Incoloy alloy 925 (UNS N09925) with the additions of molybdenum, copper, titanium and aluminium is an age hardenable nickel-iron-chromium alloy, providing a combination of high strength and excellent corrosion resistance. Sufficient nickel content provides protection against chloride-ion stress-corrosion cracking whilst in conjuncton with the added molybdenum and copper resistance to reducing chemicals is enjoyed. Molybdenum additionally aids resistance to pitting and crevice corrosion whilst Chromium offers resistance to oxidizing enviroments. During heat treatment a strengthening reaction is caused by the addition of titanium and aluminium.
Application requiring a combination of high strength and corrosion resistance may consider Incoloy alloy 925. Resistance to sulfide stress cracking and stress-corrosion cracking in "sour" crude oil and natural gas enviromments means that it is used for down-hole and surface gas-well components as well as finding uses in marine and pump shafts or high-strength piping systems.
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1. Chemical Composition Requirement
| The Chemical Composition of Incoloy 925, % |
| Nickel | 42.0-46.0 |
| Chromium | 19.5-22.5 |
| Iron | ≥22.0 |
| Molybdenum | 2.5-3.5 |
| Copper | 1.5-3.0 |
| Titanium | 1.9-2.4 |
| Alumium | 0.1-0.5 |
| Manganese | ≤1.00 |
| Silicon | ≤0.50 |
| Niobium | ≤0.50 |
| Carbon | ≤0.03 |
| Sulfur | ≤0.30
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2. Mechanical Properties of Incoloy 925
| Tensile Strength, min. | Yield Strength, min. | Elongation, min. | Hardness, min. |
| Mpa | ksi | Mpa | ksi | % | HRC |
| 1210 | 176 | 815 | 118 | 24 | 36.5 |
3. Physical Properties of Incoloy 925
| Density | Melting Range | Specific Heat | Electrical Resistivity |
| g/cm3 | °F | °C | J/kg.k | Btu/lb. °F | µΩ·m |
| 8.08 | 2392-2490 | 1311-1366 | 435 | 0.104 | 1166 |
4. Product Forms and Standards
| Product Form | Standard |
| Rod, bar & Wire | ASTM B805 |
| Plate, sheet & strip | ASTM B872 |
| Seamless pipe and tube | ASTM B983 |
| Forging | ASTM B637
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