Reviewed by the metallurgy team at Jiangyin Jiangnan Metal Co., Ltd. Last updated . Property data compiled from published Alloy 901 producer datasheets and our own works test results.
Alloy 901 at a glance
| Alloy designation | Alloy 901, Incoloy 901, Nimonic 901, Pyromet 901 |
|---|---|
| UNS number | N09901 |
| Werkstoff number | 2.4662 |
| Common specifications | AMS 5660, AMS 5661, BS HR 55, ISO 9723, ISO 9725, MSRR 7029, MSRR 7031 |
| Alloy family | Age-hardenable nickel-iron-chromium superalloy, γ′ strengthened |
| Nominal composition | 40 to 45 % Ni+Co, 11 to 14 % Cr, 5.0 to 6.5 % Mo, 2.8 to 3.1 % Ti, balance Fe |
| Density | 8.14 g/cm³ (0.294 lb/in³) |
| Melting range | 1280 to 1345 °C (2335 to 2455 °F) |
| Design temperature range | 540 to 760 °C (1000 to 1400 °F) |
| Forging temperature | 1010 to 1121 °C (1850 to 2050 °F) |
| Delivery condition | Solution treated, stabilised and aged. As forged or rough machined on request |
| Product forms forged | Seamless rolled rings, forged rings, discs, shafts, flanges, sleeves, bushings, tube sheets, blocks, round bars |
| Non-destructive testing | UT to EN 10228-3, SEP 1921 or ASTM A388. PT to ASTM E165. PMI |
| Certification | EN 10204 3.1 mill certificate. EN 10204 3.2 with SGS, BV, TÜV, DNV or LR |
| Minimum order quantity | 1 piece. Every forging is made to drawing |
| Typical lead time | 25 to 45 days from drawing approval |
| Manufactured by | Jiangyin Jiangnan Metal Co., Ltd., No.1 Chengxiqiao Road, Zhouzhuang Town, Jiangyin, Jiangsu, China |
What is Alloy 901?
Alloy 901 is a precipitation-hardening nickel-iron-chromium superalloy developed for parts that carry high stress at elevated temperature, principally gas turbine discs, rotors and shafts.
Two mechanisms give it strength. Titanium (2.80 to 3.10 %) and aluminium (up to 0.35 %) precipitate as γ′ Ni3(Al,Ti) during ageing. Molybdenum (5.00 to 6.50 %) strengthens the austenitic matrix in solid solution. Chromium at 11 to 14 % provides oxidation and corrosion resistance in gas turbine atmospheres, although scaling resistance sits slightly below that of Type 309 and 310 stainless steels.
The iron content is what separates Alloy 901 from fully nickel-based superalloys. Nickel plus cobalt is held at 40 to 45 % and iron makes up the balance, so the alloy costs less per kilogram and hot works more easily. It holds useful creep and yield strength to roughly 600 °C while still forging well. That is why it remains a standard disc and shaft material, and why it suits open-die forging as readily as closed-die or ring-rolled aerospace routes.
Naming note. Incoloy 901, Nimonic 901, Pyromet 901 and CarTech 901 are producer trade names for the same alloy. If your drawing calls out any of these, or UNS N09901, or Werkstoff 2.4662, we supply the same material. See also our pages for Incoloy 901 forgings and Nimonic 901 forgings.
Alloy 901 equivalents and specifications
| System | Designation | Covers |
|---|---|---|
| UNS (USA) | N09901 | Alloy identification |
| Werkstoff (Germany) | 2.4662 | Alloy identification |
| AMS | AMS 5660 | Bars, forgings and rings, solution treated |
| AMS | AMS 5661 | Bars, forgings and rings, heat treated |
| British | BS HR 55 | Bars and forgings |
| ISO | ISO 9723 / ISO 9725 | Bars / forgings |
| MSRR | MSRR 7029, MSRR 7031 | Rolls-Royce material specifications |
| AECMA | prEN 2176 / prEN 2177 | European aerospace bar and forging standards |
| Trade names | Incoloy 901, Nimonic 901, Pyromet 901, CarTech 901 | Producer designations for the same alloy |
Ordering to a specification. Alloy 901 forgings can be ordered to AMS 5661, to an OEM specification such as MSRR 7031, or to a purchase specification you supply. Give the exact specification and revision at RFQ stage. It sets the melting route, test frequency, grain size requirement and UT acceptance class, and therefore the price.
Chemical composition of Alloy 901
The limits below apply to Alloy 901 / UNS N09901. Every heat we forge is verified by ladle analysis and re-checked by product analysis. Both appear on the EN 10204 3.1 certificate.
| Element | Min % | Max % |
|---|---|---|
| Nickel + Cobalt (Ni+Co) | 40.0 | 45.0 |
| Chromium (Cr) | 11.0 | 14.0 |
| Molybdenum (Mo) | 5.00 | 6.50 |
| Titanium (Ti) | 2.80 | 3.10 |
| Aluminium (Al) | - | 0.35 |
| Cobalt (Co) | - | 1.00 |
| Carbon (C) | - | 0.10 |
| Manganese (Mn) | - | 0.50 |
| Silicon (Si) | - | 0.40 |
| Copper (Cu) | - | 0.50 |
| Sulfur (S) | - | 0.03 |
| Iron (Fe) | Remainder (balance) | |
Melting route
Billet is normally double melted as EAF + VOD + ESR (electric arc furnace, vacuum oxygen decarburisation, electroslag remelting). This route gives the low sulfur and the clean, dense structure a γ′-hardened alloy needs. Where an aerospace specification calls for it, VIM + VAR (vacuum induction melting plus vacuum arc remelting) billet can be supplied instead. State the melting route on your enquiry, as it affects both price and lead time.
Mechanical properties of Alloy 901
Minimum room-temperature properties, aged condition
| Condition | Tensile strength Rm | 0.2 % proof Rp0.2 | Elongation A5 |
|---|---|---|---|
| Alloy 901, solution treated + aged | ≥ 1034 N/mm² (150 ksi) | ≥ 689 N/mm² (100 ksi) | ≥ 12 % |
Typical tensile properties versus temperature
The values below are typical for material solution treated at 1093 °C for 2 h and water quenched, stabilised at 774 °C for 4 h and air cooled, then aged at 732 °C for 24 h and air cooled. They are given for guidance, not as guaranteed minima. The guaranteed figures for your order are the ones on the certificate.
| Temp °C | Temp °F | 0.2 % yield MPa | Tensile MPa | Elong. % | R of A % |
|---|---|---|---|---|---|
| 21 | 70 | 862 | 1207 | 15.0 | 19.0 |
| 427 | 800 | 803 | 1096 | 16.0 | 25.5 |
| 538 | 1000 | 779 | 1076 | 17.0 | 29.0 |
| 649 | 1200 | 807 | 1034 | 14.0 | 21.0 |
| 704 | 1300 | 786 | 896 | 11.5 | 15.5 |
| 760 | 1400 | 707 | 741 | 9.0 | 14.5 |
| 816 | 1500 | 545 | 559 | 13.0 | 20.0 |
Typical stress-rupture strength
| Temp °C | Temp °F | 10 h | 100 h | 1000 h |
|---|---|---|---|---|
| 538 | 1000 | - | 827 | 689 |
| 649 | 1200 | 665 | 621 | 517 |
| 732 | 1350 | 414 | 352 | 228 |
| 816 | 1500 | 241 | 155 | 76 |
Physical properties of Alloy 901
| Density | 8.14 g/cm³ (0.294 lb/in³) |
|---|---|
| Melting range | 1280 to 1345 °C (2335 to 2455 °F) |
| Specific heat | 431 J/kg·°C (0.103 Btu/lb·°F) |
| Coefficient of thermal expansion, 20 to 100 °C | 13.5 µm/m·°C (7.50 ×10⁻⁶ in/in·°F, 68 to 212 °F) |
| Electrical resistivity | 1.12 µΩ·m (674 Ω·cir mil/ft) |
| Magnetic permeability at 200 oersted (15.9 kA/m) | 1.013 |
For weight estimating: an Alloy 901 ring of OD 600 mm × ID 400 mm × H 200 mm has a volume of about 31.4 dm³, so it weighs roughly 256 kg at 8.14 g/cm³ before machining allowance. Send the finished drawing and we will calculate the forged weight including allowance.
Heat treatment of Alloy 901 forgings
Alloy 901 develops its properties through a three-stage cycle. We carry out all three stages in-house on calibrated, chart-recorded furnaces, and the charts are issued with the certificate.
| Stage | Temperature | Hold | Cooling | Purpose |
|---|---|---|---|---|
| Solution treatment | 1080 to 1107 °C (1975 to 2025 °F) |
2 h | Water quench | Dissolve γ′ and carbides, set grain size |
| Stabilisation | 760 to 802 °C (1400 to 1475 °F) |
2 to 4 h | Air cool | Precipitate grain-boundary carbides, improve rupture ductility |
| Precipitation hardening (ageing) | 704 to 746 °C (1300 to 1375 °F) |
24 h | Air cool | Precipitate fine γ′ Ni3(Al,Ti), develops final strength |
Welding Alloy 901
Alloy 901 can be joined by inert-gas arc processes such as GTAW, but as a γ′-hardened alloy it is regarded as difficult to weld and is susceptible to strain-age cracking. Weld in the solution treated condition. Cold-worked parts should be re-solution treated before welding, and a re-solution treatment after welding is recommended before stabilising and ageing. Where the design allows, a one-piece forging is usually preferable to a welded fabrication.
How we forge Alloy 901
Alloy 901 has a narrow hot-working window and work-hardens quickly, so forging practice matters more than it does for carbon or alloy steel. Our route:
- Billet preparation and charging Billets are charged into a hot furnace and heated rapidly through the precipitation-hardening range, so the alloy does not sit at temperatures where γ′ forms and ductility drops.
- Forging window 1121 to 1010 °C The alloy is forged between 2050 °F and 1850 °F metal temperature. Light hot work may continue down to 871 °C (1600 °F) but no lower. Metal temperature must not exceed 1121 °C during rapid working, or incipient melting and cracking follow.
- Upsetting and drawing, or ring rolling Rings are upset, punched and then saddle forged or rolled. Discs are upset and flattened. Shafts are drawn down with controlled bites. We target a reduction ratio of at least 3:1 from billet so the wrought structure runs continuously through the section.
- Reheats Reduction is spread over several controlled reheats rather than forced into one heat. Dynamic recrystallisation is only complete above roughly 1100 °C, and working the alloy too cold is where Alloy 901 cracks.
- Grain-flow control The forging sequence is planned so grain flow follows the contour of the finished part: around the bore on a disc, along the axis on a shaft. This is the reason a rotating part is forged rather than cut from plate or bar.
- Heat treatment Solution treat, stabilise and age as tabulated above, with chart recording and calibrated thermocouples.
- Rough machining and NDT Parts are rough machined to a geometry suited to ultrasonic inspection, then UT tested and, where specified, penetrant tested and PMI checked.
Capability note. Alloy 901 forgings are produced at our works in Zhouzhuang Town, Jiangyin, Jiangsu Province. Single-piece weight range and press capacity vary by shape. Send your drawing and we will confirm whether the part suits an open-die, saddle-forged or rolled-ring route before quoting.
Alloy 901 forging forms and size range
| Form | Dimensions quoted as | Common end use |
|---|---|---|
| Seamless rolled rings | OD × ID × H | Turbine casings, spacers, retaining rings |
| Forged rings and sleeves | OD × ID × H | Bushings, sleeves, wear rings |
| Discs and disc blanks | OD × thickness | Turbine and compressor discs, hubs |
| Shafts and stepped shafts | OD × length per step | Rotor shafts, spindles, pump shafts |
| Flanges | OD × ID × thickness | High-temperature piping and vessel connections |
| Tube sheets and blocks | L × W × T, or OD × T | Heat exchangers, valve bodies, manifolds |
| Round bars and hollow bars | OD × length, or OD × ID × length | Machining stock, bolting, valve stems |
- As forged
- Rough machined
- Finish machined to drawing
- Solution treated
- Stabilised
- Aged
- Machining allowance to agreement
Testing, inspection and certification
Every Alloy 901 forging is tested to an inspection and test plan agreed before production starts.
| Test | Standard | Notes |
|---|---|---|
| Chemical analysis | Ladle and product analysis | Reported against UNS N09901 limits |
| Tensile test | ASTM E8 / ISO 6892-1 | Room temperature. Elevated temperature on request |
| Hardness | ASTM E10 / ASTM E18 | Brinell or Rockwell |
| Grain size | ASTM E112 | Where the specification requires it |
| Ultrasonic testing | EN 10228-3, SEP 1921, ASTM A388 | Acceptance class to agreement, for example SEP 1921 Class D/d |
| Liquid penetrant | ASTM E165 / EN ISO 3452 | On machined surfaces where specified |
| Positive material identification | PMI by XRF or OES | Confirms grade on the finished part |
| Certificate | EN 10204 3.1 | Standard on every order |
| Third-party certificate | EN 10204 3.2 | SGS, BV, TÜV, DNV, Lloyd's Register on request |
Where Alloy 901 forgings are used
Alloy 901 is chosen where a part must hold high stress at temperature without the cost of a fully nickel-based superalloy. Typical applications for our forgings:
- Gas turbines and aero-engines. Turbine discs, compressor discs, rotor hubs, spacers, shafts, ring components and high-temperature bolting.
- Power generation. Turbine and gas compressor shafts, spindles, gearbox and power-transmission forgings.
- Oil and gas. Subsea and deepwater production components, wellhead and Christmas-tree parts, forged valve bodies, seat rings, stems and blocks for ball, gate, globe, check and plug valves.
- Chemical and process plant. Pump shafts for chemical and plunger pumps, forged nozzles, crystalliser parts, column and tower internals, process module components.
- Pressure vessels and heat exchangers. Tube sheets, flanges, forged shells and shafts for shell-and-tube exchangers, air receivers and preheaters.
- Heavy machinery. Forged rolls, wheels, manifolds, eccentric and crank shafts for mills, mixers, marine and paper and pulp equipment.
Alloy 901 compared with other disc alloys
The question that comes up most often is Alloy 901 or Inconel 718. Rough guidance:
| Alloy | UNS | Base and strengthening | Typical upper useful temp. | Chosen when |
|---|---|---|---|---|
| Alloy 901 | N09901 | Ni-Fe-Cr, γ′ Ni3(Al,Ti) plus Mo | about 600 °C | Good creep strength and forgeability at moderate nickel content and cost |
| Inconel 718 | N07718 | Ni-Cr-Fe, γ″ (Nb) plus γ′ | about 650 °C | Weldability matters, or the most widely qualified disc alloy is required |
| Waspaloy | N07001 | Ni-Cr-Co, γ′ | about 760 °C | Temperature exceeds what 718 or 901 can hold, and cost is secondary |
| A-286 | S66286 | Fe-Ni-Cr, γ′ | about 700 °C | Lowest cost of the age-hardened group, with lower strength accepted |
| Inconel X-750 | N07750 | Ni-Cr, γ′ | about 700 °C | Springs, fasteners and lower-stress high-temperature parts |
Upper temperature figures are practical limits for stressed rotating parts, not code allowables. The controlling factor is the combination of stress, required life and design code. Confirm any choice with your own design authority.
How to order Alloy 901 forgings
Send the items below to sales@steelforgepieces.com and we normally return a quotation within 24 hours.
- Drawing or dimensions A PDF, DWG or STEP drawing is best. Without a drawing, give OD × ID × H for a ring, OD × thickness for a disc, or OD × length for a shaft.
- Specification and revision For example AMS 5661, MSRR 7031, or your own purchase specification.
- Delivery condition As forged, rough machined or finish machined, and the machining allowance you want.
- Heat treatment condition Solution treated, or solution treated plus stabilised plus aged.
- NDT requirement UT standard and acceptance class, plus PT or MT if required.
- Certificate type EN 10204 3.1, or 3.2 with a named third party.
- Quantity and destination port For freight and packing.
The quotation covers forged weight, unit price, lead time and the proposed manufacturing route. Minimum order quantity is one piece. Typical lead time is 25 to 45 days from drawing approval.
Alloy 901 frequently asked questions
- What is Alloy 901?
- Alloy 901 is an age-hardenable nickel-iron-chromium superalloy, designated UNS N09901 and Werkstoff 2.4662. It contains 40 to 45 % nickel plus cobalt, 11 to 14 % chromium, 5.0 to 6.5 % molybdenum and 2.8 to 3.1 % titanium, with iron as the balance. Titanium and aluminium form γ′ Ni3(Al,Ti) precipitates that provide strength, while molybdenum strengthens the matrix in solid solution. Its high iron content makes it cheaper and easier to forge than fully nickel-based superalloys.
- Is Alloy 901 the same as Incoloy 901 and Nimonic 901?
- Yes. Incoloy 901 and Nimonic 901 are trade names for the same alloy composition, designated UNS N09901 and Werkstoff 2.4662. Pyromet 901 and CarTech 901 are further producer names for it. We supply forgings against any of these designations to the same chemistry and specification.
- What is the maximum service temperature of Alloy 901?
- Alloy 901 was designed for high strength and corrosion resistance in the 538 to 760 °C (1000 to 1400 °F) range. In practice its useful yield and creep strength is normally exploited up to about 600 °C (1110 °F). Above roughly 700 °C its strength falls away faster than that of Waspaloy or Inconel 718. The real limit depends on stress, required life and the design code applied.
- What heat treatment is used for Alloy 901 forgings?
- The standard three-stage cycle is solution treatment at 1080 to 1107 °C for 2 hours with water quench, stabilisation at 760 to 802 °C for 2 to 4 hours with air cool, then precipitation hardening at 704 to 746 °C for 24 hours with air cool. All three stages are carried out in-house and the furnace charts are issued with the certificate.
- Can Alloy 901 be welded?
- It can be welded by inert-gas arc methods such as GTAW, but it is considered difficult to weld because it is a γ′-hardened alloy prone to strain-age cracking. Weld in the solution treated condition. Re-solution treat cold-worked parts before welding, and re-solution treat after welding before stabilising and ageing.
- What is the density of Alloy 901?
- The density of Alloy 901 (UNS N09901) is 8.14 g/cm³, equal to 0.294 lb/in³. Its melting range is 1280 to 1345 °C (2335 to 2455 °F).
- How does Alloy 901 compare with Inconel 718?
- Both are age-hardenable disc alloys strengthened by different mechanisms. Alloy 901 is nickel-iron-chromium, strengthened by γ′ Ni3(Al,Ti) plus molybdenum, at 40 to 45 % Ni+Co. Inconel 718 is nickel-chromium at roughly 50 to 55 % nickel, strengthened mainly by niobium-bearing γ″. Inconel 718 welds far more readily and is usually preferred up to about 650 °C. Alloy 901 offers good creep strength and forgeability at lower nickel content and cost.
- What forms of Alloy 901 forgings can be supplied?
- Seamless rolled rings, forged rings, discs and disc blanks, shafts and stepped shafts, spindles, flanges, sleeves, bushings, hollow bars, tube sheets, blocks and round bars, all open-die forged to customer drawing with machining allowance. Turbine disc and shaft blanks are the most common Alloy 901 items.
- What certificates are supplied with Alloy 901 forgings?
- Every forging carries an EN 10204 3.1 mill certificate showing heat number, chemical analysis, mechanical test results, heat treatment records and NDT results. An EN 10204 3.2 certificate witnessed by SGS, BV, TÜV, DNV or Lloyd's Register can be arranged on request.
- What is the minimum order quantity and lead time for Alloy 901 forgings?
- Minimum order quantity is one piece, since every forging is made to the customer's drawing. Typical lead time is 25 to 45 days from drawing approval, depending on size, melting route and whether third-party witnessed inspection is required.
- What information is needed to quote an Alloy 901 forging?
- A drawing or the rough dimensions, the specification and revision, the delivery condition, the heat treatment condition, the NDT acceptance class, the certificate type and the quantity. Send it to sales@steelforgepieces.com and a quotation normally follows within 24 hours.
- Where is Alloy 901 used?
- Gas turbine and aero-engine discs, turbine rotors, compressor discs and hubs, shafts, spacers, casings, ring components and high-temperature bolting. Also oil and gas equipment, chemical process pumps, pressure vessel internals and power transmission parts seeing combined high stress and temperatures up to about 600 °C.
Data sources and use of this data
Property values on this page are compiled from published Alloy 901 producer datasheets and from our own works test results. They are given for engineering guidance. The binding values for any order are those stated on the EN 10204 certificate issued with the forging.
If you quote figures from this page in a specification, report or enquiry, please reference it as:
Jiangyin Jiangnan Metal Co., Ltd. (2026). "Alloy 901 Forgings (UNS N09901): Technical Datasheet."
Jiangyin, Jiangsu, China.
https://www.steelforgepieces.com/Nickel-Alloy/ALLOY-901.html
Related nickel alloy forgings
We forge the full range of nickel-based superalloys to drawing. Grades frequently specified alongside Alloy 901:
- Incoloy 901 forgings and Nimonic 901 forgings, the same alloy under producer trade names
- Inconel 706 and Inconel X-750, age-hardenable disc and fastener alloys
- Waspaloy, Udimet 720 and Rene 41, higher-temperature γ′ alloys
- Nimonic 80A, Nimonic 90, Nimonic 105 and Nimonic 263, Nimonic series forgings
- Incoloy 925, Incoloy 825 and Incoloy 800H, corrosion-resistant Ni-Fe-Cr alloys
- Hastelloy C-276, Hastelloy C-22 and Monel K-500, corrosion service forgings
Browse all nickel alloy forgings, or see our stainless steel, alloy steel, tool steel and carbon steel forging ranges.