Alloy 925 ForgingsUNS N09925 · ASTM B564 · NACE MR0175 / ISO 15156-3
Alloy 925 (UNS N09925) is an age-hardenable nickel-iron-chromium alloy with molybdenum, copper, titanium and aluminium additions, used where a component needs the corrosion resistance of Alloy 825 at roughly three times the yield strength. Jiangyin Jiangnan Metal Co., Ltd., an open-die forging factory in Jiangyin, Jiangsu, China, forges it into seamless rolled rings, flanges, shafts, discs, sleeves and tube sheets for sour oil and gas, subsea and marine service.
Send a drawing and the quotation will set out the forging route, the machining allowance, the test plan and the price.
What Alloy 925 is, and when to specify it
Alloy 925 is an austenitic nickel-iron-chromium alloy made precipitation-hardenable by titanium and aluminium additions. During ageing, gamma-prime Ni3(Al,Ti) precipitates form throughout the matrix and sharply raise hardness and strength. The alloy is designated UNS N09925 and is widely known by the trade name Incoloy® 925.
Each addition does a specific job. Nickel protects against chloride-ion stress-corrosion cracking. Nickel with molybdenum and copper resists reducing chemicals. Molybdenum adds pitting and crevice resistance. Chromium handles oxidising conditions. Titanium and aluminium provide the strengthening.
Alloy 925 suits parts that have to carry load in a sour well. It resists sulphide stress cracking and stress-corrosion cracking in H2S-bearing crude oil and natural gas, and it holds a substantial part of its room-temperature strength up to about 650 °C (1200 °F). If the part only needs corrosion resistance and not strength, Alloy 825 is cheaper. If it needs more strength than 925 can give, look at Alloy 725 or 945.
Technical data on this page is consolidated from the Special Metals Corporation technical bulletin for INCOLOY alloy 925 (publication SMC-070) and the governing ASTM, NACE/ISO and API standards. View the source bulletin. The mill test certificate supplied with each order governs.
Chemical composition of Alloy 925
| Element | Symbol | Weight % | Role in the alloy |
|---|---|---|---|
| Nickel | Ni | 42.0 – 46.0 | Resistance to chloride stress-corrosion cracking |
| Chromium | Cr | 19.5 – 22.5 | Resistance in oxidising environments |
| Iron | Fe | 22.0 min | Balance of the matrix |
| Molybdenum | Mo | 2.5 – 3.5 | Pitting and crevice corrosion resistance |
| Copper | Cu | 1.5 – 3.0 | Resistance to reducing acids |
| Titanium | Ti | 1.9 – 2.4 | Gamma-prime former, age hardening |
| Aluminium | Al | 0.10 – 0.50 | Gamma-prime former, age hardening |
| Manganese | Mn | 1.0 max | Deoxidiser, sulphur control |
| Silicon | Si | 0.5 max | Deoxidiser |
| Niobium | Nb | 0.5 max | Residual |
| Carbon | C | 0.03 max | Held low to limit carbide precipitation |
| Sulphur | S | 0.03 max | Held low for hot workability |
Limits above follow the proprietary UNS N09925 limiting composition. ASTM B564 and ASTM B805 permit slightly wider bands for some elements: nickel down to 38.0 % and chromium up to 23.5 %. Always order against a named specification and edition. Melting practice for our forging stock is EAF + VOD, or EAF + VOD + ESR where the specification calls for remelted material.
Mechanical properties of Alloy 925 forgings
The values below are specification minimums for solution-annealed and aged material, that is, what a forging is accepted against rather than typical test results. Hot-worked limits apply to forgings; cold-worked limits are shown for comparison with bar and tube.
| Condition | Section | Tensile, min | 0.2 % yield, min | Elong. min | R of A min | Charpy V min | Hardness |
|---|---|---|---|---|---|---|---|
| Hot worked (forgings) | 25.4 – 254 mm 1 – 10 in |
965 MPa 140 ksi |
758 MPa 110 ksi |
18 % | 25 % | 47 J 35 ft·lbf |
26 – 38 HRC |
| Cold worked | 15.9 – 76.2 mm 5/8 – 3 in |
965 MPa 140 ksi |
724 MPa 105 ksi |
18 % | 25 % | 47 J 35 ft·lbf |
26 – 38 HRC |
Charpy V-notch tests are performed at −60 °C (−75 °F) to ASTM E23; hardness to ASTM E18. Where a project specification such as API 6A CRA or a customer standard sets different acceptance values, we forge and heat treat to that specification instead.
| Condition | Tensile strength | 0.2 % yield strength | Elongation | Hardness |
|---|---|---|---|---|
| Solution annealed | 685 MPa (99.3 ksi) | 271 MPa (39.3 ksi) | 56 % | 76 HRB |
| Solution annealed + aged | 1154 MPa (167.3 ksi) | 832 MPa (120.6 ksi) | 27 % | 32 HRC |
Typical values, not guaranteed minimums. Yield strength roughly triples between the annealed and the aged condition.
Physical properties of Alloy 925
| Property | Metric | Imperial |
|---|---|---|
| Density | 8.08 g/cm³ | 0.292 lb/in³ |
| Melting range | 1311 – 1366 °C | 2392 – 2490 °F |
| Young's modulus (21 °C) | 199 GPa | 28.9 × 10³ ksi |
| Shear modulus (21 °C) | 77 GPa | 11.2 × 10³ ksi |
| Poisson's ratio | 0.293 | n/a |
| Electrical resistivity | 1.17 µΩ·m | 701 Ω·cmil/ft |
| Magnetic permeability (15.9 kA/m) | 1.001 | n/a |
| Specific heat (20 °C) | 435 J/kg·°C | 0.104 Btu/lb·°F |
| Mean coefficient of expansion (to 100 °C) | 13.2 µm/m·°C | 7.8 × 10⁻⁶ in/in·°F |
| Useful strength retained to | ≈ 650 °C | ≈ 1200 °F |
Hot working and heat treatment
The processing windows for Alloy 925 are narrow. Forging too cold causes cracking; finishing too hot costs both ageing response and corrosion resistance. The scale below maps each window onto the incandescence colours seen at the press.
Processing windows on the incandescence scale, 550 – 1250 °C
Why the two forging bands overlap: the alloy can be worked anywhere from 870 to 1175 °C, but for maximum corrosion resistance and the highest strength after direct ageing, the final reduction should land in the narrower 870–980 °C window. Up to about 1095 °C its hot-working behaviour is similar to Alloy 825.
| Operation | Temperature | Time | Cooling |
|---|---|---|---|
| Hot working | 870 – 1175 °C 1600 – 2150 °F |
As required | Finish reduction at 870 – 980 °C for best corrosion resistance and direct-age strength |
| Solution anneal | 980 – 1040 °C 1800 – 1900 °F |
30 min – 4 h | Air cool or faster up to 25 mm section; water quench all sections over 25 mm |
| Age, first step | 732 – 749 °C 1350 – 1380 °F |
6 – 9 h | Furnace cool to 621 °C |
| Age, second step | 621 °C ± 8 °C 1150 °F ± 15 °F |
To 18 h total ageing | Air cool or faster |
Prolonged exposure at elevated temperature can precipitate eta and sigma phases alongside gamma prime, which reduces impact strength. That is one reason ageing time and temperature are held to a tight band and recorded on the certificate.
Alloy 925 forged product forms we make
Seamless rolled rings
Ring-rolled to reduce input weight and give circumferential grain flow. The usual route for bearing races, casing hangers and body rings.
Forged flanges
Weld neck, slip-on, blind and special bore flanges to ASME B16.5, B16.47 or drawing.
Shafts & spindles
Stepped pump and compressor shafts, eccentric shafts, spindles and stems, upset or drawn from ingot.
Discs, disks & blanks
Upset discs and gear blanks with radial grain flow, rough machined or contour forged near net.
Sleeves & bushings
Hollow forged and bored sleeves, bushings and liners, including trepanned hollows to save material.
Tube sheets & blocks
Forged tube sheets for shell-and-tube exchangers, valve blocks, bodies and rectangular blanks.
Also produced in Alloy 925: round bar, forged pipe and tube, nozzles, valve seat rings, valve stems, manifolds, crankshafts, forged rolls and near-net open-die blanks to customer drawings. See also our forging disks, forged spindles and forging rolls.
Size range
Confirm against your drawing. These are the outer envelopes, not every combination.
| Form | Outside diameter / length | Wall / thickness | Single-piece weight |
|---|---|---|---|
| Seamless rolled rings | OD 200–3000 mm | 30–400 mm | up to 5000 kg |
| Flanges | OD 100–2500 mm | 20–350 mm | up to 3000 kg |
| Shafts & bars | Ø 80–800 mm, L ≤ 8000 mm | n/a | up to 6000 kg |
| Discs & tube sheets | Ø 200–2200 mm | 40–500 mm | up to 4000 kg |
Minimum order: 1 piece for trial, no MOQ by weight. Typical lead time: 30–45 days after drawing approval, subject to melt availability.
Manufacturing route for Alloy 925 forgings
- MELT
Melting
EAF + VOD, with ESR remelting where the specification requires it. Full heat traceability from the ingot.
- FORGE
Open-die forging
Upset and draw or ring roll at 870–1175 °C, finishing at 870–980 °C to protect corrosion resistance.
- HEAT TREAT
Solution + double age
980–1040 °C solution anneal, water quench over 25 mm, then 732–749 °C and 621 °C ageing, charted and recorded.
- MACHINE
Rough machining
Rough machined before ageing and finished after, since the aged alloy is markedly harder to cut.
- TEST
Testing & NDT
Tensile, Charpy at −60 °C, hardness survey, PMI and ultrasonic testing to EN 10228-3, SEP 1921 or ASTM A388.
- CERTIFY
Certification & despatch
EN 10204 3.1 mill certificate, or 3.2 witnessed by a third party such as BV, SGS, TÜV or Lloyd's.
Applications for Alloy 925 forgings
Downhole oil & gas
Packers, landing nipples, tool joints, tubular components, safety valves and fasteners in sour wells. This is the principal market for the alloy.
Wellhead & Christmas tree
Casing and tubing hangers, valve bodies and seat rings, stems, bonnets and body rings to API 6A CRA.
Subsea & offshore
Subsea and deepwater production hardware, connectors, and components exposed to both seawater and produced fluids.
Pumps & compressors
Pump shafting in marine environments, plunger and chemical pump shafts, compressor components, gear blanks and couplings.
Pressure equipment
Forged flanges, tube sheets, shells and nozzles for heat exchangers, air receivers, columns, towers and pressure vessels.
Chemical process
Duty in sulphuric and phosphoric acid service, seawater handling, and mixed reducing/oxidising process streams.
Valves & flow control
Ball, gate, globe, check and plug valve bodies, blocks, stems and seat rings for corrosive and sour duty.
Marine & power
High-strength piping systems, marine shafting, and power transmission components where seawater corrosion drives the material choice.
Corrosion behaviour in service environments
Alloy 925 resists general corrosion, pitting, crevice corrosion, intergranular attack and stress-corrosion cracking in both reducing and oxidising environments. It is particularly useful in sour crude oil and natural gas, sulphuric acid, phosphoric acid and seawater.
| Environment | Temperature | Corrosion rate |
|---|---|---|
| 0.2 % hydrochloric acid | Boiling | < 0.01 mm/a (< 0.1 mpy) |
| 10 % sulphuric acid | 70 °C | 0.05 mm/a (2 mpy) |
| 85 % phosphoric acid | 90 °C | < 0.03 mm/a (< 1 mpy) |
| 80 % acetic acid | Boiling | < 0.01 mm/a (< 0.1 mpy) |
| 3.5 % sodium chloride, 1000 h crevice test | 25 °C | < 0.03 mm/a, no crevice attack |
Laboratory data, published by the alloy originator, for orientation only. Sour-service suitability must be established against ANSI/NACE MR0175 / ISO 15156-3 for the specific partial pressure of H2S, chloride content, pH and temperature of your service envelope, not from a general corrosion table.
Alloy 925 compared with 825, 718, 725 and K-500
| Alloy | UNS | Strengthening | Typical min. yield | Chosen when |
|---|---|---|---|---|
| Alloy 925 | N09925 | Age hardened, γ′ Ni₃(Al,Ti) | 758 MPa (110 ksi) | You need 825-grade corrosion resistance with high strength in sour service |
| Alloy 825 | N08825 | Solution annealed only | 241 MPa (35 ksi) | Corrosion resistance is the whole requirement and load is modest |
| Alloy 718 | N07718 | Age hardened, γ″ Ni₃Nb | 827 MPa (120 ksi) | Higher strength is needed and the API 6A718 route suits the part |
| Alloy 725 | N07725 | Age hardened, γ″ | 827 MPa (120 ksi) | Both higher strength and better corrosion resistance than 925 are required |
| Monel K-500 | N05500 | Age hardened, γ′ | 690 MPa (100 ksi) | Seawater and hydrofluoric service dominate over sour gas |
Yield figures are indicative specification minimums for common conditions and vary by product form, section size and governing specification. In autoclave C-ring testing, Alloy 925 in the age-hardened condition passed 42-day sulphide stress cracking tests at 38 HRC, and it separates from Alloy 825 mainly on strength rather than corrosion resistance. Sour-service acceptance for every grade is set by ANSI/NACE MR0175 / ISO 15156-3.
Welding and machining Alloy 925
Welding
Gas tungsten arc welding (GTAW) and gas metal arc welding (GMAW) are the preferred processes. An Alloy 725 type filler metal is normally recommended over matching 925 composition wire because it gives higher strength and better corrosion resistance in the deposit. With GMAW, keep current below about 180 A in spray transfer on standard power sources. Submerged arc welding and shielded metal arc welding are not recommended. For best thermal stability, solution anneal before welding and re-anneal plus age afterwards. Post-weld anneal-plus-age gives roughly double the weld Charpy energy of ageing alone.
Machining
The alloy machines reasonably at about 80 HRB in the solution-annealed condition and is considerably harder at up to 40 HRC after ageing, so the normal practice is rough machine before ageing and finish machine after. Use rigid set-ups and positive rake angles, cemented carbide for uninterrupted cuts and high-speed steel for interrupted cuts and fine finishing. As a rule of thumb, slower surface speeds with heavier chip loads remove metal best. Thin-walled trepanned sections can move after machining; a 621 °C / 2 h stress relief after trepanning substantially reduces run-out during subsequent turning.
Testing, inspection and certification
| Test | Standard | Notes |
|---|---|---|
| Chemical analysis | ASTM E1473 / spectrometer | Product analysis on request in addition to heat analysis |
| Tensile test | ASTM A370 / ASTM E8 | Room temperature; elevated temperature on request |
| Charpy V-notch impact | ASTM E23 | Standard test temperature −60 °C |
| Hardness | ASTM E18 | 26–38 HRC acceptance; full survey for sour service |
| Ultrasonic testing | EN 10228-3 · SEP 1921 · ASTM A388 | Acceptance class agreed at order stage |
| Grain size | ASTM E112 | Typically ASTM 2 or finer, equiaxed |
| Positive material identification | Handheld XRF | Piece-by-piece PMI on request |
| Liquid penetrant / magnetic particle | ASTM E165 | Penetrant only, since the alloy is non-magnetic |
| Certification | EN 10204 3.1 or 3.2 | 3.2 witnessed by BV, SGS, TÜV, Lloyd's or your own inspector |
Quality system: list your certifications here, for example ISO 9001:2015, PED 2014/68/EU, API 6A licence. Third-party witness inspection is welcome at any hold point.
How to order Alloy 925 forgings
We can price an enquiry quickly when it is complete. Please send:
- Drawing or dimensions, including the machining allowance you expect. If you give the finished size we will add the allowance.
- Quantity, and whether this is a prototype, a repeat order or a call-off.
- Delivery condition: as forged, rough machined, or finish machined and aged.
- Governing specification, for example ASTM B564, NACE MR0175 / ISO 15156-3, API 6A CRA, or your own company standard.
- Test and NDT requirements: tensile, impact temperature, hardness survey, UT class, PMI.
- Certification level: EN 10204 3.1, or 3.2 with the inspection body named.
Alloy 925 frequently asked questions
What is Alloy 925?
Alloy 925 is an age-hardenable austenitic nickel-iron-chromium alloy with molybdenum, copper, titanium and aluminium additions, designated UNS N09925. Titanium and aluminium form gamma-prime Ni3(Al,Ti) precipitates during ageing, which raise strength far above solution-annealed nickel alloys, while nickel, chromium, molybdenum and copper preserve resistance to chloride stress-corrosion cracking, pitting and reducing acids.
What is the UNS number for Alloy 925?
UNS N09925. It is also sold as Incoloy® 925, a registered trademark of Special Metals Corporation. Some traders list it as "Inconel 925", which is not a correct designation. If you see it on an offer, confirm the UNS number before you buy.
Is Alloy 925 the same as Incoloy 825?
No. They have comparable corrosion resistance in many environments, but Alloy 825 (UNS N08825) is supplied solution annealed and is not precipitation hardenable, with a typical minimum yield strength around 241 MPa. Alloy 925 adds titanium and aluminium so it can be age hardened to a minimum yield of 758 MPa in the hot-worked condition. Choose 925 when you want 825's corrosion behaviour at roughly three times the yield strength.
What is the maximum hardness for Alloy 925 in sour service?
The commonly applied acceptance band for solution-annealed and aged material is 26 HRC minimum to 38 HRC maximum, tested to ASTM E18. Sour-service acceptance itself is governed by ANSI/NACE MR0175 / ISO 15156-3, which sets the qualifying condition and environmental limits for UNS N09925. The applicable edition of that standard and your purchase order always govern over any supplier datasheet.
What heat treatment is used for Alloy 925 forgings?
Solution anneal at 980–1040 °C for 30 minutes to 4 hours. Air cool or faster up to 25 mm section, water quench everything over 25 mm. Then double age: 732–749 °C for 6–9 hours, furnace cool to 621 °C, hold at 621 °C ± 8 °C to a total ageing time of 18 hours, then air cool or faster.
What is the density and melting range of Alloy 925?
Density is 8.08 g/cm³ (0.292 lb/in³). Melting range is 1311–1366 °C (2392–2490 °F). Room-temperature Young's modulus is about 199 GPa and electrical resistivity is 1.17 µΩ·m.
Which standards cover Alloy 925 forgings?
Forgings are normally ordered to ASTM B564, with ASTM B805 covering wrought bar. Sour-service qualification follows ANSI/NACE MR0175 / ISO 15156-3; oilfield equipment is often additionally specified to API 6A CRA and an API 6A PSL level. ASME Boiler and Pressure Vessel Code Case 2218, Section VIII Division 1, covers pressure-retaining use. We certify to EN 10204 3.1, or 3.2 with third-party inspection.
What forged shapes can you make in Alloy 925?
Seamless rolled rings, flanges, shafts and spindles, round bars, discs and disks, sleeves and bushings, tube sheets, forged pipes and tubes, blocks, gear blanks, valve bodies, stems and seat rings, and near-net open-die blanks made to your drawing.
Can Alloy 925 be welded?
Yes. GTAW and GMAW are preferred, normally with an Alloy 725 type filler that outperforms matching 925 wire on both strength and corrosion resistance. Submerged arc and shielded metal arc welding are not recommended. Solution anneal before welding, and re-anneal plus age afterwards for the best weld toughness.
How is Alloy 925 machined?
Rough machine in the solution-annealed condition and finish after ageing, because the aged alloy runs up to about 40 HRC. Use rigid set-ups, positive rake angles, carbide for uninterrupted cuts, and slower surface speeds with heavier chip loads. Trepanned thin walls can move; a 621 °C / 2 h stress relief after trepanning reduces run-out.
What information do you need to quote?
A drawing or the finished dimensions, quantity, delivery condition, the governing specification, any NDT requirement, and the EN 10204 certification level. Email sales@steelforgepieces.com or call +86 189 2135 9659.
About Jiangyin Jiangnan Metal Co., Ltd.
Open-die forging factory · Jiangyin, Jiangsu, China
Jiangyin Jiangnan Metal Co., Ltd. is an open-die forging factory in Zhouzhuang Town, Jiangyin, Jiangsu Province, China, producing forged rings, seamless rolled rings, flanges, shafts, discs, sleeves and tube sheets in carbon steel, alloy steel, tool steel, stainless steel and nickel alloys including Alloy 925 (UNS N09925). Forgings are supplied to ASTM, ASME, EN, DIN and API specifications with EN 10204 3.1 or 3.2 certification, and shipped worldwide from Shanghai and Ningbo.
The works are in the Yangtze River Delta, about 150 km from Shanghai and close to Shanghai and Ningbo ports. Ingot supply, forging capacity and heat treatment furnaces are all available within the same industrial area, which keeps transfer times between operations short.
Company
Jiangyin Jiangnan Metal Co., Ltd.
Address
No.1 Chengxiqiao Road,
Zhouzhuang Town, Jiangyin City,
Jiangsu Province, China
Telephone
Website
Serving
Worldwide · English & Chinese
Title: Alloy 925 Forgings (UNS N09925): properties, heat treatment and manufacture
Issued by: Jiangyin Jiangnan Metal Co., Ltd., Jiangyin, Jiangsu, China
Source: https://www.steelforgepieces.com/Nickel-Alloy/ALLOY-925.html
Enquiries: sales@steelforgepieces.com · +86 189 2135 9659
Issued 18 May 2016 · Revised 14 August 2026
Trademark notice. INCOLOY, INCONEL, MONEL, NIMONIC and INCO-WELD are registered trademarks of the Special Metals Corporation group of companies. HASTELLOY is a registered trademark of Haynes International, Inc. Trade names are used on this page only to identify the corresponding UNS grade. Jiangyin Jiangnan Metal Co., Ltd. is not affiliated with, endorsed by, or a licensee of these companies, and supplies material to the applicable UNS, ASTM and API specifications.
Data notice. Property values are typical or specification-limit values compiled from published alloy literature and the governing standards, given for engineering guidance. They are not a warranty. The mill test certificate issued with each order, and the specification named on the purchase order, govern.
Published 18 May 2016 · Last reviewed 14 August 2026 by the technical sales team, Jiangyin Jiangnan Metal Co., Ltd.