Alloy 925
Alloy 925 is an age-hardenable nickel-iron-chromium alloy with additions of molybdenum, copper, titanium and aluminium. The alloy's chemical composition is designed to provide a combination of high strength and excellent corrosion resistance. The nickel content provides protection against chloride-iron stress-corrosion cracking, and in combination with the molybdenum and the copper, also gives outstanding resistance to reducing chemicals. Molybdenum aids resistance to pitting and crevice corrosion, while chromium provides resistance to oxidizing environments. The addition of titanium and aluminium means that the alloy strengthens during heat treatment.
Alloy 925 is used in applications requiring high strength and corrosion resistance, and due it its resistance to sulphide stress cracking and stress-corrosion cracking in 'sour' crude oil and natural gas it is ideally suited to down-hole and surface gas-well components such as valves, hangers, nipples, tool joints and packers. It is also used for fasteners, marine and pump shafting and high-strength piping systems. It can also be used in environments containing sulphuric acid, phosphoric acid and seawater.
Maher stock this alloy in the solution annealed and aged condition to both national and customer specifications. National specifications include UNS NO9925 and NACE MR-0175, while material may also be released to customer specifications upon request.
Technical Data
Nominal Composition by Percent
| Ni | Cr | Fe | Mo | Cu | Ti | Al | Mn | Si | Nb | C | Su | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Min | 42.0 | 19.5 | 22.0 | 2.5 | 1.5 | 1.9 | 0.1 | - | - | - | - | - |
| Max | 46.0 | 22.5 | - | 3.5 | 3.0 | 2.4 | 0.5 | 1.0 | 0.5 | 0.5 | 0.03 | 0.03 |
Typical Mechanical Properties
| Solution Annealed and Aged Condition | PSI | MPa | % |
|---|---|---|---|
| Tensile Strength (min) | 167,000 |
1154 |
- |
| Yield Strength - 0.2% offset (min) | 120,600 |
832 |
- |
| Elongation in 2" (or 50mm) or 4D (min) | 27 |
- |
27 |
| Hardness Rockwell | 32 (HRC) |
- |
- |
Machining Alloy 925
Alloy 925 has good machinability in the solution annealed or aged conditions. Tools that minimise work hardening of the material during machining are required. Best results are obtained by rough machining before age hardening and finishing after heat treatment. Cemented carbide tools produce the highest cutting rates and are most suitable for turning operations involving uninterrupted cuts. For interrupted cuts, as well as finishing to close tolerances, smooth surfaces and minimal work hardening then high speed tool steels are preferred.