Alloy 825 is a nickel-chromium-iron solid solution strengthened alloy with a nominal chemical composition of 42% nickel, 21% chromium, and 22% iron, plus additions of molybdenum, titanium, and copper. It is commonly referred to by the tradename Incoloy® 825 and the universal designation UNS N08825.

Corrosion Resistance

Alloy 825 has good corrosion resistance in many environments, including reducing and oxidizing acids, organic acids, seawater, salts, and alkalis. It is particularly resistant to sulfuric and phosphoric acids. The molybdenum addition gives Alloy 825 good resistance to chloride-induced localized corrosion, including pitting, crevice corrosion, and stress corrosion cracking. Additionally, alloy 825 has good oxidation resistance.

Service Temperature

Alloy 825 is used at temperatures from cryogenic up to 1000°F (540°C). The use of Alloy 825 at temperatures above 1000°F (538°C) is not recommended as harmful phases can form with a negative effect on impact toughness and ductility.

Mechanical Properties

Alloy 825 can be provided in the annealed condition or strengthened through the pilger process. Alloy 825 maintains useful mechanical properties up to about 1000°F (538°C) and good toughness down to cryogenic temperatures.

Heat Treatment

Alloy 825 cannot be strengthened by heat treatment. For elevated temperature applications or where the product is to be welded, a stabilization anneal around 1725°F (940°C) is recommended. At this temperature, the carbon is tied up as titanium carbides. This prevents precipitation of chromium carbides at the grain boundaries (i.e., sensitization) from occurring in service or during welding. For optimum toughness and ductility, a higher temperature anneal may be performed.

Workability

Alloy 825 is friendly to both hot working and cold working.

Incoloy 825 Pipes Fitting Equivalent Grade

Incoloy 825 Pipes Fitting Chemical Composition

Alloy 825 Pipes Fitting Mechanical Properties