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Monel400 (UNS N04400) is a nickel-copper alloy with a composition ratio of Ni67-Cu23. It is currently the nickel-copper corrosion-resistant alloy with the largest usage, the widest application, and the best overall performance.
Alloy 400 monel has excellent corrosion resistance in hydrofluoric acid and fluorine gas media, and also has excellent corrosion resistance to hot concentrated alkali solution. It is also resistant to corrosion by neutral solutions, water, seawater, atmosphere, organic compounds, etc. An important feature of this alloy is that it generally does not produce stress corrosion cracks and has good cutting performance!
Monel alloy 400 (UNS N04400) is a solid-solution alloy that can be hardened only by cold working. This alloy has excellent corrosion resistance in hydrofluoric acid and fluorine gas medium, and also has excellent corrosion resistance in hot concentrated lye. At the same time, it is also resistant to corrosion by neutral solutions, water, seawater, atmosphere, organic compounds, etc. An important feature of this alloy is that it generally does not produce stress corrosion cracking and has good machinability. It is a corrosion-resistant alloy with the largest amount, the most widely used and excellent comprehensive properties.
Alloy 400 is widely used in many fields, especially marine and chemical processing. Typical applications are pump and propeller shafts; marine fixtures and fasteners; electrical and electronic components; springs; chemical processing equipment; gasoline and fresh water tanks; crude petroleum stills,process vessels and piping; boiler feedwater heaters andother heat exchangers; and deaerating heaters.
Grade | C≤ | Mn≤ | Si | S≤ | Cu | Fe≤ | Ni≤ |
Monel400 | 0.3 | 2 | 0.5 | 0.024 | 28.0-34.0 | 2.5 | 63 |
Product Form | Condition | Tensile(Ksi) | .2% Yield (Ksi) | Elongation(%) | Hardness(HRB) |
Rod&Bar | Annealed | 75-90 | 25-50 | 60-35 | 60-80 |
Rod&Bar | Cold-Drawn Stress Relieved | 84-120 | 55-100 | 40-22 | 85-20HRC |
Plate | Annealed | 70-85 | 28-50 | 50-35 | 60-76 |
Sheet | Annealed | 70-85 | 30-45 | 45-35 | 65-80 |
Tube&Pipe Seamless | Annealed | 70-85 | 25-45 | 50-35 | 75 max* |
Density | 8.80g/cm3 | |
Elastic modulus | 26 000 ksi | |
Heating energy | 0.427 J/g-°C | |
| Coefficient of Thermal Expansion | 70-200F | 7.7 |
70-400F | 8.6 | |
70-800 F | 8.9 | |
70-1000F | 9.1 | |
Product | Standard | Show |
Monel 400 Seamless Pipe | ASTM B165 |  |
Monel 400 Welded Pipe | ASTM B474 |  |
Monel 400 Seamless Tube | ASTM B163/B165 |  |
Monel 400 Sheet | ASTM B127 |  |
Monel 400 Bars | ASTM B164 |  |
Monel 400 Forging | ASTM B564 |  |
Monel 400 Fittings | ASTM B366 |  |
JN Monel400 material has excellent hot and cold processing properties. Alloy 400 Monel products are complete. We can provide plates, strips, tubes, wires, rods, forgings, fasteners, flanges, pipe fittings and other products.
STANDARD | WERKSTOFF NR. | UNS | JIS | BS | GOST | AFNOR | EN |
Monel 400 | 2.4360 | N04400 | NW 4400 | NA 13 | МНЖМц 28-2,5-1,5 | NU-30M | NiCu30Fe |
Monel 400 alloy has excellent corrosion resistance in fluorine gas, hydrochloric acid, sulfuric acid, hydrofluoric acid and their derivatives, and is one of the few important materials that can resist hydrofluoric acid.
Sulfuric acid environment:
Alloy 400 is corrosion-resistant in sulfuric acid with a concentration of less than 85%.
Aqueous corrosion:
Under most water corrosion conditions, Monel 400 alloy not only has excellent corrosion resistance, but also rarely suffers from pitting corrosion and stress corrosion, with a corrosion rate of less than 0.025mm/a.
High temperature corrosion:
The maximum temperature of alloy 400 in continuous operation in air is generally around 400C, and in high-temperature steam, the corrosion rate is less than 0.026mm/a.
Ammonia:
Due to the high nickel content of Monel 400 alloy, it can resist corrosion under anhydrous ammonia and ammoniated conditions below 585°C.
Monel 400 material annealing temperature is generally between 700 and 900°C, and the best effect is achieved at 825°C. Rapid air cooling after treatment can achieve good corrosion resistance. The purpose of this is to soften the material after forging to keep the material relatively fine particles. The annealing temperature and time are directly related to the final grain size, so the annealing parameters should be carefully considered.
Monel400 can be welded by gas tungsten arc, gas metal arc welding and shielded gas metal arc welding.
Before welding, clean the groove and electrode with acetone, and use GTAW as the welding method. Use ERNiCu-7 as the welding wire and ENICU-7 as the welding electrode.
400 Monel does not require preheating before welding, nor does it require post-weld heat treatment, because the strength of the material is improved after welding, which is beneficial for future use.
The fluidity of the molten metal in 400 material welding is poor, so a large groove angle (60-70°) should be used to allow the welding wire to fill the weld.
Feed water and steam generator tubing
Brine heaters, sea water scrubbers in tanker inert gas systems
Sulfuric acid and hydrofluoric acid alkylation plants
Pickling bat heating coils
Heat exchangers in a variety of industries
Transfer piping from oil refinery crude columns
Plant for the refining of uranium and isotope separation in the production of nuclear fuel
Monoethanolamine (MEA) reboiling tube
Cladding for the upper areas of oil refinery crude columns
Is Alloy 400 the same as Monel?
Yes. "Monel 400" is the original trade name. "Alloy 400" is the common industry designation for the same material. It is also standardized as:
UNS N04400
ASTM B127, B164, B165
EN 2.4360 / 2.4361
In conclusion, "Monel 400" and "Alloy 400" refer to the identical nickel-copper alloy. "Monel" alone is ambiguous, as it refers to a series of alloys.
Is Monel 400 magnetic?
No. Monel 400 is essentially non-magnetic at all temperatures.
Its primary constituents are nickel and copper, both inherently non-ferromagnetic elements. Minor iron content is insufficient to impart significant magnetic permeability. While non-magnetic like austenitic stainless steels, very slight magnetic response might be detectable with extremely sensitive instruments due to trace impurities or cold working, but it is not considered a magnetic material for practical engineering purposes.
How to Weld Monel 400?
Welding Monel 400 requires specific techniques to maintain its corrosion resistance and mechanical properties.
Aspect | Recommendation | Reason |
Cleanliness | Critical: Degrease + stainless steel wire brush | Prevents contamination leading to porosity/cracking |
Welding Processes | GTAW (TIG): Preferred | Best control with TIG; MIG requires spray transfer |
Filler Metal | ENiCu-7 (AWS A5.11/5.14) | Matches base metal composition (e.g., Monel 60, 70, or 190) |
Joint Design | Wider gaps + larger root openings vs steel | Accommodates higher thermal expansion |
Preheat/Interpass Temp | Not usually required | Prevents excessive grain growth |
Heat Input | Low to Moderate | Maintains corrosion resistance & mechanical properties |
Technique | Stringer beads | Minimizes heat input and oxidation |
Post-Weld Treatment | Not required for most applications | Stress relief may be needed for severe service conditions |
