Alloy 400 / Monel 400

A nickel-copper alloy called Monel 400, constituting 67% Ni & 23% Cu, is resistant to salt and caustic solutions, as well as sea water and steam at high temperatures. The only way to harden Monel 400 is through cold working because it is a solid solution alloy. High strength, outstanding weldability, and strong corrosion resistance are all features of this nickel alloy.

Monel 400 offers excellent corrosion resistance to:

  • Caustic Solutions
  • Chlorinated Salts
  • Fluorine & Hydrogen Fluoride


Monel 400 has poor resistance to nitric acid & ammonia systems.

It has varied applications in marine engineering, chemical & hydrocarbon processing equipment, crude petroleum stills, etc.

Chemical Composition:

Element Percentage
Nickel ( Ni ) 65%
Copper ( Cu ) 30%
Aluminium ( Al ) 2.3% - 3.1%
Iron ( Fe ) 2%
Titanium ( Ti ) 0.35%-0.85%
Carbon ( C ) 0.3%

Corrosion Rating:

RATINGS - 0:Unsuitable 1:Poor to Fair 2:Fair 3:Fair to good 4:Good 5:Good to Excellent 6:Normally Excellent

Materials Non-oxidizing or reducing media Liquids Gases
Acid solutions excluding Hydrochloric, phosphoric, sulfuric Neutral solutions, e.g. many Non-oxidizing salt solutions, chlorides, sulfates Alkaline solutions Oxidizing Media Halogen & derivatives
Caustic & mild alkalis, excluding ammonium hydroxide Ammonium hydroxide & amines Acid solutions, e.g. nitric Neutral or alkaline solutions e.g. per sulfates, peroxides, chromates Pitting media, acid ferric chloride solutions Halogen Hydrogen halides, dry, e.g., dry, hydrogen chloride
Moist, e.g. chlorine below dew point Dry, e.g. fluorine above dew point
Alloy 400 5 6 6 1 0 5 1 2 6 3

Note: Maximum Design Temperature: 482°C

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