Alloy 925 (UNS N09925)
Description
Alloy 925 is an age-hardenable nickel-iron-chromium alloy that combines good high strength properties and excellent corrosion resistance. The addition of molybdenum and copper gives the alloy resistance to reducing chemicals, and to pitting and crevice corrosion. The high chromium content provides resistance to oxidizing conditions, while the nickel protects the alloy from chloride ion stress corrosion cracking. The alloy is made age-hardenable by the addition of aluminum and titanium.
This alloy is often chosen for liquid and gaseous applications where a combination of high strength and corrosion resistance is required. Alloy 925 provides excellent resistance to corrosion cracking caused by hydrogen sulfide in sour gas applications. Applications include down-hole and above ground components.
Chemical Composition
Chemical Composition (wt%) limits *
| Carbon | 0.03 | Manganese | 1.0 |
| Chromium | 19.5-22.5 | Silicon | 0.5 |
| Nickel | 42.0-46.0 | Copper | 1.5-3.0 |
| Iron | 22.0 min | Niobium | 0.5 |
| Molybdenum | 2.5-3.5 | Aluminum | 0.1-0.5 |
| Titanium | 1.9-2.4 | Sulfur | 0.03 |
*Maximum, unless range is indicated
Physical Properties
Physical properties for 925
| Density, lb/in3 | 0.292 |
| Modulus of Elasticity, psi | 28.9 x 106 |
| Coefficient of Thermal Expansion, 68-212˚F, /˚F | 7.8 x 10-6 |
| Thermal Conductivity, Btu/ft hr ˚F | 6.4 |
| Specific Heat, Btu/lb ˚F | 0.10 |
| Electrical Resistivity, Microhm-in | 46.1 |
Mechanical Properties
Mechanical properties of solution annealed and aged Alloy 925. Solution anneal at 1,800-1,900°F for 1 hour. Age harden at 1,365-1,380°F.
| Yield Strength, min. (ksi) | 120 |
| Tensile Strength, min. (ksi) | 170 |
| Elongation, min. (%) | 25 |
| Hardness, HRc | 32 |
Standards
Typical standards for Alloy 925
| NACE MRO175 |