Alloy 400 (UNS N04400)

Alloy 400 is a nickel-copper single-phase alloy most commonly supplied in a hot worked and annealed condition. Although the grade can be tempered or cold worked to increase its properties, in its standard annealed condition, it is easy to form and fabricate with no requirements for additional heat treatments to re-balance the alloy. It retains excellent mechanical properties at sub-zero temperatures. Strength and hardness increase with only a slight loss of ductility and impact resistance.

Alloy 400 possesses excellent corrosion resistance to many reducing media. It can be used in contact with fluorine, hydrofluoric acid, hydrogen fluoride or their derivatives – its resistance to hydrofluoric acid has been demonstrated in all concentrations up to the boiling point. It is also resistant to many forms of sulfuric and hydrochloric acids under reducing conditions and it also performs well in seawater. Alloy 400 is also resistant to stress corrosion cracking and pitting in most fresh and industrial waters. It is therefore widely used in marine engineering, chemical and hydrocarbon processing equipment, valves, pumps, shafts, fittings, fasteners, and heat exchangers.