This is one of several high nickel chromium alloys of particular mention because of its combination of very high strength, excellent fabricability, and outstanding corrosion resistance. It also has a particularly useful temperature range from cryogenic to 950C.
Its strength is derived from the effects of the molybdenum and niobium on its nickel chromium structure. This combination of elements are also responsible for its superior resistance to a wide range of corrosive environments of unusual severity. These properties have made it an excellent choice for sea-water applications such as wire rope mooring cables and propeller blades for Naval vessels. Its thermal fatigue strength, oxidation resistance and excellent weld ability have made this alloy of interest for a variety of aerospace applications. Its high corrosion resistance and fabricability have also made it a favourite with the chemical industry for its plant and storage equipment.
In 625 will almost resist complete attack from sea-water, neutral salts and alkaline media, and will also resist such corrosive problems as hydrochloric and nitric acids.
Because of the high nickel (up to 60%) and chromium content of 625 it is hard to machine, and like all the high nickel chromium alloys the raw material is very expensive.