Monel 400 is a nickel-copper alloy with superb seawater resistance, excellent corrosion resistance and mechanical properties.
Standards of Monel 400
Plate Standard: ASTM B127 ASME SB127
Forging Standard: ASTM B564 ASME SB564
The standard grades of Monel 400 mainly include ASTM B127, B163, B164, and AMS 4675, AMS 4544 and so on.
In addition, the UNS number for Monel 400 is N04400. It also includes the German DIN standard NiCu30Fe (W-Nr: 2.4360 or 2.4630). China’s GB/T standard for MCu-28-1.5-1.8 etc..
These standard grades specify in detail the chemical composition, physical properties, processing requirements, etc. of Monel 400 alloy. This ensures its stability and reliability in various applications.
Monel 400 Chemical Composition
The main components of Monel 400 are NICKEL and COPPER. The content of nickel is about 63% to 70%, and the content of copper is about 28% to 34%. In addition, small amounts of iron (≤2.5%), manganese (≤2.0% or ≤1.5%), carbon (≤0.3%), silicon (≤0.5%) and sulfur (≤0.024%) are also present. The precise proportions and content requirements of these elements are usually specified by the relevant standards to ensure the stability and consistency of the material.
It is a nickel-based alloy, often referred to as N04400, and is a high-volume, versatile corrosion-resistant alloy with excellent all-around performance. This alloy has excellent corrosion resistance in hydrofluoric acid and fluorine gas media. It also has excellent corrosion resistance to hot concentrated alkaline solutions. It is also resistant to corrosion from neutral solutions, water, seawater, atmosphere, organic compounds, and so on. An important feature of this alloy is that it is generally free from stress corrosion cracks and has good cutting properties.
Metallographic Structure
The metallographic structure of Monel 400 is a high-strength single-phase solid solution. It could also be described as having a single-phase austenitic organization.
It also exhibits equiaxial grains with coarse dendrites and fine columnar crystals. This is due to the low content of impurity elements in the alloy. This grain structure facilitates the improvement of the steel’s cutting properties, and thus Monel 400 exhibits good machinability.
Corrosion Resistance
Excellent corrosion resistance in fluorine gas, hydrochloric acid, sulfuric acid, hydrofluoric acid and their derivatives. In seawater it is more corrosion resistant than copper based alloys.
Corrosion resistant in sulfuric acid at concentrations less than 85%. It is one of the few important materials that can resist hydrofluoric acid.
In most cases of water corrosion, the corrosion resistance is excellent. Pore corrosion, stress corrosion, etc. are rarely found. The corrosion rate is less than 0.025mm/a.
The maximum temperature for continuous operation in air is generally around 600°C. In high temperature steam, the corrosion rate is less than 0.026mm/a.
Monel 400 has a high nickel content. Therefore, it is resistant to corrosion in anhydrous ammonia and ammoniated conditions below 585°C.
Applications of Monel 400
Monel400 alloy is a versatile material that finds application in many industrial fields.
Seamless water pipelines and steam pipes in power plants.
Seawater exchangers and evaporators.
Sulfuric and hydrochloric acid environments.
Crude oil distillation.
Pump shafts and propellers in seawater use equipment.
Equipment used in the nuclear industry for manufacturing uranium refining and isotope separation.
Pumps and valves used in the manufacture of equipment for the production of hydrochloric acid.
And much more.
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