Nickel-base superalloy forgings
Incoloy 901 Forgings UNS N09901 · W.Nr. 2.4662 · AMS 5660 / AMS 5661 · Alloy 901 · Nimonic 901
Jiangyin Jiangnan Metal Co., Ltd. forges Incoloy 901 to customer drawing: seamless rolled rings, discs, shafts, flanges, sleeves, bushings, tube sheets and round bars, 5 kg to 8,000 kg per piece. Solution treatment and ageing are carried out in house. Parts are ultrasonically tested and certified to EN 10204 3.1 or 3.2.
Overview
Incoloy 901 (UNS N09901, W.Nr. 2.4662, also sold as Alloy 901 and Nimonic 901) is an age-hardenable nickel-iron-chromium superalloy containing about 42.5% nickel, 12.5% chromium, 5.75% molybdenum and 2.9% titanium, with the balance iron. Titanium and aluminium precipitate as gamma-prime Ni3(Al,Ti), which provides the strength. Molybdenum strengthens the solid solution. The high iron content makes the alloy easier to forge than most nickel-base superalloys, so it is widely used for gas-turbine discs, shafts, rings, casings and seals operating to about 600 °C (1,110 °F). Bar and forgings are ordered to SAE AMS 5660 or AMS 5661. ASTM B564 does not list UNS N09901.
Material identification
- UNS
- N09901
- Werkstoff
- 2.4662
- SAE AMS
- 5660 / 5661
- British
- BS HR 55
- ISO
- 9723 / 9725
- Density
- 8.14 g/cm³
- Melting range
- 1280–1345 °C
- Max service
- 600 °C
- UTS (aged, RT)
- 1207 MPa
- 0.2% YS (aged, RT)
- 862 MPa
- Forge range
- 1010–1120 °C
- Magnetic
- No, µ 1.013
Values on this page are typical published data for wrought Alloy 901 in the solution-treated, stabilised and aged condition. They are given for material selection, not for design. Order-specific properties are recorded on the mill certificate issued with each shipment.
What is Incoloy 901?
Incoloy 901 is a precipitation-hardening superalloy built on an iron-nickel-chromium base rather than a purely nickel base. The roughly 36% iron content lowers the cost per kilogram against alloys such as Waspaloy, and it widens the hot-working window so that large sections can be open-die forged and ring rolled without the cracking risk of high gamma-prime grades.
The alloy was developed for rotating gas-turbine hardware. Between 538 °C and 732 °C (1,000 to 1,350 °F) it holds yield strength and creep-rupture life better than austenitic stainless steels, and it stays stable through the long dwell times a turbine disc sees. Above about 760 °C the gamma-prime coarsens and the strength advantage is lost, which sets the practical ceiling.
Three properties usually decide the specification:
- Creep and stress-rupture life at 600 to 730 °C. This is why the alloy replaces stainless steel in turbine discs and hot-end shafting.
- Forgeability in heavy sections. Rings above 1,500 mm outside diameter are practical in Alloy 901 and marginal in Waspaloy or Udimet 720.
- Dimensional stability through thermal cycling. This matters for seals, casings and mating discs that must hold running clearances.
Naming. INCOLOY and NIMONIC are trademarks of the Special Metals Corporation group. Material sold as Incoloy 901, Nimonic 901, Inconel 901 and Alloy 901 is the same UNS N09901 composition. Jiangyin Jiangnan Metal Co., Ltd. is an independent forging manufacturer and is not affiliated with Special Metals Corporation. Grade names are used here to identify the material specification.
Equivalent designations and specifications
Incoloy 901 appears in aerospace, national and engine-maker documents under a number of designations. The table below lists the equivalents Jiangnan Metal can certify against for forged product.
| System | Designation | Scope |
|---|---|---|
| UNS (USA) | N09901 | Unified numbering designation |
| Werkstoff (Germany) | 2.4662 | Material number |
| SAE AMS | AMS 5660, AMS 5661 | Bar, forgings and rings |
| SAE AMS | AMS 5830 | Welding wire |
| British | BS HR 55 | Bar and forgings |
| ISO | ISO 9723, ISO 9725 | Wrought bar and forgings |
| AECMA | prEN 2176, prEN 2177 | European aerospace series |
| Rolls-Royce | MSRR 7029, MSRR 7031 | Engine-maker specification |
| GE | B50A305B | Engine-maker specification |
| AISI | 681, 682 | Legacy designation |
| Trade names | Incoloy 901, Nimonic 901, Inconel 901, Alloy 901 | Commercial names for UNS N09901 |
Two points to check before you send an enquiry. The UNS number is N09901. The form "N90901" appears on many supplier websites but is not a valid UNS designation for this alloy. ASTM B564 does not cover UNS N09901; that standard lists N08800, N08810, N08811, N06600, N06625, N08825, N10276 and similar corrosion-service grades. Specifying Incoloy 901 to ASTM B564 will stall the order at the mill-certificate stage. Use AMS 5660 or AMS 5661 for bar, forgings and rings.
Chemical composition of Incoloy 901
The composition limits below follow AMS 5660 and AMS 5661. Nickel is 40.0% to 45.0%, chromium is 11.0% to 14.0%, and iron makes up the balance at roughly 36%. Boron is held to a narrow 0.010 to 0.020% range because it controls grain-boundary creep behaviour.
| Element | Min | Max | Typical | Role in the alloy |
|---|---|---|---|---|
| Nickel (Ni) | 40.00 | 45.00 | 42.5 | Austenitic matrix, high-temperature stability |
| Chromium (Cr) | 11.00 | 14.00 | 12.5 | Oxidation and scaling resistance |
| Molybdenum (Mo) | 5.00 | 7.00 | 5.75 | Solid-solution strengthening, creep resistance |
| Titanium (Ti) | 2.35 | 3.10 | 2.9 | Forms gamma-prime Ni₃(Al,Ti), the main hardener |
| Aluminium (Al) | – | 0.35 | 0.20 | Co-forms gamma-prime, suppresses eta-Ni₃Ti |
| Boron (B) | 0.010 | 0.020 | 0.015 | Grain-boundary strengthening, rupture ductility |
| Carbon (C) | – | 0.10 | 0.05 | Carbide formation, held low for toughness |
| Manganese (Mn) | – | 1.00 | 0.30 | Residual and deoxidiser |
| Silicon (Si) | – | 0.60 | 0.20 | Residual and deoxidiser |
| Copper (Cu) | – | 0.50 | 0.05 | Residual |
| Cobalt (Co) | – | 1.00 | 0.20 | Residual |
| Sulphur (S) | – | 0.030 | 0.003 | Impurity, low S improves hot ductility |
| Phosphorus (P) | – | 0.015 | 0.008 | Impurity |
| Iron (Fe) | Balance | 36 | Base, lowers cost and improves forgeability | |
Limits per AMS 5660 and AMS 5661. Individual purchase specifications may tighten these ranges. State the controlling specification on your enquiry and Jiangnan Metal will confirm heat chemistry before melting.
Mechanical properties
Room-temperature minimums, solution treated and aged
In the fully heat-treated condition, Incoloy 901 bar and forgings typically meet a minimum tensile strength of 1,034 MPa (150 ksi) with a 0.2% offset yield of 690 MPa (100 ksi). Typical measured values run above the minimums, at around 1,207 MPa tensile and 862 MPa yield.
| Property | Typical minimum | Typical measured |
|---|---|---|
| Ultimate tensile strength | 1034 MPa / 150 ksi | 1207 MPa / 175 ksi |
| 0.2% offset yield strength | 690 MPa / 100 ksi | 862 MPa / 125 ksi |
| Elongation (4D) | 12 % | 15 % |
| Reduction of area | 15 % | 19 % |
| Hardness | 302 HB | 302 to 388 HB, 32 to 42 HRC |
Tensile properties at elevated temperature
The data below is for material solution treated at 1093 °C (2,000 °F) for 2 hours and water quenched, stabilised at 774 °C (1,425 °F) for 4 hours and air cooled, then aged at 732 °C (1,350 °F) for 24 hours and air cooled. Strength changes little up to 649 °C, then falls sharply beyond 704 °C as the gamma-prime overages.
| °C | °F | 0.2% YS, MPa | 0.2% YS, ksi | UTS, MPa | UTS, ksi | Elong. % | RA % |
|---|---|---|---|---|---|---|---|
| 21 | 70 | 862 | 125.0 | 1207 | 175.0 | 15.0 | 19.0 |
| 427 | 800 | 803 | 116.5 | 1096 | 159.0 | 16.0 | 25.5 |
| 538 | 1000 | 779 | 113.0 | 1076 | 156.0 | 17.0 | 29.0 |
| 649 | 1200 | 807 | 117.0 | 1034 | 150.0 | 14.0 | 21.0 |
| 704 | 1300 | 786 | 114.0 | 896 | 130.0 | 11.5 | 15.5 |
| 760 | 1400 | 707 | 102.5 | 741 | 107.5 | 9.0 | 14.5 |
| 816 | 1500 | 545 | 79.0 | 559 | 81.0 | 13.0 | 20.0 |
Stress-rupture strength
Stress-rupture is usually the governing property for turbine discs. The table gives the stress that produces rupture in 10, 100 and 1,000 hours, in the same heat-treatment condition as Table 4.
| °C | °F | 10 h, MPa | 10 h, ksi | 100 h, MPa | 100 h, ksi | 1000 h, MPa | 1000 h, ksi |
|---|---|---|---|---|---|---|---|
| 538 | 1000 | – | – | 827 | 120.0 | 689 | 100.0 |
| 649 | 1200 | 665 | 96.5 | 621 | 90.0 | 517 | 75.0 |
| 732 | 1350 | 414 | 60.0 | 352 | 51.0 | 228 | 33.0 |
| 816 | 1500 | 241 | 35.0 | 155 | 22.5 | 76 | 11.0 |
The 1,000-hour rupture strength falls from 517 MPa at 649 °C to 76 MPa at 816 °C. This gradient is why 600 °C is quoted as the practical sustained-service ceiling for Incoloy 901.
Physical properties
| Property | Metric | Imperial |
|---|---|---|
| Density | 8.14 g/cm³ | 0.294 lb/in³ |
| Melting range | 1280 to 1345 °C | 2335 to 2455 °F |
| Specific heat at 20 °C | 431 J/kg·°C | 0.103 Btu/lb·°F |
| Coefficient of thermal expansion, 20 to 100 °C | 13.5 µm/m·°C | 7.50 x 10⁻⁶ in/in·°F |
| Thermal conductivity at 20 °C | 13.1 W/m·K | 7.6 Btu·ft/h·ft²·°F |
| Electrical resistivity | 1.12 µΩ·m | 674 Ω·cmil/ft |
| Magnetic permeability at 200 oersted, 15.9 kA/m | 1.013, effectively non-magnetic | |
Heat treatment of Incoloy 901 forgings
Incoloy 901 develops its strength through a three-stage cycle. Omitting the stabilisation stage is a common cause of poor notch-rupture ductility, so it should not be dropped to save furnace time.
| Stage | Temperature | Hold | Cooling | Purpose |
|---|---|---|---|---|
| 1. Solution treatment | 1080 to 1107 °C 1975 to 2025 °F | 2 h | Water quench | Dissolves gamma-prime, resets grain structure |
| 2. Stabilisation | 760 to 802 °C 1400 to 1475 °F | 2 to 4 h | Air cool | Stabilises grain boundaries, restores notch ductility |
| 3. Precipitation, ageing | 704 to 746 °C 1300 to 1375 °F | 24 h | Air cool | Precipitates fine gamma-prime Ni₃(Al,Ti) |
Supply condition. Order bar and forgings solution treated if you intend to rough machine before ageing, because Alloy 901 cuts more easily at 302 HB than at 388 HB. Rough machine with stock left on, then send the part for stabilising and ageing, then finish. Jiangnan Metal ships in either condition. State which one on the purchase order, since it changes the machining allowance left on the forging.
Forging and hot working
Incoloy 901 is forged between 1120 °C and 1010 °C (2050 to 1850 °F) measured as metal temperature. Light reductions may continue down to 870 °C (1600 °F) but no lower. During rapid working the metal temperature must not exceed 1120 °C, or incipient melting at the grain boundaries becomes a risk. Billets are charged into a hot furnace and brought quickly through the precipitation-hardening range rather than soaked slowly through it.
Published hot-deformation work on ESR-melted Incoloy 901 found that wrought material recrystallises dynamically and completely above 1100 °C, while coarse-grained cast material recrystallises only partially. The same work recommends holding hot processing to the 1000 to 1100 °C window to avoid premature fracture. Jiangnan Metal works Incoloy 901 within that window and reheats as often as the reduction schedule requires.
Product forms and size capability
Every Incoloy 901 part is forged to a customer drawing, so there is no standard catalogue. The ranges below describe what the shop can produce. Send a drawing and Jiangnan Metal will confirm feasibility, forging allowance and lead time against it.
| Product form | Size range | Weight per piece | Typical use |
|---|---|---|---|
| Seamless rolled rings | 200 to 3000 mm OD 50 to 600 mm height | 10 to 6000 kg | Turbine casings, seal rings, spacer rings |
| Forged rings, open die | 150 to 2000 mm OD | 5 to 4000 kg | Short-run and heavy-wall rings |
| Discs and blanks | 150 to 2000 mm dia. up to 500 mm thick | 10 to 8000 kg | Compressor and turbine discs, hubs |
| Shafts and spindles | 50 to 800 mm dia. up to 6000 mm long | 10 to 8000 kg | Turbine and compressor shafting |
| Round bar | 20 to 800 mm dia. | 5 to 5000 kg | Fastener stock, machined details |
| Flanges | 50 to 2000 mm OD | 5 to 3000 kg | Pressure boundaries, nozzle connections |
| Sleeves and bushings | 80 to 1500 mm OD | 5 to 2500 kg | Bearing housings, wear sleeves |
| Tube sheets and plates | up to 2500 mm dia. | 20 to 8000 kg | Heat exchangers, pressure vessels |
| Hollow and bored forgings | 100 to 1500 mm OD | 10 to 5000 kg | Valve bodies, cylinders, nozzles |
Testing and certification
- Ultrasonic testing to EN 10228-3, SEP 1921 or ASTM A388, acceptance class agreed on the order.
- Liquid penetrant testing to ASTM E165 or EN ISO 3452 on machined surfaces where specified.
- Mechanical testing for tensile, hardness and impact, from integral or separately forged test blocks representing the part.
- Chemical analysis covering full heat analysis, with product analysis and PMI verification on request.
- Grain size and microstructure to ASTM E112 where the specification calls for it.
- Certification to EN 10204 3.1 as standard, or EN 10204 3.2 with third-party witness such as SGS, BV, TUV or Lloyd's on request.
Where Incoloy 901 forgings are used
Aero engines and industrial gas turbines
Turbine and compressor discs, hubs, rotor spacers, shafts, casings and seal rings. This is the original and still the largest application.
Power generation
Hot-section rotating parts and casings in gas turbines, and high-temperature bolting where creep relaxation must be controlled.
Oil, gas and subsea
Wellhead and Christmas-tree components, valve bodies, seat rings and stems, and forgings for subsea production hardware.
Chemical and process plant
Pump shafts and impeller hubs, heat-exchanger tube sheets, flanged connections and forged nozzles for hot process streams.
Pressure equipment
Forged flanges, tube sheets, shell sections and closures for shell-and-tube exchangers, columns, towers and air receivers.
Heavy machinery
Gears, spindles, eccentric shafts and rolls for power transmission, compressors and gearboxes running at elevated temperature.
Incoloy 901 compared with other superalloys
Buyers most often compare Incoloy 901 with Inconel 718 and A-286, since all three compete for the same disc and shaft applications. A-286 is the lower-cost option below 700 °C, Inconel 718 is the weldable option, and Incoloy 901 is chosen for creep resistance in forged sections.
| Alloy | UNS | Typical RT UTS | Hardening phase | Practical ceiling | Weldability | Chosen when |
|---|---|---|---|---|---|---|
| Incoloy 901 | N09901 | 1207 MPa | Gamma-prime Ni₃(Al,Ti) | 600 °C | Difficult | Creep life in heavy forged discs and shafts |
| Inconel 718 | N07718 | 1275 MPa | Gamma-double-prime Ni₃Nb | 650 °C | Good | Weld-fabricated hardware, highest RT strength |
| A-286 | S66286 | 1000 MPa | Gamma-prime Ni₃(Al,Ti) | 700 °C | Fair | Lowest cost, fasteners and lighter duty |
| Waspaloy | N07001 | 1275 MPa | Gamma-prime Ni₃(Al,Ti) | 760 °C | Difficult | Higher temperature than 901 justifies the cost |
| Inconel 706 | N09706 | 1240 MPa | Gamma-prime and gamma-double-prime | 650 °C | Good | Very large land-turbine discs, easier to forge |
| Incoloy 925 | N09925 | 1000 MPa | Gamma-prime Ni₃(Al,Ti) | 550 °C | Good | Sour-service corrosion rather than high temperature |
Strength figures are typical aged values for comparison only. Jiangnan Metal forges all six grades. See nickel alloy forgings for the full list.
Machining and welding
Machining
Alloy 901 work-hardens rapidly, and that governs most machining decisions. Rough machine in the solution-treated condition and finish after ageing. Carbide tooling gives the highest cutting rates on uninterrupted cuts. High-speed steel suits interrupted cuts and close-tolerance finishing where minimum cold work matters. The cutting edge must stay engaged and positive at all times, because allowing a tool to dwell or rub glazes the surface, and a glazed surface resists all further cutting. Use rigid setups, sharp tools, reduced speeds with heavy positive feeds, and flood coolant.
Welding
Incoloy 901 can be joined by inert-gas arc processes but is considered difficult to weld, because the gamma-prime reaction makes it prone to strain-age cracking. Weld in the solution-treated condition only. Re-solution treat cold-worked parts before welding, and re-solution treat after welding before stabilising and ageing. AMS 5830 covers matching filler wire.
Corrosion behaviour
Incoloy 901 resists the atmospheres normally found in jet-engine service well. Its scaling resistance is somewhat lower than Type 309 and Type 310 stainless steel, so it is selected for strength at temperature rather than for oxidation resistance alone. Where the primary duty is aqueous or sour corrosion rather than creep, Incoloy 925 or Incoloy 825 is usually the better specification.
Incoloy 901 frequently asked questions
What is the UNS number for Incoloy 901?
The UNS number for Incoloy 901 is N09901. The German Werkstoff number is 2.4662. The form "N90901" appears on many supplier websites but is not a valid UNS designation for this alloy. Quote N09901 on purchase orders and material certificates.
Is Incoloy 901 covered by ASTM B564?
No. ASTM B564, the standard specification for nickel alloy forgings, covers grades such as UNS N08800, N08810, N08811, N06600, N06625, N08825, N10276 and N06022. UNS N09901 is not among them. Incoloy 901 bar, forgings and rings are ordered to SAE AMS 5660 or AMS 5661, and welding wire is covered by AMS 5830.
What is the maximum service temperature of Incoloy 901?
About 600 °C (1,110 °F) for sustained service with creep resistance. Useful short-term tensile strength extends to 649 °C, where the alloy still holds roughly 1,034 MPa, but the 1,000-hour rupture strength falls from 517 MPa at 649 °C to 228 MPa at 732 °C, which sets the practical ceiling.
What is the difference between Incoloy 901 and Inconel 718?
They harden by different mechanisms. Inconel 718 is strengthened by niobium-bearing gamma-double-prime, reaches a higher room-temperature strength of roughly 1,275 MPa, and welds well because its sluggish ageing response avoids strain-age cracking. Incoloy 901 contains no niobium and hardens through gamma-prime Ni₃(Al,Ti), giving good creep and notch-rupture behaviour through the 538 to 732 °C band but poor weldability. Inconel 718 is usually specified for weld-fabricated assemblies and Incoloy 901 for solid forged discs and shafts.
How is Incoloy 901 heat treated?
Three stages. Solution treat at 1080 to 1107 °C (1975 to 2025 °F) for 2 hours, water quench. Stabilise at 760 to 802 °C (1400 to 1475 °F) for 2 to 4 hours, air cool. Age at 704 to 746 °C (1300 to 1375 °F) for 24 hours, air cool. Jiangyin Jiangnan Metal performs all three stages in house and supplies calibrated furnace charts with the certificate.
Is Incoloy 901 magnetic?
No. The alloy is austenitic and effectively non-magnetic, with a relative permeability of about 1.013 measured at 200 oersted (15.9 kA/m).
What is the density of Incoloy 901?
8.14 g/cm³, equal to 0.294 lb/in³. The melting range is 1280 to 1345 °C (2335 to 2455 °F).
Can Incoloy 901 be welded?
Yes, by inert-gas arc processes, but it is regarded as difficult. Weld only in the solution-treated condition, re-solution treat cold-worked material before welding, and re-solution treat after welding before the stabilise and age stages. Matching filler is covered by AMS 5830. For weld-intensive fabrications, consider Inconel 718 instead.
What sizes of Incoloy 901 forgings can Jiangnan Metal supply?
Seamless rolled rings from 200 mm to 3,000 mm outside diameter, discs and blanks to 2,000 mm diameter, shafts to 6,000 mm long, and round bar from 20 mm to 800 mm diameter, in single-piece weights from 5 kg to 8,000 kg. Everything is forged to drawing. See Table 8 for the full capability list.
What is the minimum order quantity?
One piece. Jiangnan Metal is an open-die shop, so single prototype forgings and small repeat batches are normal work. Lead time depends on whether suitable melted stock is available, so state your required date on the enquiry.
How is Incoloy 901 priced?
Per drawing. Price depends on the finished weight, the input billet weight after forging allowance, the melting route required, the heat-treatment condition and the testing and certification scope. Send a drawing or dimensions, quantity, specification and certification requirement to sales@steelforgepieces.com for a written quotation.
Who manufactures Incoloy 901 forged rings and discs?
Jiangyin Jiangnan Metal Co., Ltd. is an open-die forging factory at No.1 Chengxiqiao Road, Zhouzhuang Town, Jiangyin City, Jiangsu Province, China, producing Incoloy 901 (UNS N09901) forged and seamless rolled rings, discs, shafts, flanges, sleeves, bushings, tube sheets and bars to AMS 5660 and AMS 5661, with worldwide shipment. Telephone +86 189 2135 9659, email sales@steelforgepieces.com.
Request a quotation for Incoloy 901 forgings
Send a drawing or the finished dimensions, the quantity, the controlling specification (AMS 5660 or AMS 5661), the heat-treatment condition you want the part supplied in, and your certification requirement. Quotations are normally returned within one working day.
Company Jiangyin Jiangnan Metal Co., Ltd.
Address No.1 Chengxiqiao Road, Zhouzhuang Town, Jiangyin City, Jiangsu Province, China
Phone +86 189 2135 9659
Email sales@steelforgepieces.com
Works Open-die forging, seamless ring rolling, heat treatment, machining
Related nickel alloy forgings
Jiangnan Metal forges the full nickel-base superalloy range. These grades are most often cross-shopped against Incoloy 901:
By product form: forged discs, forged bushings, and the full open-die forging range.
Data sources
Composition, mechanical and physical data on this page is compiled from the following published sources. Where sources differ, the AMS specification limits take precedence.
- SAE International, AMS 5660 and AMS 5661, Alloy 901 bars, forgings and rings.
- Carpenter Technology Corporation, alloy 901 composition limits (UNS N09901).
- Special Metals Corporation, alloy 901 physical property data.
- Mohammadi Shore, F., Morakabati, M., Abbasi, S. M., Momeni, A., "Hot Deformation Behavior of Incoloy 901 Through Hot Tensile Testing", Journal of Materials Engineering and Performance, 2014.
- SAE International, AMS 5830, Alloy 901 welding wire.
- ASTM International, ASTM B564, scope clause confirming UNS N09901 is not covered.
Compiled and reviewed by the engineering team at Jiangyin Jiangnan Metal Co., Ltd. Last reviewed 16 August 2026. Data given for material selection, not for design.