In the demanding worlds of chemical processing, offshore engineering, and energy generation, material failure is not an option. Equipment must withstand some of the most aggressive environments on earth, from concentrated acids to saline atmospheres. It is in these critical applications that Incoloy 825 (UNS N08825) proves its exceptional value as a high-performance nickel-iron-chromium alloy.
Incoloy 825 is a sophisticated alloy specifically designed to combat a wide spectrum of corrosive threats. The addition of titanium stabilizes the alloy against sensitization (precipitation of carbides at grain boundaries) during welding or exposure to high temperatures, preventing intergranular corrosion.
Incoloy Alloy 825 Sheets, Plates, Coils Specification
| Specifications | ASTM B424, ASME SB424 |
| Standards | ASTM, ASME and API |
| Size | 1000 mm x 2000 mm, 1220 mm x 2440 mm, 1500 mm x 3000 mm, 2000 mm x 2000 mm, 2000 mm x 4000 mm |
| Thickness | 0.1mm to 12 mm Thk |
| Length | 12500 mm |
| Form | Coils, Foils, Shim Sheet, Perforated Sheet, Chequered Plate, Strip, Flats, Blank (Circle), Ring (Flange) & Angle, Channel, Tray Etc. |
| Hardness | Soft, Hard, Half Hard, Quarter Hard, Spring Hard etc. |
| Plate, Sheet, and Strip | BS3072NA18 (Sheet and Plate), BS3073NA18 (Strip), QQ-N-286 (Plate, Sheet and Strip), DIN 17750 (Plate, Sheet and Strip), ISO 6208 (Plate, Sheet and Strip) |
| Ni | Fe | Cr | Mb | Cu | Ti | C | Mn | S | Si | Al |
| 38.0-46.0 | 22.0 min | 19.5-23.5 | 2.5-3.5 | 1.5-3.0 | .6-1.2 | 0.05 max | 1.0 max | 0.03 max | 0.5 max | 0.2 max |
Application of Incoloy 825 Nickel Alloy Sheet
- Oil and gas: submarine pipelines, downhole tools for acid gas wells.
- Chemical equipment: sulfuric acid reactors, phosphoric acid evaporators, pickling equipment.
- Nuclear industry: containers and pipelines for nuclear waste treatment systems.
- Marine engineering: seawater desalination devices, heat exchangers.
- Environmental protection: key components of flue gas desulfurization (FGD) systems.
Hot working
The recommended temperature range is 900℃-1175℃, and rapid cooling (water quenching) is required after hot forming to avoid carbide precipitation.
Cold working
It needs to be carried out in steps (single deformation ≤20%), and the intermediate annealing temperature is 980℃-1030℃ to eliminate work hardening.
Understanding Its Mechanical Properties and Limitations
Incoloy 825 offers robust mechanical properties across a wide temperature range, maintaining good strength and toughness from cryogenic levels up to moderately high temperatures. However, understanding its high-temperature limitations is crucial for safe and effective design.
Prolonged exposure to temperatures exceeding 1000°F (540°C) can lead to microstructural changes within the alloy, primarily the precipitation of secondary phases. This can result in a significant reduction in ductility and impact strength, embrittling the material. Consequently, Incoloy 825 is not recommended for applications where creep and rupture strength are primary design considerations. Engineers must carefully consider the service temperature and mechanical stresses when specifying this alloy for high-temperature duty.