Incoloy 825 (UNS N08825)

Incoloy 825 (also specified as UNS N08825 / Werkstoff No. 2.4858) is an austenitic nickel-iron-chromium alloy with molybdenum and copper additions, stabilised with titanium. It offers outstanding corrosion resistance in both oxidising and reducing media, excellent resistance to chloride stress-corrosion cracking, pitting and crevice corrosion, and good mechanical properties from room temperature up to about 550 °C. It is a first-choice material for sour-gas, sulfuric-acid and marine service.

Overview

• Category: Austenitic Ni-Fe-Cr-Mo-Cu corrosion-resistant alloy
• Standards: ASTM B163, B423, B424, B425, B564, B704, B705, B366, B751, B775, B829; UNS N08825; W.Nr. 2.4858
• Available forms: Round bar / rod, plate, sheet, pipe & tube, fittings, wire, forgings, and custom profiles to order

Chemical Composition (wt%)

Physical Properties

Mechanical Properties (typical, solution-annealed)

Good mechanical properties are retained from room temperature up to approximately 550 °C.

Fabrication & Welding

• Hot working: 1050–1200 °C with uniform heating; air cool or water cool after working.
• Cold working: Good cold-formability (cold rolling, cold drawing, stamping), with a moderate work-hardening rate.
• Welding: Good weldability by GTAW (TIG), electron-beam welding, resistance welding and other conventional processes. Preheat is generally not required, and post-weld heat treatment is normally unnecessary.

Heat Treatment

• Solution treatment: Heat to 1000–1100 °C and cool rapidly, to fully dissolve alloying elements into the matrix and maximise corrosion resistance and toughness.
• Note: Alloy 825 cannot be hardened by heat treatment.

Key Features

• Good corrosion resistance in both oxidising and reducing environments, including sulfuric, phosphoric and nitric acids and alkaline solutions;
• Excellent resistance to stress-corrosion cracking;
• Good pitting and crevice-corrosion resistance;
• Good high-temperature strength and oxidation resistance;
• Good fabricability into a wide range of components.

Corrosion Resistance

• Outstanding performance in sulfuric acid, phosphoric acid, sulfur-bearing flue gas, sour gas and oil-well environments, and seawater;
• Excellent resistance to pitting, crevice corrosion and stress-corrosion cracking in chloride environments;
• Good general corrosion resistance in both oxidising and non-oxidising acids.

Typical Applications

• Chemical processing: reaction vessels, heat exchangers, piping and valves;
• Oil & gas: oil-well tubing, subsea pipelines and oil / gas processing equipment;
• Pollution control: scrubbers and stack / chimney linings;
• Food engineering: food-processing equipment;
• Nuclear fuel handling: nuclear-fuel dissolvers and radioactive-waste treatment equipment.

For detailed datasheets, mill certificates (EN 10204 3.1) or inquiries on specific sizes and tolerances, please contact our sales & engineering team.