Incoloy 825, known as UNS N08825, is a nickel-iron-chromium alloy with additions of molybdenum and copper. It has excellent resistance to both reducing and oxidizing acids, stress-corrosion cracking, and localized attacks such as pitting and crevice corrosion. The alloy is especially resistant to sulfuric and phosphoric acids.
Applications of Incoloy 825:
Sulphuric acid piping and vessels
Phosphoric acid evaporators
Pickling tank heaters, pickling tanks, and equipment
Chemical process equipment
Propellor shafts
Tank trucks
Calorifiers
Electrostatic precipitator electrodes
Hot vessels for food, water, and seawater
Ammonium sulphate vessels
Expansion bellows
Marine exhaust systems
Power station ash hoppers
Normal product forms: Pipes, tubes, sheets, strips, plates, bars, forgings, and wires.
Specifications/Standard: ASTM B 163, B 366, B 423 – B 425, B 564, B 704, B 705, B 751, B 775, B 829, ASME SB-163, SB-366, SB-423 – SB-425, SB-564, SB-704, SB-705, SB-751, SB-775, SB-829, etc.
Nickel (Ni): 38.0 – 46.0%
Iron (Fe): 22.0% min
Chromium (Cr): 19.5 – 23.5%
Molybdenum (Mo): 2.5 – 3.5%
Copper (Cu): 1.5 – 3.0%
Titanium (Ti): 0.6 – 1.2%
Carbon (C): 0.05% max
Manganese (Mn): 1.0% max
Sulfur (S): 0.03% max
Silicon (Si): 0.5% max
Aluminum (Al): 0.2% max
Physical Constants and Thermal Properties
Density: 8.14 g/cm³
Melting range: 1370 – 1400 °C
Electrical conductivity: Volumetric, 1.5% IACS at 26 °C
Magnetic permeability: 1.005 at 21 °C and a field strength of 15.9 kA/m
Curie temperature: <–196 °C
Mechanical Property:
Incoloy 825 has good mechanical properties from cryogenic temperatures to moderately high temperatures.
Exposure to temperatures above about 1000°F (540°C) can result in microstructural changes (phase formation) that significantly lower ductility and impact strength.
