06/11/2025
Alloy 825 (UNS N08825) Description
Alloy 825 is an austenitic nickel-iron-chromium-molybdenum-copper alloy containing high levels of chromium, nickel, molybdenum, and copper, providing a high level of corrosion resistance in moderately oxidizing and moderately reducing environments. Compared to standard stainless steel, this alloy has a high level of nickel, which, combined with the molybdenum and copper content, results in significantly improved corrosion resistance in reducing environments. The nickel content is high enough to provide good resistance to chloride stress corrosion cracking. The chromium and molybdenum content in the alloy provides a level of resistance to chloride pitting corrosion. Furthermore, the alloy is stabilized in the weld state to prevent sensitization by adding specific levels of titanium. Due to this stability,
Alloy 825 has a long history of use in many corrosive environments and has been incorporated into ASTM and ASME specifications for many years. As an austenitic nickel-based alloy, this material exhibits ductility over a wide temperature range, from low temperatures to over 1000°F (538°C).
Typical Standards for Alloy 825
ASTM B425
ASME SB425
Chemical Composition (wt%): (Limited to specifications in ASTM B425)
Carbon: ≤0.05
Manganese: ≤1.0
Chromium: 19.5-23.5
Silicon: ≤0.5
Nickel: 38.0-46.0
Copper: 1.5-3.0
Iron: ≥22.0
Aluminum: 0.1-0.5
Molybdenum: 2.5-3.5
Sulfur: ≤0.03
Titanium: 0.6-1.2
Physical Properties of Alloy 825
Density, psi: 0.293
Elastic Modulus, psi: 28.3 x 10⁶
Coefficient of Thermal Expansion, 68-212 µF, / µF: 7.7 x 10⁻⁶
Thermal Conductivity, Btu / fthr µF: 6.4
Specific Heat, Btu /lb?F: 0.12
Resistivity, Microhm-in: 44.5
Mechanical Properties: Mechanical properties required for annealed products according to ASTM B 425:
Yield Strength (KSI): ≥35
Tensile Strength (KSI): ≥85
Elongation (%): ≥30
Nickel Alloys: Due to their high versatility, nickel and nickel alloys are suitable for a wide range of applications, most of which involve corrosion resistance and/or heat resistance. These include: aircraft gas turbines, steam turbine power plants, medical applications, nuclear power systems, and the chemical and petrochemical industries. Nickel alloys also exhibit excellent heat and corrosion resistance.
