Specifications
| BS 3076 NA16 | 2.4858 | NFe 32 C 20 DU |
| NiCr 21 Mo | ASTM B425 | UNS N08825 |
| API 6CRA 825 15156-3 | – | – |
Alloy 825
Alloy 825 is a nickel-iron-chromium alloy with additions of molybdenum, copper and titanium. It has good mechanical properties from cryogenic to medium-high temperatures (5400C) and can be strengthened through cold working. These alloys are designed for excellent corrosion resistance and strength at high temperatures, Alloy 825 was introduced in 1952 to better resist sulphuric acid. It has copper additions, nickel, chromium, and molybdenum additions to improve resistance to reducing and oxidising environments.
Chemical Composition Limits
| Â | Cr | Ni | Mo | Co | Nb (+Ta) | Ti | W | Cu | C | Mn | N | Si | P | S | Fe | Al |
| Min | 19.50 | 38.00 | 2.50 | – | – | 0.60 | – | 1.50 | – | – | – | – | – | – | 22.00 | – |
| Max | 23.50 | 46.00 | 3.50 | – | – | 1.20 | – | 3.00 | 0.05 | 1.00 | – | 0.50 | – | 0.03 | – | 0.20 |
Mechanical Properties
| 0.2% Proof Stress | 241 N/mm2 | 35 ksi |
| Tensile Strength | 590 N/mm2 | 86 ksi |
| Elongation, 5.65√S0 and 4D | 30% | – |
| Reduction of Area | 40% | – |
| Hardness (Brinell) | 327 max. | – |
Physical Properties
| Density (Kg.m-1) | 81.4 |
| Magnetic Permeability (20°C) | 1.005 |
| Curie Temperature (°C) | -196 |
| Young’s Modulus (N/mm2) | 196 |
| Specific Heat, 20°C (J/(g.K)) | 440 |
| Specific Electrical Resistance, 20°C (Ω-m) | 0.00113 |
| Thermal conductivity, 20°C (W/(m.K)) | 10.8 |
| Mean coefficient of thermal expansion, 20-100°C (/K) | 14.1 x 10-6 |
Key Features
- Excellent corrosion resistance in a wide variety of corrosive environments including seawater and industrial acids.
- Readily formable and weldable.
- Excellent resistance to stress corrosion cracking.
Applications
- Chemical process equipment.
- Pollution control systems and wet scrubbers.
- Waste heat recovery exchangers.
- Tanks, vessels and agitators.
- Downhole equipment for corrosive/sour service.
- Nuclear reprocessing and handling.