Monel 400 is a Nickel-Copper alloy with great strength and superb corrosion resistance in a range of acidic and alkaline environments and particularly appropriate for reducing conditions. It also possesses good ductility and thermal conductivity.This alloy is most frequently applied in a range of environments going from mildly oxidizing through neutral and to moderately reducing conditions. The additional application area of this material is in marine environments and other non-oxidizing chloride solutions. Like with commercially pure Nickel, Monel 400 is low in strength in the annealed condition, for this reason a variety of tempers are used to achieve higher strength levels.Strength and hardness increase slightly with impairment of ductility or impact resistance. The alloy does not go through a ductile-to-brittle transition even when cooled to the subzero temperatures. This is in contrast to several ferrous materials which are brittle at very low temperatures in spite of their increased strength.

Conventional machining procedures used for iron based alloys may be used. This alloy does work-harden during machining and has higher strength and “gumminess” not typical of steels. Heavy duty machining equipment and tooling should be used to minimalize chatter or work-hardening of the alloy ahead of the cutting. Most any commercial coolant may be used in the machining operations. Water-base coolants are preferred for high speed operations such as turning, grinding, or milling. Heavy lubricants work best for drilling, tapping, broaching or boring.The commonly used welding techniques work well with this alloy. It is not heat treatable, but can be annealed after cold working.