Incoloy 925 (UNS N09925) is an age-hardenable nickel-iron-chromium alloy designed for the combination of high strength, excellent chloride stress-corrosion cracking resistance and qualified sour-service performance. The alloy combines the corrosion envelope of solid-solution Incoloy 825 with strength approaching Inconel 718, making it the standard choice for downhole completion equipment, surface safety valves, tool joints, hangers and the bolting that holds them together. This datasheet aggregates the limiting values codified in ASTM B805 (bar/forgings), ASTM B983 (plate/sheet/strip), API 6A (wellhead PSL-1/2/3/4) and NACE MR0175 / ISO 15156-3 (sour service). Source: Special Metals Corporation INCOLOY® alloy 925 Technical Bulletin.
Need Incoloy 925 with full MTC? Email info@torqbolt.com with product type, size, quantity and applicable standards. Every order ships with EN 10204 3.1 manufacturer's MTC documenting actual heat-lot values vs the limits below; EN 10204 3.2 third-party witnessed certification on request. WhatsApp +91-22-66157017.
1. Limiting Chemical Composition (UNS N09925)
| Element | Min % | Max % | Role |
|---|---|---|---|
| Nickel (Ni) | 42.0 | 46.0 | Cl-SCC resistance, austenite stabiliser |
| Chromium (Cr) | 19.5 | 22.5 | oxidising-environment passivation |
| Iron (Fe) | 22 min | balance | matrix base |
| Molybdenum (Mo) | 2.5 | 3.5 | pitting / sour-service performance |
| Copper (Cu) | 1.5 | 3.0 | reducing-acid resistance |
| Titanium (Ti) | 1.9 | 2.4 | gamma-prime former (age hardening) |
| Aluminum (Al) | 0.1 | 0.5 | gamma-prime former (age hardening) |
| Manganese (Mn) | 1.0 max | deoxidiser, residual | |
| Silicon (Si) | 0.5 max | deoxidiser, residual | |
| Niobium (Nb) | 0.5 max | residual / carbide former | |
| Carbon (C) | 0.03 max | limits M₂₃C₆ precipitation | |
| Sulfur (S) | 0.03 max | limits hot-cracking |
Source: Special Metals Technical Bulletin Table 1 / SMC HA 46. See full chemical composition page for element-by-element commentary, comparison vs adjacent alloys and trademark/UNS naming.
2. Mechanical Property Limits
| Condition | UTS, ksi (MPa) min | 0.2% YS, ksi (MPa) min | Elong, % min | RA, % min | Hardness, HRC max |
|---|---|---|---|---|---|
| Annealed (1900°F WQ) | 110 (760) | 50 (345) | 30 | 40 | 32 |
| Annealed + Aged | 165 (1140) | 110 (760) | 18 | 25 | 35 |
Charpy V-Notch Impact (aged): 40 J min at -46°C (NACE MR0175 sour-service); 27 J min at -101°C (API 6A PSL-3G). See full mechanical properties page for elevated-temperature data, alloy comparison and Charpy envelope.
3. Physical Properties (Aged Condition, 20°C)
- Density: 8.08 g/cm³ (0.292 lb/in³)
- Modulus of Elasticity: 27.6 × 10⁶ psi (190 GPa)
- Poisson's Ratio: 0.30
- Thermal Conductivity: 11.0 W/m·K at 20°C
- Specific Heat: 444 J/kg·K at 20°C
- Coefficient of Thermal Expansion (21–93°C): 12.6 × 10⁻⁶ /°C (7.0 × 10⁻⁶ /°F)
- Magnetic Permeability: 1.005–1.05 (essentially non-magnetic)
- Electrical Resistivity: 1.14 μΩ·m at 20°C
- Melting Range: 1357–1399°C (2475–2550°F)
See full physical properties page for elevated-temperature data, comparison vs adjacent alloys and FEA design notes.
4. Heat Treatment
| Cycle | Temperature | Hold Time | Cool |
|---|---|---|---|
| Solution Anneal | 1900°F (1040°C) | 1 h per inch (min 1 h) | Water Quench |
| Age (Step 1) | 1365°F (740°C) | 8 h | Furnace cool 100°F/h to 1150°F |
| Age (Step 2, optional) | 1150°F (621°C) | 8 h | Air Cool |
The two-step ageing cycle precipitates Ni₃(Al, Ti) gamma-prime particles that double yield strength. See full heat treatment page for furnace charge density limits, atmosphere requirements and quench sensitivity data.
5. Sour-Service Qualification
Incoloy 925 is listed in NACE MR0175 / ISO 15156-3 Table A.10 for sour-service oil and gas applications. The qualified envelope:
| Parameter | Qualified Range |
|---|---|
| H₂S Partial Pressure | up to 1000 psi (6.9 MPa) |
| Maximum Temperature | 400°F (204°C) |
| Chloride Concentration | up to saturation |
| Maximum Hardness (CW + Aged) | 35 HRC |
| Sulfur Content | any (no S restriction) |
| API 6A Material Class | FF / HH (sour) — qualified for PSL 1/2/3/3G/4 |
6. Welding
Incoloy 925 is welded with matching-composition filler INCO-WELD® alloy 725NDUR (UNS N07725) or solid-solution INCONEL® Filler Metal 625 (UNS N06625). Process options include GTAW, SMAW, GMAW and SAW. Post-weld solution anneal + age recommended for full property recovery. See full welding procedure page for filler selection, preheat / interpass guidance and post-weld heat treatment cycles.
7. Standards Compliance
| Standard | Scope | Coverage |
|---|---|---|
| ASTM B805 | Forgings & forging stock | Bar, billet, forging |
| ASTM B983 | Plate, sheet & strip | Hot/cold rolled flat product |
| API 6A | Wellhead & Christmas tree equipment | PSL-1/2/3/3G/4 bolting + bodies |
| NACE MR0175 | Sour-service materials | Table A.10 nickel alloys |
| ISO 15156-3 | Sour-service materials (ISO) | Annex B nickel alloys |
| EN 10204 | Inspection certification | 3.1 (manufacturer) / 3.2 (TPI) |
| NORSOK M-630 | Material data sheet (Norway) | MDS A30 / N09925 |
8. Available Product Forms
| Form | Standard | Size Range | Application |
|---|---|---|---|
| Stud Bolts | ASTM B805 / API 6A | 1/4" to 4" | Wellhead, Christmas tree, sour service |
| Heavy Hex Nuts | ASTM B805 / ASME B18.2.4.6M | M6 to M64 | Companion to stud bolts |
| Hex Bolts | ASTM B805 / ASME B18.2.1 | 1/4" to 2" | Structural, flange bolting |
| Washers | ASTM B805 | 1/4" to 3" | Load distribution |
| Pipe | ASTM B983 | 1/2" to 12" NPS | Sour-service flowlines |
| Plate & Sheet | ASTM B983 | 3 mm to 50 mm thk | Pressure vessels, cladding |
9. Typical Applications
- Down-hole gas-well completion equipment, tubing hangers, packers, landing nipples
- Surface safety valves (SSV) and subsurface safety valves (SSSV), bodies and bolting
- Drill string tool joints in sour service
- Tubing/casing hangers for HPHT wellheads
- General sour-service oil & gas components
- Marine and offshore structural fasteners
- High-strength piping systems and pump shafting
- MWD/LWD downhole tool housings (low magnetic permeability)
10. Frequently Asked Questions
What is the difference between Incoloy 925 in annealed vs aged condition? The annealed condition (1900°F WQ) gives ~110 ksi UTS / 50 ksi YS with high ductility, suitable for forming and welding. The aged condition (annealed + 1365°F × 8h) precipitates gamma-prime that lifts properties to 165 ksi UTS / 110 ksi YS minimum, the values codified in ASTM B805 and required by API 6A. Almost all production fasteners ship in the aged condition.
How is sour-service compliance verified? The MTC must (1) certify chemistry within UNS N09925 limits, (2) certify hardness ≤35 HRC in the aged condition, (3) reference NACE MR0175 Table A.10 / ISO 15156-3 Annex B. Optional: include sample-coupon test data per NACE TM0177 Method A (tensile in H₂S) or TM0316 (4-point bend). Specify "NACE-stamped MTC" at RFQ stage.
Can Incoloy 925 be used at cryogenic temperatures? Yes. The alloy retains good toughness down to -196°C (LNG service temperature) per API 6A PSL-3G material toughness requirements. Charpy testing at -101°C is standard; -196°C testing on request.
What's the price premium vs Incoloy 825? Incoloy 925 is approximately 1.5–2× the price of Incoloy 825 for the same product form, reflecting the additional Ti, the controlled ageing cycle, and the higher mechanical-test envelope. The premium is justified when API 6A wellhead bolting strength is required, 825 cannot meet 110 ksi YS even cold-worked.
How does TorqBolt manufacture Incoloy 925? Bar/forging stock procured from approved primary mills (Special Metals, Sandvik, VDM, ATI) with mill MTC documenting heat chemistry. TorqBolt performs cold/hot forming, threading, controlled ageing in calibrated furnaces, and final NDE (PT/UT/RT as specified). Every batch tested per ASTM E8 (tensile), E18 (hardness), E23 (Charpy), with results consolidated on EN 10204 3.1 MTC.
11. Request a Quote
For Incoloy 925 with full MTC documentation:
- Email: info@torqbolt.com
- WhatsApp: +91-22-66157017
- Datasheet PDF + sample MTC available on request
Specify product type (stud bolts, nuts, hex bolts, washers, pipe, plate), size range, quantity, applicable standards (ASTM B805, ASTM B983, API 6A, NACE MR0175), required condition (annealed or aged), and any special test requirements (Charpy temperature, third-party witness, NACE TM test data).
12. Source & References
Special Metals Corporation: INCOLOY® alloy 925 Technical Bulletin, Tables 1, 4, 5, 6, 7, 8, 9, 10, 12, 13. ASTM B805 Standard Specification for Forgings and Forging Stock for Nuclear and General Use Wrought Precipitation Hardened UNS N09925. ASTM B983 Standard Specification for Precipitation Hardened UNS N09925 Plate, Sheet, and Strip. API Specification 6A Wellhead and Tree Equipment. NACE MR0175 / ISO 15156-3 Petroleum and Natural Gas Industries, Materials for use in H₂S-containing environments. EN 10204 Metallic Products, Types of Inspection Documents. INCOLOY®, INCONEL® and INCO-WELD® are registered trademarks of Special Metals Corporation.
