Designated as UNS N08825 or DIN W.Nr. 2.4858, Incoloy 825 (also known as “Alloy 825”) is an iron-nickel-chromium alloy with additions of molybdenum, cooper and titanium. The molybdenum addition improves its resistance to pitting corrosion in aqueous corrosion application while copper content bestows resistance to sulfuric acid. Titanium is added for stabilization. The Alloy 825 has excellent resistance to both reducing and oxidizing acids, to stress-corrosion cracking, and to localized attack such as pitting and crevice corrosion. It is especially resistant to sulfuric and phosphoric acids. Incoloy 825 alloy is mainly used for chemical processing, petrochemical piping, pollution-control equipment, oil and gas well piping, nuclear fuel reprocessing, acid production, and pickling equipment.
1. Chemical Composition Requirements
| The Chemical Composition of Incoloy 825, % |
| Nickel |
38.0-46.0 |
| Iron |
≥22.0 |
| Chromium |
19.5-23.5 |
| Molybdenum |
2.5-3.5 |
| Copper |
1.5-3.0 |
| Titanium |
0.6-1.2 |
| Carbon |
≤0.05 |
| Manganese |
≤1.00 |
| Sulfur |
≤0.030 |
| Silicon |
≤0.50 |
| Aluminum |
≤0.20 |
2. Mechanical Properties of Incoloy 825
Incoloy 825 weld neck flanges 600# SCH80, manufactured to ASTM B564.
| Tensile Strength, min. |
Yield Strength, min. |
Elongation, min. |
Elastic Modulus |
| Mpa |
ksi |
Mpa |
ksi |
% |
Gpa |
106psi |
| 690 |
100 |
310 |
45 |
45 |
206 |
29.8 |
3. Physical Properties of Incoloy 825
| Density |
Melting Range |
Specific Heat |
Electrical Resistivity |
| g/cm3 |
°C |
°F |
J/kg.k |
Btu/lb. °F |
µΩ·m |
| 8.14 |
1370-1400 |
2500-2550 |
440 |
0.105 |
1130 |
4. Product Forms and Standards of Incoloy 825
| Product form |
Standard |
| Rods and bars |
ASTM B425, DIN17752 |
| Plates, sheet and strips |
ASTM B906, B424 |
| Seamless pipes and tubes |
ASTM B423, B829 |
| Welded pipes |
ASTM B705, B775 |
| Welded tubes |
ASTM B704, B751 |
| Welded pipe fittings |
ASTM A366 |
| Forging |
ASTM B564, DIN17754 |