Monel 400

General Description

Monel 400(UNS N04400/2.4360) is a nickel-copper alloy with high strength and excellent resistance to a range of media including seawater, dilute hydrofluoric and sulfuric acids, and alkalies.

Monel 400 containing about 30–33% copper in a nickel matrix has many similar characteristics of commercially pure nickel, while improving upon many others. Addition of some iron significantly improves the resistance to cavitation and erosion in condenser tube applications. The main uses of Monel 400 are under conditions of high flow velocity and erosion as in propeller shafts, propellers, pump-impeller blades, casings, condenser tubes, and heat exchanger tubes. Corrosion rate in moving seawater is generally less than 0.025 mm/year. The alloy can pit in stagnant seawater, however, the rate of attack is considerably less than in commercially pure alloy 200. Due to its high nickel content (approx. 65%) the alloy is generally immune to chloride stress corrosion cracking. The general corrosion resistance of Monel 400 in nonoxidizing mineral acids is better compared to nickel. However, it suffers from the same weakness of exhibiting very poor corrosion resistance to oxidizing media such as nitric acid, ferric chloride, cupric chloride, wet chlorine, chromic acid, sulfur dioxide, or ammonia. In unaerated dilute hydrochloric and sulfuric acid solution the alloy has useful resistance up to concentrations of 15% at room temperature and up to 2% at somewhat higher temperature, not exceeding 50°C. Due to this specific characteristic, Monel 400 produced by NiWire is also used in processes where chlorinated solvents may form hydrochloric acid due to hydrolysis, which would cause failure in standard stainless steel.

Monel 400 possesses good corrosion resistance at ambient temperatures to all HF concentration in the absence of air. Aerated solutions and higher temperature increase the corrosion rate. The alloy is susceptible to stress corrosion cracking in moist aerated hydrofluoric or hydrofluorosilic acid vapor. This can be minimized by deaeration of the environments or by stress relieving anneal of the component in question.

Typical applications are valve and pump parts, propeller shafts, marine fixtures and fasteners, electronic components, chemical processing equipment, gasoline and freshwater tanks, petroleum processing equipment, boiler feedwater heaters and other heat exchangers

Chemical Composition

Grade Ni% Cu% Fe% C% Mn% Si% S%
Monel 400 63.0-70.0 28.0-34.0 Max 2.5 Max 0.3 Max 2.0 Max 0.5 Max 0.024

Designations

UNS N04400

Werkstoff Nr.  2.4360

Specifications

Monel 400 Wire: ASTM B164

Monel 400 Bar: ASTM B164

Monel 400 Forging: ASTM B564

Monel 400 Pipe/Tube: ASTM B165/730

Monel 400 Sheet/Strip: ASTM B127

Physical Properties

Density:8.83 g/cm3

Melting Point: 1300°C-1390°C

Mechanical Properties

Temper: Solution Annealed

Tensile: Min 480 MPa

Yield: Min 170 MPa

Elongation: 35%

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