Nickel superalloy · UNS N09901 · W.Nr. 2.4662
Nimonic 901 Forgings: Rings, Discs, Flanges, Shafts and Bars
Material identification
Reviewed 25 Aug 2026
Nimonic 901 (UNS N09901, W.Nr. 2.4662, also sold as Incoloy 901 or Alloy 901) is a precipitation-hardenable nickel–iron–chromium superalloy strengthened by molybdenum, titanium and aluminium. It holds high tensile and creep-rupture strength to about 600 °C (1,110 °F), which makes it a standard disc-and-shaft alloy for gas turbines. Jiangyin Jiangnan Metal Co., Ltd. forges it to AMS 5660 at its open-die plant in Jiangyin, Jiangsu, China, as seamless rolled rings, discs, flanges, shafts, sleeves, bars and blocks, with EN 10204 3.1 or 3.2 certification.
- Grade
- Nimonic 901
- Also known as
- Incoloy 901 · Alloy 901 · Pyromet 901 · CarTech 901
- UNS
- N09901
- Werkstoff
- 2.4662
- Specifications
- AMS 5660 · AMS 5661 · BR HR 55 · MSRR 7029 / 7031 · ISO 9723 / 9725
- Alloy system
- Ni–Fe–Cr, γ′ precipitation-hardened
- Nominal chemistry
- Ni 42.5 · Cr 12.5 · Mo 5.75 · Ti 2.9 · Fe bal.
- Service limit
- ~600 °C (1,110 °F) for stressed rotating parts
- Melt route
- EAF + VOD + ESR; VIM + VAR on request
- Supply condition
- Solution treated, or solution treated + aged
- Product forms
- Rolled rings, discs, flanges, shafts, sleeves, bars, blocks, tube sheets
- Certification
- EN 10204 3.1 / 3.2, third-party witness on request
- Manufacturer
- Jiangyin Jiangnan Metal Co., Ltd.
- Plant
- No.1 Chengxiqiao Road, Zhouzhuang Town, Jiangyin City, Jiangsu, China
01What Nimonic 901 is
Nimonic 901 is specified where a rotating part has to stay dimensionally stable and creep-resistant at 550–600 °C without the cost of a cobalt-rich superalloy.
Its strength comes from γ′, the ordered Ni3(Ti, Al) precipitate that forms during aging. Molybdenum at around 5.75 % does the solid-solution work in the matrix, chromium at 12.5 % supplies oxidation and hot-corrosion resistance in combustion atmospheres, and roughly a third of the alloy is iron. That dilution is deliberate. It makes 901 considerably cheaper per kilogram than Waspaloy or René 41 while retaining most of the useful strength below 600 °C.
The high titanium-to-aluminium ratio is the alloy's defining feature and its main processing constraint. That ratio makes 901 prone to forming η phase (Ni3Ti) in a Widmanstätten morphology. Left uncontrolled it embrittles the part. Used deliberately, normally as an 8 h hold near 900 °C early in the sequence, it pins grain boundaries during thermomechanical processing and produces the fine, uniform grain that gives 901 its fatigue life. Controlling it is a forging-shop problem rather than a chemistry problem, which is why 901 forgings are best bought from a shop that runs the grade regularly.
Because titanium and aluminium age-harden during cooling from welding temperature, Nimonic 901 is difficult to fusion weld and is prone to strain-age cracking. Designs are normally all-forged or mechanically fastened rather than fabricated.
02Equivalent designations and specifications
Nimonic 901, Incoloy 901 and Alloy 901 are the same material under different mill trade names. A drawing that calls out any of the designations below is satisfied by the same certified heat.
| System | Designation | Scope / note |
|---|---|---|
| UNS | N09901 | Unified Numbering System, USA |
| Werkstoff | 2.4662 | German material number |
| SAE / AMS | AMS 5660 | Bars, forgings and rings, solution treated |
| SAE / AMS | AMS 5661 | Bars, forgings and rings, solution treated and precipitation hardened |
| British | BR HR 55 | Bar and forging stock |
| Rolls-Royce | MSRR 7029 / MSRR 7031 | Engine-builder material standards |
| ISO | ISO 9723 / ISO 9725 | Wrought bar / forgings |
| AECMA | prEN 2176 / prEN 2177 | European aerospace bar and forging |
| Trade names | Nimonic 901, Incoloy 901, Alloy 901, Pyromet 901, CarTech 901 | Same alloy, different producers |
Nimonic® and Incoloy® are registered trade marks of their respective owners and are used here only to identify the alloy grade.
03Chemical composition
Limits below follow AMS 5660. Every heat we forge is supplied with a full certified analysis, and we run PMI on the billet before it goes into the furnace.
| Element | Min | Max | Typical |
|---|---|---|---|
| Nickel (Ni) | 40.0 | 45.0 | 42.5 |
| Chromium (Cr) | 11.0 | 14.0 | 12.5 |
| Molybdenum (Mo) | 5.0 | 6.5 | 5.75 |
| Titanium (Ti) | 2.35 | 3.10 | 2.90 |
| Boron (B) | 0.010 | 0.020 | 0.015 |
| Aluminium (Al) | – | 0.35 | 0.25 |
| Carbon (C) | – | 0.10 | 0.05 |
| Cobalt (Co) | – | 1.00 | – |
| Copper (Cu) | – | 0.50 | – |
| Manganese (Mn) | – | 0.50 | – |
| Silicon (Si) | – | 0.40 | – |
| Sulphur (S) | – | 0.030 | – |
| Phosphorus (P) | – | 0.015 | – |
| Iron (Fe) | Balance | ~34–36 | |
Aerospace orders to AMS 5660 also carry trace-element limits (Pb, Bi, Se). State the specification on the purchase order and the melt will be controlled to it.
04Mechanical properties
Room-temperature minimums in the solution-treated and aged condition, tested to ASTM E8/E8M on a coupon cut from the forging.
| Property | Metric | Imperial |
|---|---|---|
| Tensile strength | 1,035 MPa min | 150 ksi min |
| Yield strength, 0.2 % offset | 690 MPa min | 100 ksi min |
| Elongation in 4D | 12 % min | 12 % min |
| Reduction of area | 15 % min | 15 % min |
| Hardness, aged | ~331 HB | ~36 HRC |
Elevated-temperature tensile and stress-rupture testing is available per heat on request, including test temperature, stress and hold time nominated on your purchase order. Rupture testing follows ASTM E139 and the results are reported on the certificate against the acceptance criteria you specify.
05Physical properties
| Property | Value |
|---|---|
| Density | 8.19 g/cm³ (0.296 lb/in³) |
| Melting range | approx. 1,280–1,345 °C (2,336–2,453 °F) |
| Modulus of elasticity, 20 °C | approx. 200 GPa (29 × 10&sup6; psi) |
| Typical service ceiling, stressed parts | 600 °C (1,110 °F) |
| Magnetic response | Essentially non-magnetic; use PT rather than MT for surface NDT |
| Machinability index | approx. 13 % of free-cutting steel |
| Weldability | Poor; susceptible to strain-age cracking |
Typical published values for guidance and comparison. They are not design allowables. Design to the values in the specification your part is bought to.
06Heat treatment
Nimonic 901 needs a three-stage cycle. The stabilising step between solution and aging is what develops controlled grain-boundary η phase; skipping it costs rupture ductility.
1,994 °F · hold 3 h · water quench
1,427 °F · hold 4 h · air cool
1,301–1,328 °F · hold 24 h · air cool
Furnaces are surveyed and instrumented to AMS 2750 pyrometry requirements and the time–temperature chart for your heat is issued with the certificate. Where a fine-grain thermomechanical route is specified, an additional hold near 900 °C for 8 h is used early in the sequence to introduce η phase in Widmanstätten form before final forging.
07How we forge Nimonic 901
Each step is signed off on the traveller card before the part moves to the next one.
-
Melt and billet
EAF + VOD followed by ESR remelt for cleanliness and segregation control; VIM + VAR where the specification demands it. Ingot chemistry certificate travels with the billet, and PMI is run before charging.
-
Heating
Billet charged below 800 °C and soaked at 1,050–1,130 °C with through-thickness temperature verified. Nimonic 901 has a narrow hot-working window and an overheated billet is scrap, so the soak is timed to section thickness.
-
Open-die forging or ring rolling
Pressed on hydraulic open-die presses, or ring-rolled on radial–axial mills for seamless rings. Total reduction ratio is logged per piece and finish-forging temperature is held above 950 °C to avoid cracking.
-
Heat treatment
The three-stage cycle in section 06, in AMS 2750 surveyed furnaces, with charts retained against the heat number.
-
Rough machining
Turned or bored to sonic shape so the ultrasonic inspection sees the material the finished part will actually be made from. We can also supply finish-machined to your drawing.
-
Non-destructive testing
Ultrasonic testing to EN 10228-3, SEP 1921 or ASTM A388 to the acceptance class you nominate. Surface inspection by liquid penetrant to ASTM E165. Because 901 is non-magnetic, magnetic particle testing does not apply.
-
Certification and release
EN 10204 3.1 as standard, or 3.2 with witness by TUV, BV, SGS or Lloyd's Register. Certificate carries chemistry, mechanicals, heat-treatment charts, NDT reports and full heat traceability.
08Product forms and size range
| Form | Size range | Typical use |
|---|---|---|
| Seamless rolled rings | OD 200–3,000 mm | Turbine casings, seal rings, bearing races |
| Forged rings | OD 100–1,500 mm | Spacers, retaining rings |
| Discs and blanks | Ø 100–1,500 mm | Turbine discs, compressor wheels |
| Shafts and spindles | Ø 50–600 mm, L to 6,000 mm | Rotor shafts, eccentric shafts, spindles |
| Round bar | Ø 20–600 mm | Fasteners, bolting, machined parts |
| Flanges | DN15–DN1200, Class 150–2500 | Pressure-boundary connections |
| Sleeves and bushings | OD to 1,200 mm | Wear surfaces, liners |
| Blocks and step blocks | To 800 mm thick | Valve bodies, dies, machined housings |
| Tube sheets | Ø to 2,500 mm | Heat exchangers, preheaters |
| Hollow forgings and pipe | OD to 1,200 mm | Cylinders, bored sections |
Non-standard geometry is normal work for an open-die shop. If the part is close to one of these envelopes, send the drawing. The constraint is usually billet weight rather than shape.
09Where Nimonic 901 forgings are used
Gas turbines
Discs, shafts, seal rings, casings, spacers and compressor components running to about 600 °C. This is the alloy's original and largest application.
Oil, gas and subsea
Valve bodies, stems, seat rings, blocks, wellhead and Christmas-tree components, hangers and subsea production hardware.
Power generation
Turbine rotors, gas-compressor parts, gearbox components, generator and nitrogen-generator hardware.
Petrochemical and process
Tube sheets, nozzles, forged flanges and shell sections for columns, towers, preheaters, shell-and-tube exchangers and process modules.
Nuclear
Boiler tube supports and structural forgings where low-cobalt chemistry and thermal stability are specified.
Automotive and motorsport
Exhaust valves, turbocharger components and high-temperature fasteners in racing and heavy-duty engines.
Also used in high-temperature bolting, die-casting inserts and cores, paper and pulp machinery, pharmaceutical and biochemical process equipment, marine and heavy machinery.
10Nimonic 901 compared with other superalloys
901 is a mature disc alloy. If your drawing calls for it, buy it. For a new design, Inconel 718 is usually easier to procure and fabricate.
| Alloy | UNS | Base | Strengthened by | Typical ceiling | When it is the better pick |
|---|---|---|---|---|---|
| Nimonic 901 | N09901 | Ni–Fe–Cr | γ′ Ni3(Ti,Al) | ~600 °C | Existing engine drawings, repair and overhaul, stable 550–600 °C discs at moderate cost |
| Inconel 718 | N07718 | Ni–Fe–Cr | γ″ Nb-bearing | ~650 °C | New designs, anything that must be welded, best availability worldwide |
| Waspaloy | N07001 | Ni–Co–Cr | γ′ | ~760 °C | Hotter discs and shafts where 901 runs out of strength; higher cost |
| Incoloy 901 | N09901 | Ni–Fe–Cr | γ′ | ~600 °C | Identical alloy under a different trade name |
| Nimonic 80A | N07080 | Ni–Cr | γ′ | ~815 °C | Exhaust valves and low-cobalt nuclear parts rather than loaded discs |
| Inconel 706 | N09706 | Ni–Fe–Cr | γ″ + γ′ | ~650 °C | Very large land-based turbine discs needing better machinability than 718 |
11How to order Nimonic 901 forgings
Send whatever you have. A drawing is ideal; a size list is enough. A quotation normally comes back within one working day.
- Geometry: drawing (STEP, DWG or PDF), or finished dimensions plus the machining allowance you want left on.
- Quantity and whether this is a one-off, a prototype or a repeat order.
- Specification: AMS 5660, AMS 5661, MSRR or a customer standard.
- Delivery condition: as forged, solution treated, or solution treated and aged.
- Testing: UT class and standard, PT, elevated-temperature tensile, stress rupture, grain size.
- Certification: EN 10204 3.1, or 3.2 and which inspection body.
- Destination port, so freight and packing can be quoted with the piece price.
Get a quotation for your Nimonic 901 part
Your enquiry goes straight to the plant that will make the part.
12Frequently asked questions
What is Nimonic 901?
Nimonic 901 is a precipitation-hardenable nickel–iron–chromium superalloy designated UNS N09901 and W.Nr. 2.4662. Molybdenum provides solid-solution strengthening while titanium and aluminium form the gamma-prime Ni3(Ti, Al) precipitate that carries its strength. It keeps high tensile and creep-rupture properties to about 600 °C, which is why it is used for gas-turbine discs, shafts, rings, casings and seals.
Is Nimonic 901 the same as Incoloy 901 and Alloy 901?
Yes. Nimonic 901, Incoloy 901, Alloy 901, Pyromet 901 and CarTech 901 are trade names for the same alloy, UNS N09901 / W.Nr. 2.4662, covered by AMS 5660 and AMS 5661. Jiangyin Jiangnan Metal Co., Ltd. supplies forgings under any of these designations against the same specification.
What is the UNS number for Nimonic 901?
The UNS number for Nimonic 901 is N09901. The corresponding German Werkstoff number is 2.4662 and the British designation is BR HR 55. Aerospace procurement is normally to AMS 5660 for bars, forgings and rings, or AMS 5661 for the aged condition.
What is the maximum service temperature of Nimonic 901?
Rotating and highly stressed Nimonic 901 parts such as turbine discs are normally limited to about 600 °C (1,110 °F). The alloy retains useful strength and oxidation resistance at higher temperatures in lightly loaded service, but above roughly 650 °C designers usually move to Waspaloy or Inconel 718.
What heat treatment is used for Nimonic 901 forgings?
The standard cycle has three stages: solution treat 3 hours at 1090 °C and water quench, stabilise 4 hours at 775 °C and air cool, then age 24 hours at 705–720 °C and air cool. Jiangyin Jiangnan Metal Co., Ltd. runs this cycle in furnaces surveyed to AMS 2750 pyrometry and issues the chart with the certificate.
Nimonic 901 or Inconel 718: which should I specify?
Inconel 718 is strengthened by niobium-bearing gamma double prime, welds far more easily and is the default for new designs to about 650 °C. Nimonic 901 is a gamma-prime disc alloy with better long-term thermal stability in the 550–600 °C band and is normally specified when an existing drawing, engine build standard or repair scheme calls for it.
Who manufactures Nimonic 901 forgings in China?
Jiangyin Jiangnan Metal Co., Ltd. is an open-die forging factory at No.1 Chengxiqiao Road, Zhouzhuang Town, Jiangyin City, Jiangsu Province, China that produces Nimonic 901 (UNS N09901) forged rings, seamless rolled rings, discs, flanges, shafts, sleeves and bars to AMS 5660 with EN 10204 3.1 or 3.2 certification. Contact +86-189-2135-9659 or sales@steelforgepieces.com.
What testing and certification are supplied with Nimonic 901 forgings?
Every heat is supplied with chemical analysis, room-temperature tensile results and hardness. Ultrasonic testing is performed to EN 10228-3, SEP 1921 or ASTM A388 and liquid penetrant to ASTM E165. Certification is issued to EN 10204 3.1, or 3.2 with witness by TUV, BV, SGS or Lloyd's Register when required.
What is the minimum order quantity for Nimonic 901 forgings?
Single pieces are accepted. Because Nimonic 901 is ordered as billet by weight, small orders are usually most economical when several parts are nested into one billet or when a size close to a standard billet diameter is chosen. Send the drawing and the quantity and a nesting proposal will be quoted with the price.
Is Nimonic 901 difficult to machine?
Yes. Nimonic 901 has a machinability rating near 13 percent of free-cutting steel and work-hardens quickly, so rigid setups, sharp positive geometry, heavy constant feed and generous coolant are all needed. Rough machining in the solution-treated condition and finishing after aging gives the best result, and forgings can be supplied rough-machined to sonic shape.
About the manufacturer
Jiangyin Jiangnan Metal Co., Ltd. is an open-die forging factory in Jiangyin, Jiangsu Province, in the ring and forging cluster on the south bank of the Yangtze, about two hours from Shanghai port. We forge carbon steel, alloy steel, tool steel, stainless steel and nickel-base superalloys into rings, seamless rolled rings, flanges, discs, shafts, sleeves, bars and blocks, from single prototype pieces to production runs, and ship worldwide under EN 10204 3.1 or 3.2 certification.
- Company
- Jiangyin Jiangnan Metal Co., Ltd.
- Type
- Open-die forging factory (manufacturer, not trader)
- Address
- No.1 Chengxiqiao Road, Zhouzhuang Town, Jiangyin City, Jiangsu Province, China
- Telephone
- +86 189 2135 9659
- Website
- www.steelforgepieces.com
- Materials
- Nickel superalloys, stainless, tool, alloy and carbon steel
- Markets served
- Worldwide
Cite or reuse this datasheet
The data on this page may be reproduced with attribution.
Suggested citation: Jiangyin Jiangnan Metal Co., Ltd. (2026). Nimonic 901 forgings (UNS N09901 / Alloy 901). Technical datasheet. Jiangyin, Jiangsu, China. https://www.steelforgepieces.com/Nickel-Alloy/Nimonic-901.html
Source of the manufacturing data: Jiangyin Jiangnan Metal Co., Ltd., open-die forging factory, No.1 Chengxiqiao Road, Zhouzhuang Town, Jiangyin City, Jiangsu Province, China. Telephone +86-189-2135-9659, email sales@steelforgepieces.com.
Last reviewed: . Chemical and mechanical limits follow AMS 5660; manufacturing, testing and certification details describe this factory's own practice.