Copper-Nickel alloy monel

Monel is a corrosion-resistant copper-nickel alloy. The main components are nickel (Ni), copper (Cu), ferrum (Fe), , and manganese (Mn). It has high corrosion resistance and ultimate strength, good plasticity. It is used in the chemical, oil, shipbuilding, medical industry, and hardware engineering.

Monel-metal was developed by David Brown, a metallurgist from the USA who had the position of the chief metallurgist at the company International Nickel Co. This material was named after the company's President, Ambrose Monel. The patent for the monel alloy was obtained in 1906.

The main practical useful property of monel metal is the high corrosion resistance of this material in various aggressive environments. Monel is stable in solutions of neutral, alkaline and slightly acidic salts, carbonic, hydrochloric, sulfuric, nitric and acetic acids. Also, this alloy is resistant to most organic acids and practically does not corrode in neutral and alkaline solutions of organic compounds. Monel metal also shows high resistance to corrosion in solutions of alkalis, dry gas atmosphere at room temperature, sea and fresh water.

It is worth noting monel high strength among its mechanical properties.

Technological properties, such as high plasticity, allow to process the material easily by pressure in both hot and cold conditions. It also has good weldability. But mechanical processing must be carried out with a low cutting speed and feed due to rapid hardening.

Property	Value
Density, g/cm3	8.8
Melting point, °С	1350
Electrical resistivity, Ohms·mm2/m	0.425
Magnetic field	Magnetic/nonmagnetic (depending on the grade)
Hardness, НВ	135 (after annealing) 210
Temperature coefficient of linear expansion, °С-1 in the range of 20-100 °С	14·10-6
Temperature coefficient of electrical resistance, °C-1	1.9·10-3

In Russia, monel metal is produced under the grade NiCuFeMn 28-2,5-1,5. This alloy contains cuprum (Cu) - 27-29%, ferrum (Fe) - 2-3%, manganese (Mn) - 1.2-1.8%, nickel + cobalt (Ni + Co) - the rest.

Foreign industry produces monel grades 400, 401, 404, R-405, K-500. These brands differ slightly in their chemical composition. As a rule, the differences are in the presence of certain alloying elements and the percentage of certain impurities. For example, the alloy K-500 is alloyed with aluminum and titanium, which increases the strength and hardness of the alloy.

Advantages:
• it has a high resistance to corrosion in many aggressive environments;
• it has fairly high strength characteristics;
• it has good technological properties - plasticity and weldability.

Disadvantages:
• the alloy is quite expensive compared to other corrosion-resistant materials.

Application areas of the copper-nickel alloy monel are determined by its properties. The main practical useful property is high resistance to corrosion in a variety of aggressive environments. This makes it possible to use monel as a structural material for creating vessels, pipelines for the transfer of aggressive substances and corresponding fittings, pump and compressor shafts, and technological equipment for the oil and gas industry. Also, monel metal can be melted on the surface of parts made of non-corrosion resistant materials in order to protect them from corrosion.

Some grades of monel metal have fairly small temperature coefficients of electrical resistance and average values of specific electrical resistance. These features allow to use the specified alloy of the appropriate grades in specialized electrical and electronic devices.

The industry produces the next main types of products: monel wire, filament (wire of small diameters), monel rods (round bars), pipes, sheets. All of these products are used in areas where there are high requirements for the corrosion resistance of materials.