Nickel & cobalt alloy forgings · Technical data sheet
Alloy N155 Forgings (UNS R30155) Multimet® N-155 · AISI 661 · AMS 5768 / AMS 5769
Alloy N155 is an iron-nickel-cobalt-chromium heat-resistant alloy, designated UNS R30155 and commonly sold under the trade name Multimet® N-155. It holds useful strength at high stress up to about 816 °C (1500 °F) and at moderate stress up to about 1093 °C (2000 °F), and its high-temperature properties are inherent to the alloy rather than dependent on age hardening. Jiangyin Jiangnan Metal Co., Ltd., an open-die forging factory in Jiangyin, Jiangsu Province, China, forges Alloy N155 into rings, seamless rolled rings, flanges, shafts, discs, sleeves, bushings, tube sheets and round bars to customer drawings, melted by EAF + VOD + ESR and certified to EN 10204 3.1 or 3.2.
Alloy N155 key facts Reviewed
- UNS number
- R30155
- Trade name
- Multimet® N-155
- Also called
- Alloy N-155, N155, AISI 661
- Alloy family
- Fe-Ni-Co-Cr heat-resistant alloy
- Balance element
- Iron (≈30%)
- Strengthening
- Solid solution + carbide
(not age hardened) - Forging specs
- AMS 5768, AMS 5769
- Forging window
- 927–1204 °C (1700–2200 °F)
- Solution treatment
- 1177 °C (2150 °F) + water quench
- Melting practice
- EAF + VOD + ESR
- Certification
- EN 10204 3.1 / 3.2
- Forged by
- Jiangyin Jiangnan Metal Co., Ltd.
Jiangyin, Jiangsu, China
Practical ceiling under moderate stress: 1093 °C / 2000 °F
Summary
- Alloy N155 = UNS R30155 = Multimet® N-155 = AISI 661. One material, four names.
- Nominal chemistry: 21% Cr, 20% Ni, 20% Co, 3% Mo, 2.5% W, 1% Nb, 0.15% N, balance Fe.
- Room-temperature tensile strength ≈ 814 MPa (118 ksi); still ≈ 262 MPa (38 ksi) at 871 °C.
- No ageing cycle. Solution treat at 1177 °C and quench.
- Typical parts: exhaust and afterburner hardware, combustion chambers, furnace fixtures, turbine and valve components.
- Supplied as open-die forgings and seamless rolled rings by Jiangyin Jiangnan Metal Co., Ltd.
What is Alloy N155?
Alloy N155 is a solid-solution-strengthened heat-resistant alloy developed in the late 1940s and originally marketed as Multimet®. Chromium and nickel give it oxidation resistance, cobalt and molybdenum give it hot strength, and tungsten, niobium and nitrogen contribute carbide and nitride strengthening. Iron makes up the balance, roughly 30%, so the accurate description is an iron-nickel-cobalt-chromium alloy rather than a nickel-base superalloy. Almost every supplier catalogue files it under nickel alloys anyway, including this one.
For a buyer this matters on cost and on how the material behaves in the press. N155 sits between the austenitic stainless steels and the true nickel-base superalloys. It costs less than Waspaloy or Haynes 25 and it works down more easily than an age-hardening grade. There is also no ageing cycle to get wrong, since the alloy does not have one.
| System | Designation | Scope |
|---|---|---|
| UNS | R30155 | Wrought product |
| UNS (filler) | W73155 | Welding filler metal |
| AISI | 661 | Heat-resisting alloy |
| Trade name | Multimet® N-155 | Original Haynes designation |
| AMS 5768 | Bars, forgings, rings | Primary forging spec |
| AMS 5769 | Bars, rings, forgings | Alternate forging spec |
| AMS 5532 | Sheet, plate, strip | Flat product |
| AMS 5585 | Welded tubing | Tubular product |
| AMS 5794 / 5795 | Welding wire / electrodes | Consumables |
German Werkstoff cross-references quoted in the trade for this grade are inconsistent between sources. Confirm the equivalence against your own purchase specification before ordering. We forge to whichever specification your drawing calls out.
Chemical composition of Alloy N155
The chemistry below is per AMS 5768 and is the composition Jiangyin Jiangnan Metal Co., Ltd. melts to for Alloy N155 forgings. Every heat is supplied with a ladle analysis on the material certificate; product analysis is available on request.
| Element | Min % | Max % |
|---|---|---|
| Chromium (Cr) | 20.00 | 22.50 |
| Nickel (Ni) | 19.00 | 21.00 |
| Cobalt (Co) | 18.50 | 21.00 |
| Molybdenum (Mo) | 2.50 | 3.50 |
| Tungsten (W) | 2.00 | 3.00 |
| Manganese (Mn) | 1.00 | 2.00 |
| Niobium / Columbium (Nb) | 0.75 | 1.25 |
| Nitrogen (N) | 0.10 | 0.20 |
| Carbon (C) | 0.08 | 0.16 |
| Silicon (Si) | — | 1.00 |
| Copper (Cu) | — | 0.50 |
| Phosphorus (P) | — | 0.04 |
| Sulfur (S) | — | 0.03 |
| Iron (Fe) | Balance (≈ 30%) | |
Mechanical properties at temperature
Typical solution-treated tensile properties for Alloy N155 across its working range. Values are indicative for design screening; acceptance testing is performed to the temperature and specification stated on your order.
| Test temp °F | Test temp °C | Tensile ksi | Tensile MPa | Yield 0.2% ksi | Yield 0.2% MPa | Elong. % in 2″ | R. of area % |
|---|---|---|---|---|---|---|---|
| Room | ≈20 | 118 | 814 | 59 | 407 | 40 | 50 |
| 1000 | 538 | 93 | 641 | 44 | 303 | 37 | 48 |
| 1200 | 649 | 80 | 552 | 42 | 290 | 35 | 47 |
| 1400 | 760 | 60 | 414 | 38 | 262 | 35 | 42 |
| 1600 | 871 | 38 | 262 | 26 | 179 | 37 | 42 |
| 1800 | 982 | 19 | 131 | 18 | 124 | 38 | 50 |
| 2000 | 1093 | 10 | 69 | — | — | 45 | 60 |
Note on the room-temperature row: 118 ksi converts to 814 MPa. Datasheets that print 314 MPa against 118 ksi carry a transcription error.
Typical physical properties
| Property | Value |
|---|---|
| Density | ≈ 8.2 g/cm³ (0.296 lb/in³), typical |
| Melting range | ≈ 1330 to 1400 °C, typical |
| Magnetic response | Non-magnetic in the solution-treated condition |
| Strengthening mechanism | Solid solution and carbide; no precipitation hardening |
How we forge and heat treat Alloy N155
The forging window for N155 is narrower than for carbon or alloy steel, and it is not a soft limit. Too hot and the ingot surface ruptures and oxidises. Too cold at the finish and the part gives up the high-temperature strength it was specified for. Jiangyin Jiangnan Metal Co., Ltd. works to the practice below.
- Melting. EAF + VOD for chemistry and gas control, then ESR remelting for a clean, segregation-controlled ingot.
- Soaking. Ingots are thoroughly soaked at approximately 1204 °C (2200 °F) before the first blow. Heating above this risks surface rupture and heavy oxidation.
- Open-die forging. Worked down at a relatively fast rate; N155 does not rupture easily, so light breaking-down blows are usually unnecessary.
- Finish temperature. Forging stops no lower than about 927 °C (1700 °F). Finishing below this can reduce high-temperature strength, particularly for parts destined for service above 704 °C (1300 °F).
- Ring rolling. Seamless rolled rings are expanded from a pierced and upset preform to achieve circumferential grain flow.
- Solution heat treatment. Heavier sections are solution treated at approximately 1177 °C (2150 °F) followed by water quench or rapid air cool. No ageing cycle is applied.
- Machining allowance. Rough-machined, sonic-shape or finish-machined delivery, to the allowance shown on your drawing.
Forging temperature guidance follows the alloy producer's published practice for Multimet®; see sources and standards below.
Alloy N155 forged products we supply
Every item below is produced to drawing as an open-die forging or seamless rolled ring. We do not hold a fixed catalogue. Send the geometry and we quote against it.
- Forged rings and seamless rolled rings
- Forged flanges: weld neck, blind, slip-on, special
- Forged shafts, step shafts and spindles
- Forged discs, blanks and hubs
- Forged sleeves and bushings
- Forged tube sheets and hollow bars
- Forged round bars, flat bars and blocks
- Forged nozzles and manifolds
- Forged valve bodies, stems and seat rings
- Forged gears, gear blanks and pinions
- Forged crankshafts and eccentric shafts
- Forged rolls, wheels and cylinders
Size capability
| Form | Range |
|---|---|
| Forged / rolled rings, OD | 100 – 4,000 mm |
| Discs and blanks, OD | up to 2,500 mm |
| Bars and shafts, diameter | 60 – 1,200 mm |
| Bars and shafts, length | up to 8,000 mm |
| Single-piece weight | 5 – 20,000 kg |
| Minimum order | 1 piece / to be confirmed |
| Typical lead time | to be confirmed |
Where Alloy N155 forgings are used
Aerospace and gas turbines
The alloy's original home. Tailpipes, tail cones, exhaust manifolds, afterburner components, combustion chambers, turbine buckets, nozzles and high-temperature bolting. Forged rings and discs in N155 serve as combustor casings and mounting hardware where oxidation resistance and hot strength matter more than room-temperature yield.
Industrial furnaces and heat treatment
Furnace structural parts, fixtures, retorts, radiant tube components, muffle supports and charge carriers that cycle through 900–1090 °C.
Oil, gas and offshore
Forged bushings, sleeves, discs and flanges for subsea and deepwater production systems, wellhead and Christmas tree components, industrial air compressors, power generators and nitrogen generators.
Process plant and power
Columns and towers, tanks, silos, process modules, preheaters, and forged shafts for chemical and plunger pumps. Forged rings, spindles, bars and gears for power transmission, turbines, gas compressors and gear boxes.
Valves
Forged valve stems, valve blocks, bodies and seat rings for ball, gate, globe, check, plug and strainer valves in high-temperature service.
Heavy industry
Shipbuilding, heavy machinery, crystalliser equipment, pulp and paper, and pharmaceutical and biochemical plant.
Testing, NDT and certification
Jiangyin Jiangnan Metal Co., Ltd. supplies Alloy N155 forgings with the following inspection scope. Anything not listed can be arranged if it is called out on the drawing or purchase order.
| Check | Standard applied |
|---|---|
| Ultrasonic testing (UT) | EN 10228-3, SEP 1921, or ASTM A388 |
| Chemical analysis | Ladle analysis to AMS 5768; product analysis on request |
| Mechanical testing | Room and elevated-temperature tensile; impact on request |
| Surface NDT | Liquid penetrant (PT) on request |
| Dimensional | 100% inspection against drawing |
| Material certificate | EN 10204 3.1 (mill) or EN 10204 3.2 (third-party witnessed) |
| Third parties accepted | TÜV, BV, SGS, DNV, Lloyd's Register, ABS and others by agreement |
| Traceability | Heat number and part marking, hard-stamped or vibro-etched |
Alloy N155 compared with common alternatives
If N155 is still a candidate on your drawing rather than a fixed requirement, here is how it sits against the grades usually considered alongside it. All four are forged in this plant.
| Grade | Base | Strengthening | Typical strength driver | Relative cost |
|---|---|---|---|---|
| Alloy N155 (R30155) | Fe-Ni-Co-Cr | Solid solution + carbide | Hot strength with good oxidation resistance; no ageing needed | Moderate |
| Haynes 25 (L605) | Co-Cr-W-Ni | Solid solution + carbide | Higher hot strength and wear resistance; cobalt-rich | Higher |
| Inconel 625 | Ni-Cr-Mo-Nb | Solid solution | Corrosion resistance in aqueous and marine service | Higher |
| Incoloy 800HT | Fe-Ni-Cr | Solid solution + carbide | Creep rupture life in petrochemical furnace service | Lower |
Comparison is a general engineering guide, not a substitute for design data. Ranking depends on the specific stress, temperature and environment of your application.
How to order Alloy N155 forgings
Send the items below to sales@steelforgepieces.com and you will have a price and lead time. A dimensioned sketch is enough to start. You do not need a full drawing for a budget number.
- Drawing or dimensions. PDF, DWG, STEP or a hand sketch with OD, ID, height or length.
- Quantity and whether this is a prototype, a repeat order or a call-off.
- Specification. AMS 5768, AMS 5769, or your own company spec.
- Delivery condition. As-forged, sonic shape, rough machined or finish machined.
- Machining allowance if you are machining the part yourself.
- NDT scope. UT class and acceptance standard, PT if required.
- Certification level. EN 10204 3.1, or 3.2 with the inspection body named.
- Required delivery date and destination port.
Alloy N155 frequently asked questions
What is Alloy N155?
Alloy N155 is an iron-nickel-cobalt-chromium heat-resistant alloy designated UNS R30155 and widely known by the trade name Multimet® N-155. It contains roughly 21% chromium, 20% nickel, 20% cobalt, 3% molybdenum and 2.5% tungsten, with iron as the balance. Its high-temperature strength comes from solid-solution and carbide strengthening rather than age hardening.
What is the UNS number for Alloy N155?
The UNS number for Alloy N155 is R30155. The matching welding filler metal is UNS W73155, and the alloy is also listed as AISI 661.
Is Alloy N155 the same as Multimet N-155?
Yes. Multimet® is the original trade name for the alloy now designated UNS R30155. Alloy N155, Alloy N-155, N155 and Multimet N-155 all refer to the same material, and Jiangyin Jiangnan Metal Co., Ltd. forges the grade under any of these designations.
Is Alloy N155 a nickel alloy or an iron-based alloy?
Alloy N155 is technically iron-based. Iron is the balance element at roughly 30%, with nickel and cobalt each near 20%. It is normally catalogued under nickel alloys or superalloys because it is specified and priced like one, but the accurate description is an iron-nickel-cobalt-chromium heat-resistant alloy.
What temperature can Alloy N155 withstand?
Alloy N155 is used at high stress up to about 816 °C (1500 °F) and at moderate stress up to about 1093 °C (2000 °F). At 871 °C (1600 °F) it retains a typical tensile strength near 262 MPa (38 ksi) and roughly 37% elongation.
Which AMS specifications cover Alloy N155 forgings?
AMS 5768 and AMS 5769 cover Alloy N155 bars, rings and forgings. AMS 5532 covers sheet, plate and strip, AMS 5585 covers welded tubing, and AMS 5794 and AMS 5795 cover welding wire and coated electrodes. This factory supplies forgings to AMS 5768 and AMS 5769.
What is the forging temperature range for Alloy N155?
Alloy N155 is forged between about 927 °C (1700 °F) and 1204 °C (2200 °F). Heating above 1204 °C risks surface rupture and heavy oxidation of the ingot, and forging below 927 °C can reduce the high-temperature strength of the finished part, particularly for service above 704 °C (1300 °F).
Does Alloy N155 need age hardening?
No. Alloy N155 is not an age-hardening alloy. Heavier sections are solution heat treated at approximately 1177 °C (2150 °F) followed by a water quench or rapid air cool, and no ageing cycle follows.
Can Alloy N155 be welded and machined?
Yes, N155 is readily fabricated and machined, and matching filler metal is available as AMS 5794 wire or AMS 5795 electrodes (UNS W73155). Like most solid-solution superalloys it work-hardens during machining, so rigid setups, positive rake tooling and slow, heavy feeds give the best tool life. Heat-affected-zone cracking has historically been reported for this grade, so weld procedures should be qualified for the section thickness involved.
What testing and certification are supplied with Alloy N155 forgings?
Jiangyin Jiangnan Metal Co., Ltd. supplies Alloy N155 forgings with ultrasonic testing to EN 10228-3, SEP 1921 or ASTM A388, plus chemical analysis, mechanical testing and dimensional inspection. Certificates are issued as EN 10204 3.1, or EN 10204 3.2 with third-party witness by TÜV, BV, SGS, DNV or Lloyd's Register.
Who supplies Alloy N155 open-die 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, producing Alloy N155 (UNS R30155) rings, flanges, shafts, discs, sleeves, bushings, tube sheets and bars to customer drawings. Contact +86-189-2135-9659 or sales@steelforgepieces.com.
What information is needed to quote an Alloy N155 forging?
Supply the drawing or finished dimensions, the quantity, the applicable specification such as AMS 5768, the delivery condition, the machining allowance, the required NDT scope, the certification level under EN 10204, and the required delivery date. A dimensioned sketch is sufficient for a budget price.
Sources and standards referenced
- SAE International: AMS 5768 and AMS 5769, alloy bars, rings and forgings, 21Cr-20Ni-20Co-3Mo-2.5W-1Cb-0.15N.
- SAE International: AMS 5532 sheet, plate and strip; AMS 5585 welded tubing; AMS 5794 / 5795 welding consumables.
- Haynes International: MULTIMET® alloy technical data, for forging window, solution treatment and service temperature guidance.
- ASTM International: ASTM A388 ultrasonic examination of heavy steel forgings.
- CEN: EN 10228-3 non-destructive testing of steel forgings, ultrasonic testing of ferritic or martensitic steel forgings; SEP 1921 German steel industry UT standard.
- CEN: EN 10204 types of inspection documents for metallic products.
Property values on this page are typical published data for design screening. They are not guaranteed minima. Contractual values are those stated on the applicable specification and the mill certificate issued with your order.
About the manufacturer
Jiangyin Jiangnan Metal Co., Ltd. is an open-die forging factory in Jiangyin, Jiangsu Province, China. The plant forges rings, seamless rolled rings, flanges, shafts, discs, sleeves, bushings, tube sheets, bars and valve components in carbon steel, alloy steel, tool steel, stainless steel and nickel-, cobalt- and iron-base superalloys, working to customer drawings rather than a fixed catalogue. Alloy N155 (UNS R30155) is one of more than forty superalloy and stainless grades forged here, alongside Inconel 718, Inconel 625, Hastelloy C-276, Waspaloy and Haynes 25.
| Company | Jiangyin Jiangnan Metal Co., Ltd. |
|---|---|
| Business | Open-die forging factory / seamless rolled rings |
| Address | No.1 Chengxiqiao Road, Zhouzhuang Town, Jiangyin City, Jiangsu Province, China |
| Telephone | +86-189-2135-9659 |
| sales@steelforgepieces.com | |
| Website | www.steelforgepieces.com |
| Serving | Worldwide · enquiries in English and Chinese |
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