INCOLOY 825 (UNS N08825 / NS142)

Alloy 825 is an austenitic nickel-iron-chromium alloy also defined by additions of molybdenum, copper and titanium. It was developed to provide exceptional resistance to numerous corrosive environments, both oxidizing and reducing.

 Alloy 825 was developed to provide exceptional resistance to numerous corrosive environments, both oxidizing and reducing. With a nickel content range between 38%–46%, this grade exhibits pronounced resistance to stress corrosion cracking (SCC) induced by chlorides and alkalis. The nickel content is sufficient for resistance to chloride-ion stress-corrosion cracking. The nickel, in conjunction with the molybdenum and copper, also gives outstanding resistance to reducing environments such as those containing sulfuric and phosphoric acids.

The chromium and molybdenum content also provides good pitting resistance in all environments except strongly oxidizing chloride solutions. Utilized as an effective material in a wide variety of process environments, alloy 825 maintains good mechanical properties from cryogenic temperatures up to 1,000° F.

The addition of titanium stabilizes Alloy 825 against sensitization in the as- welded condition making the alloy resistant to intergranular attack after exposure to temperatures in a range that would sensitize unstabilized stainless steels. The fabrication of Alloy 825 is typical of nickel-base alloys, with material being readily formable and weldable by a variety of techniques.

This material has excellent formability, typical of nickel-base alloys, allowing the material to be bent to extremely small radii. Annealing after bending is not normally necessary.

It is similar to alloy 800 but has improved resistance to aqueous corrosion. It has excellent resistance to both reducing and oxidizing acids, to stress-corrosion cracking, and to localized attack such as pitting and crevice corrosion. Alloy 825 is especially resistant to sulfuric and phosphoric acids. This nickel steel alloy is used for chemical processing, pollution-control equipment, oil and gas well piping, nuclear fuel reprocessing, acid production, and pickling equipment.