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 that has demonstrated excellent strength and outstanding 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. Its many uses include marine engineering components, pump shafts, and chemical processing equipment due to its durability in hostile environments. 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. Many times it is 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 aging infrastructure or equipment, Monel 400 alloy stands out as 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 400 Physical Properties

Physical properties of UNS N04400 has a relatively low density of 8.6 g/cm3(0.31 lb/in3).and 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 Chemical Properties

UNS N04400 contains traces amount carbon in its composition, which makes it resistant against most common corrosive media, including nitric acid, hydrofluoric acid, organic acids, etc., but its immunity towards some other acids, such as sulfuric acid might depend on concentration level as well as the presence of certain impurities like chlorides in these acids. It shows excellent resistance towards seawater & brackish water environment because of the presence of copper in its composition, which forms a protective oxide film around these alloys particles when exposed to seawater environment, thus preventing further corrosion. Further, this alloy also shows good resistance towards alkaline media due to the presence of nickel content in its composition, which helps it forming a protective layer on its surface when exposed to alkaline media, thus providing protection against further corrosion.

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 monel 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 upon various parameters, so 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 a variety of 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 temperatures and low temperatures, making it ideal for use in a variety of industries.
  • Monel 400 is also ductile, meaning that it can be easily formed into a variety of shapes.
  • Monel 400 is weldable, making it easy to join together using welding techniques.
  • Monel 400 is also resistant to a variety of 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

Monel alloy exhibits excellent corrosion resistance in both fresh and saltwater environments. It is resistant to oxidation in high-temperature environments and can be used for long periods of time without any degradation or loss of properties. This makes it ideal for use in chemical processing, food processing, marine applications, 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) which provides higher temperature operation than many other alloys.

Welding Monel 400

Welding monel 400 is a challenging and complex process. It requires a skilled welding technician to be able to properly weld this very tough and resilient alloy. Monel 400 has superior welding qualities compared 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 in order for it to be done 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 in order to achieve optimal results.

Monel 400 Thermal Conductivity

Monel 400 has an excellent thermal conductivity which makes it ideal for applications requiring efficient transfer of heat from one area to another. This includes heating systems, cooling systems, 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).

Monel 400 Heat Treatment

Monel 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. It can also be hardened through age-hardening processes such as annealing or precipitation hardening (solution treatment followed by aging).

Monel 400 Machinability

Monel 400 offers outstanding machinability that has been used in a variety of engineering applications. This alloy is ideal for many machining operations due to its high levels of 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 resistance to corrosion. UNS N04400 alloy is also able to combat galling due to its high monel content. Additionally, monel 400 provides excellent weldability and formability qualities that make it suitable for a range of custom engineering projects such as aircraft parts and pipes. Ultimately, monel 400 is incredibly machinable, making it an invaluable option for precision engineering works.


Overall, UNS N04400 is an excellent choice for applications that require high corrosion resistance 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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Monel 400 Alloy (UNS N04400) – Properties, Uses, Composition

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