| Element |
Content (mass %) |
| Nickel (Ni) |
Balance (min. ~63) |
| Copper (Cu) |
28 – 34 |
| Iron (Fe) |
≤ 2.5 |
| Manganese (Mn) |
≤ 2.0 |
| Silicon (Si) |
≤ 0.5 |
| Carbon (C) |
≤ 0.3 |
| Sulfur (S) |
≤ 0.024 |
| Property |
SI Value |
Imperial Value |
| Density |
8.8 g/cm³ |
0.318 lb/in³ |
| Melting range |
1300 – 1350 °C |
2370 – 2460 °F |
| Electrical conductivity |
34 % IACS |
34 % IACS |
| Hardness (annealed) |
65 HRB |
65 HRB |
| Property |
Condition |
SI Value |
Imperial Value |
| Tensile strength |
Annealed |
517 – 620 MPa |
75 – 90 ksi |
| Yield strength (0.2 %) |
Annealed |
172 – 345 MPa |
25 – 50 ksi |
| Modulus of elasticity |
All |
179 GPa |
26 000 ksi |
| Poisson’s ratio |
All |
0.32 |
0.32 |
| Property |
SI Value |
Imperial Value |
| Thermal conductivity (20 °C) |
21.8 W/m·K |
12.6 BTU·ft/(h·ft²·°F) |
| Linear expansion coefficient (20–100 °C) |
13.9 μm/m·°C |
7.72 μin/in·°F |
| Specific heat |
427 J/kg·K |
0.102 BTU/lb·°F |
| Melting range |
1300 – 1350 °C |
2370 – 2460 °F |
The conductivity, expansion and specific heat values come from general technical literature for Monel 400.
| Designation / Standard |
Description |
| UNS N04400 |
Unified numbering system |
| AMS 4574 |
Aerospace material specification |
| AMS 4675 |
Wire or bar for rivets |
| AMS 4731 |
Seamless tube |
| ASTM B163 |
Tube for condensers and heat exchangers |
| ASTM B165 |
Seamless pipe |
| ASTM F96 |
Product specification for forging |
| Process |
Details |
| Hot working |
648 – 1176 °C (1200 – 2150 °F) |
| Annealing |
760 – 980 °C (1400 – 1800 °F), controlled cooling |
| Cold working |
High work hardening capacity; progressive reductions recommended |
| Forging |
Controlled procedures, uniform preheating |
| Machinability |
Difficult – work hardens rapidly during cutting; use low speeds and reduced feeds |
Monel 400 readily accepts the most common processes: shielded metal arc welding (SMAW), gas tungsten arc welding (GTAW / GMAW) and submerged arc welding (SAW). Consumables of similar composition (e.g., ERNiCu-7) are recommended, along with thorough pre-cleaning to avoid sulfur or lead contamination.
| Medium / Condition |
Behavior of Monel 400 |
| Seawater (static and high flow) |
Very resistant; noble position in galvanic series (close to Inconel 625) |
| Hydrofluoric acid (HF) |
Exceptional resistance at all concentrations up to boiling point |
| Sulfuric acid (reducing) |
Satisfactory resistance in absence of oxidizing agents |
| Hydrochloric acid |
Good resistance at moderate concentrations without aeration |
| Chlorides and stress cracking |
Virtually immune to stress cracking in presence of chlorides |
| Alkaline environments |
Excellent resistance to caustic solutions up to elevated temperatures |
| Industry |
Examples of use |
| Marine |
Propeller shafts, seawater valves, anchor cables, filter baskets, tow wire |
| Oil & Gas |
Components of alkylation units in contact with HF, process piping, heat exchangers |
| Aerospace |
Safety wiring in hot zones, skin sheets on experimental aircraft (e.g., North American X-15) |
| Chemical |
Pumps, valves and piping for hydrofluoric acid and caustic solutions |
| Instrumentation |
Magnetic field detector housings, non-magnetic anchors for minesweepers |
| Property |
Monel 400 |
Monel K‑500 |
Stainless steel 316 |
Hastelloy C‑276 |
Titanium grade 2 |
| Tensile strength (MPa) |
517–620 |
965–1240 |
515–690 |
690–830 |
345–490 |
| Density (g/cm³) |
8.8 |
8.5 |
8.0 |
8.9 |
4.5 |
| Seawater resistance |
Excellent |
Excellent |
Good (risk of pitting) |
Excellent |
Excellent |
| HF resistance |
Exceptional |
Exceptional |
Limited |
Excellent |
Moderate |
| Relative cost |
High |
Very high |
Low |
Very high |
High |
The tensile strength in the annealed condition can reach 620 MPa (90 ksi), allowing its use in structural components subjected to moderate loads.
Monel 400 retains good strength and toughness up to approximately 540 °C (1000 °F) in continuous service in oxidizing atmospheres, and at cryogenic temperatures down to –196 °C it does not exhibit a ductile-to-brittle transition.
The density of Monel 400 is 8.8 g/cm³ (0.318 lb/in³), a value slightly higher than that of common stainless steels.
Yes, Monel 400 can be welded using processes such as SMAW, GTAW, GMAW and SAW with compatible filler metals (e.g., ERNiCu-7), provided the surfaces are properly cleaned.
Monel 400 resists all concentrations of hydrofluoric acid up to the boiling point, being one of the few engineering alloys that can withstand prolonged exposures to this acid under reducing conditions.
The modulus of elasticity of Monel 400 is 179 GPa (26 000 ksi), giving it an intermediate stiffness between steels and aluminum alloys.