ThePipingMart Blog Grades Monel 400 Alloy (UNS N04400) – Properties, Uses, Composition

Monel 400 Alloy (UNS N04400) – Properties, Uses, Composition

what is monel

What is Monel 400?

UNS N04400 is a nickel-iron-copper alloy with excellent strength and resistance to caustic liquids and acids. It is also very malleable, making it easy to work with. The P-Number of base metal Monel 400(UNS N04400) is 42. Due to its durability in hostile environments, its many uses include marine engineering components, pump shafts, and chemical processing equipment. Monel alloy 400 is a mission-critical material for several industries, and it is often used in high-temperature situations due to its modest expansion rate. It is often chosen due to its exceptional weldability and corrosion resistance even when exposed to marine environments or de-icing salts. When it comes time to replace ageing infrastructure or equipment, Monel 400 alloy is the best choice.

What Forms is Monel 400 Available at Piping Mart?

  • Nut
  • Bar
  • Bolt
  • Pipe
  • Screw
  • Tubing
  • Valves
  • Washers
  • Flanges
  • Fasteners
  • Electrodes
  • Stud Bolts
  • Sheet Plates
  • Pipe Fittings
  • Forged Fitting
  • Instrumentation Fittings

Monel 400 Composition

Chemical composition of UNS N04400 is an alloy made of two main elements: nickel (67%-70%) and copper (30%-33%). The key alloying elements in Monel 400 are iron (2.5%), manganese (1%), silicon (.50%), and magnesium (.30%). The remaining components in the alloy are trace amounts of carbon (.08% max), sulfur (.024% max), aluminum (.60%), titanium (.35%), and others trace elements.

Element Content (%)
Nickel, Ni Remainder
Copper, Cu 28-34
Iron, Fe 2.5 max
Manganese, Mn 2 max
Silicon, Si 0.5 max
Carbon, C 0.3 max
Sulphur, S 0.024

Monel UNS N04400 Physical Properties

The physical properties of Alloy 400 have a relatively low density of 8.6 g/cm3(0.31 lb/in3), and the monel 400 hardness is 75. Its melting point ranges between 1350-1400°C (2460-2550°F). This alloy has a thermal expansion coefficient ranging from 11.8 – 12.7 x 10-6 per °C (21-23 x 10-6 per °F) over the temperature range 20 to 100°C (68 to 212°F). Its electrical resistivity at 20°C is around 0.58 µΩ.m with an average specific heat capacity at 0 – 100°C being 420 J/kg.K or 0.10 BTU/lb.°F. It also has good thermal conductivity with a value ranging from 119 W/m•K to 101 W/m•K depending on the temperature range used for measurement, i.e., 0 – 100°C or 300 – 600°C respectively.

Properties Metric Imperial
Density 8.8 gm/cm3 0.318 lb/in3

Monel 400 Specifications



Metal Type

UNS N04400

Monel 400 Bar

ASTM B164 QQ-N-281 Din 17750

Monel 400 Wire

Monel 400 Sheet

ASTM B127 QQ-N-281

Monel 400 Plate

ASTM B127 QQ-N-281

Monel 400 Pipe
Monel 400 Tube

Monel 400 Fitting


Monel 400 Forging


Monel 400 Weld Wire

FM 60/ ERNiCu-7/ 17753

Monel 400 Weld Electrode
FM 190 ENiCu-7



Monel 400 Mechanical Properties

Mechanical properties of Nickel-Copper alloy 400, such as tensile strength, yield strength, elongation & modulus, vary depending upon different factors such as temperature, product form, i.e., plate/sheet/bar, etc., direction & grain size. For instance, at room temperature for sheet & plate materials having grain size larger than ASTM 5, the tensile strength varies from 690 MPa – 827 MPa, whereas yield strength varies from 622 MPa – 796 MPa & elongation differs from 40% – 42%. Similarly, the modulus ranges from 207 GPa – 210 GPa at room temperature for sheet/plate material having grain size larger than ASTM 5. As discussed earlier, these values vary depending on various parameters. One should refer to respective product standards before specifying mechanical requirements while ordering or purchasing any product made up using this alloy.

Properties Metric Imperial
Tensile strength(annealed) 517-620 MPa 75-90 ksi
Yield strength 172-345 MPa 25-50 ksi
Modulus of elasticity 179 GPa 26000 ksi
Poisson’s ratio 0.32 0.32

Monel 400 Uses

UNS N04400 is a highly versatile nickel-copper alloy that has a wide range of applications. It demonstrates excellent corrosion resistance and strong mechanical properties in temperatures up to 1000°F, making it ideal for many industrial environments. Consequently, Monel 400 is often employed in high-pressure and high-temperature applications, including boilers, condensers, heat exchangers, oil refinery equipment, and evaporators. Its resistance to seawater makes it commonly used in marine engineering applications such as propellers, shafts, pump parts, and fasteners. UNS N04400 is also regularly chosen for its strength at elevated temperatures when fabricating engine turbines or turbo fans for power generation systems. Furthermore, its unique ability to be hot-worked or cold-worked provides maximum flexibility when creating complex components for a variety of products that rely on its high-strength characteristics.

  • Monel 400 is a nickel-copper alloy that is resistant to corrosion in both fresh water and salt water.
  • Monel 400 can be used in various applications, including marine engineering, chemical processing, and hydrocarbon processing.
  • Monel 400 is also used in the food industry, as it is non-toxic and does not cause allergies.
  • Monel 400 is resistant to both high and low temperatures, making it ideal for use in various industries.
  • Monel 400 is also ductile, meaning it can be easily formed into various shapes.
  • Monel 400 is weldable, making it easy to join together using welding techniques.
  • Monel 400 is also resistant to various chemicals, including acids, alkalis, and salts.

Monel 400 Equivalent

  • AMS 4574
  • AMS 4675
  • AMS 4731
  • ASTM B163
  • ASTM B165
  • ASTM F96
  • UNS N04400

Monel 400 Corrosion Resistance

The monel alloy exhibits excellent corrosion resistance in both fresh and saltwater environments. Monel UNS N04400 is resistant to oxidation in high-temperature environments and can be used for long periods without any degradation or loss of properties. This makes it ideal for use in chemical, food, marine, and industrial applications where exposure to corrosive substances is common.

Monel 400 Density and Machinability

Monel alloy 400 has a very high density compared to other metals, weighing 8.8 g/cm3. This makes it an excellent material for applications where weight is not a concern but strength is desired – such as engine parts or marine components. Due to its hardness, monel alloy 400 could be more machinable; however, it can be done with the proper tools and techniques. It is important to note that when cutting monel alloy 400, you should use sharp tools with slow speeds as the metal tends to work hard during cutting operations.

Monel 400 Heat Resistance

Monel 400 also exhibits excellent heat resistance, which makes it suitable for use in high-temperature operations such as furnace linings, boiler tubes, exhaust manifolds, and turbine blades. The alloy has a melting point of 2576°F (1413°C), providing higher temperature operation than many other alloys.

Welding Monel 400

Welding monel 400 is a challenging and complex process. A skilled welding technician must properly weld this tough and resilient alloy. Monel 400 has superior welding qualities to other alloys, such as resistance against stress crevices and corrosion fatigue. However, welding monel 400 also requires special welding techniques that must be learned and carefully executed by the welding technician to do it correctly. That is why welding monel 400 must only be done by an experienced and well-trained welding technician who understands the properties and properties of other materials it could be welding with to achieve optimal results.

Monel 400 Thermal Conductivity

400 Monel has excellent thermal conductivity, making it ideal for applications requiring efficient heat transfer from one area to another. This includes heating, cooling, and automotive components such as radiators, exhausts, and catalytic converters. Monel 400 can also be used for electrical components such as switches, connectors, wires, and terminals due to its low electrical resistivity (9 x 10-6 ohm-cm).

Alloy 400 Heat Treatment

Alloy 400 also has good heat treatment characteristics, which make it suitable for applications requiring post-welding treatments or joining processes involving brazing or soldering. It can easily be formed into complex shapes using cold working methods such as drawing or rolling with minimal distortion or cracking. Nickel Alloy 400 can also be hardened through age-hardening processes such as annealing or precipitation hardening (solution treatment followed by ageing).

Monel 400 Machinability

Monel 400 offers outstanding machinability that has been used in various engineering applications. This alloy is ideal for many machining operations due to its high strength and durability, especially when drilling and tapping. It is a nickel-copper alloy that reacts well to the standard machining processes because of its corrosion resistance. UNS N04400 alloy can also combat galling due to its high monel content. Additionally, monel 400 provides excellent weldability and formability qualities that make it suitable for various custom engineering projects such as aircraft parts and pipes. Ultimately, the monel 400 is incredibly machinable, making it an invaluable option for precision engineering.


Overall, UNS N04400 is an excellent choice for applications requiring high corrosion or heat resistance, such as marine equipment, oil rigs, machine parts and fasteners, nuclear reactors, and more. It offers excellent thermal conductivity and heat treatment options while displaying strong mechanical property values across various temperatures and product forms such as sheets, plates, or bars. Its composition provides great chemical resistance against most common corrosive media, including nitric acid, hydrofluoric acid & organic acids, while offering good protection against seawater & brackish water environment, making it ideal for use in harsh environmental conditions like water-based sea applications where the salt spray can cause significant corrosion damage if proper materials are not used.


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