temperature values for Monel 400-O — 14 properties are specific to this condition; the rest are grade-level values shared by every Monel 400 temper. Each bar shows where the value sits among the nickel alloy grades in FabDigit's library — further right is higher.
Physical3
Monel 400-O has a density of 8.8 g/cm³ (0.318 lb/in³), heavier than 81% of nickel alloy grades. It melts at 1,300°C (2,372 °F).
Mechanical14
Monel 400-O has a yield strength of 240 MPa (34.8 ksi) and a tensile strength of 550 MPa (79.8 ksi) — weaker than 89% of nickel alloy grades. Elongation at break is 45% and the elastic modulus is 179 GPa (26 Msi).
Thermal6
Monel 400-O is rated for continuous service to 480°C (896 °F). It conducts heat at 21.8 W/m·K (12.6 BTU/hr·ft·°F), better than 90% of nickel alloy grades. Thermal expansion is 13.9 µm/m·K (7.72 µin/in·°F).
Electrical3
Monel 400-O conducts electricity at 3.2 % IACS, better than 89% of nickel alloy grades.
Chemical & Environmental3
Corrosion resistance is very good (78/100), better than 50% of nickel alloy grades.
Sustainability4
Producing a kilogram of Monel 400-O takes about 120 MJ of energy and emits 9.5 kg of CO₂ — less than 89% of nickel alloy grades. Typical recycled content is 35%.
Manufacturability7
Monel 400-O's machinability is poor (30/100, better than 89% of nickel alloy grades); weldability very good (82/100); formability excellent (85/100).
Common Calculations5
Values are nominal handbook figures for design screening. Certified mill or lot data ships with every FabDigit order on request.
Other Monel 400 tempers and conditions
Monel 400 is also supplied in 4 other conditions. The full side-by-side table is on the Monel 400 overview.
- ODefaultStandard stocked condition for plate, sheet, tube and welded fabrications where maximum formability and corrosion performance are wanted.240 MPa yield · 125 HB
- Cold Rolled HardSpring-temper strip and diaphragms where high yield strength and stiffness in thin section outweigh formability.690 MPa yield · 25 HRC
- Cold Drawn Stress RelievedUse where cold-drawn strength must be kept but residual stress (distortion on machining, SCC risk) has to be reduced.550 MPa yield · 215 HB
- Cold DrawnChoose for shafting, fasteners and machined parts needing higher yield strength, better surface finish and improved chip control.480 MPa yield · 200 HB
- Hot FinishedEconomical condition for large-section bar, forgings and as-rolled plate where mid-range strength is acceptable.310 MPa yield · 150 HB
Working with Monel 400-O
Is Monel 400 easy to machine?
Work-hardens rapidly — use rigid setups, positive-rake sharp carbide, heavy positive feed and constant engagement, moderate speed (~25–40 m/min carbide) with flood sulfurized oil; never dwell in the cut.
Can Monel 400 be welded?
Readily welded by GTAW/GMAW/SMAW with Monel Filler Metal 60 (ERNiCu-7) or Electrode 190; keep surfaces free of sulfur, lead and grease, use low heat input and no preheat, and avoid autogenous welds (add Ti-bearing filler to prevent porosity).
Can Monel 400 be formed, bent or molded?
Excellent cold formability in the annealed condition (deep drawing, spinning, bending) but high springback and fast work hardening — plan interstage anneals at 760–870 °C; hot work at 870–1175 °C and finish above 650 °C.
What surface finishes work on Monel 400?
Pickle in nitric-hydrofluoric or bright-dip after annealing to remove the tenacious green-black oxide; takes a fine mechanical polish, accepts electroless nickel or silver plating, and needs no coating for seawater service.
Monel 400 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, minimum per ASTM B127/B164 | ≥ 63 | 66 |
| Fe | ≤ 2.5 | 1.6 |
| Mn | ≤ 2 | 1 |
| C | ≤ 0.3 | 0.15 |
| Si | ≤ 0.5 | 0.2 |
| S | ≤ 0.02 | 0.01 |
| Cubalance in practice | ≥ 28 (balance) | — |
Monel 400-O — frequently asked
What is Monel 400-O used for?
Monel 400-O is typically used for seawater valve bodies and trim, marine pump shafts and casings, heat exchanger tubing and tubesheets, hydrofluoric acid process piping, feedwater heater components and chemical processing vessels and liners. In short: seawater-resistant nickel-copper.
What is the yield strength of Monel 400-O?
Monel 400-O has a typical yield strength of 240 MPa (34.8 ksi) and a tensile strength of 550 MPa (79.8 ksi) — weaker than 89% of nickel alloy grades. Strength varies by condition: see the 5 listed tempers.
Is Monel 400-O easy to machine?
Not especially — machinability is rated poor (30/100, better than 89% of nickel alloy grades). Work-hardens rapidly — use rigid setups, positive-rake sharp carbide, heavy positive feed and constant engagement, moderate speed (~25–40 m/min carbide) with flood sulfurized oil; never dwell in the cut.
Can Monel 400-O be welded?
Yes — weldability is rated very good (82/100). Readily welded by GTAW/GMAW/SMAW with Monel Filler Metal 60 (ERNiCu-7) or Electrode 190; keep surfaces free of sulfur, lead and grease, use low heat input and no preheat, and avoid autogenous welds (add Ti-bearing filler to prevent porosity).
What surface finishes work on Monel 400-O?
Pickle in nitric-hydrofluoric or bright-dip after annealing to remove the tenacious green-black oxide; takes a fine mechanical polish, accepts electroless nickel or silver plating, and needs no coating for seawater service.
Can Monel 400-O be formed, bent or molded?
Excellent cold formability in the annealed condition (deep drawing, spinning, bending) but high springback and fast work hardening — plan interstage anneals at 760–870 °C; hot work at 870–1175 °C and finish above 650 °C.
What is the maximum service temperature of Monel 400-O?
Monel 400-O is rated for continuous use to about 480°C (896 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
Can FabDigit make parts in Monel 400-O?
Yes — Monel 400-O is available for CNC machining and sheet metal with instant online pricing. Upload a STEP file to get a price and a DFM check.
Sources
- ASTM B127 — Nickel-Copper Alloy Plate, Sheet and Strip — ASTM International (2019)
- ASTM B164 — Nickel-Copper Alloy Rod, Bar and Wire — ASTM International (2020)
- MONEL alloy 400 Technical Bulletin — 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)
- GB/T 15007 / NCu30 — SAC (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.