Monel 400 is a nickel-copper alloy (about 67% Ni - 23% Cu) that is resistant to sea water and steam at high temperatures as well as to salt and caustic solutions. Alloy 400 is a solid solution alloy that can only be hardened by cold working.
This nickel alloy exhibits characteristics like good corrosion resistance, good weldability and high strength. A low corrosion rate in rapidly flowing brackish or seawater combined with excellent resistance to stress-corrosion cracking in most freshwaters, and its resistance to a variety of corrosive conditions led to its wide use in marine applications and other non-oxidizing chloride solutions.