NiCr23Fe at a glance
- Grade
- NiCr23Fe (Alloy 601)
- Werkstoff / EN number
- 2.4851
- UNS number
- N06601
- ISO designation
- NiCr23Fe15Al
- Alloy family
- Nickel-chromium-iron, austenitic, solid solution
- European standards
- DIN EN 10095, DIN 17742, VdTÜV 471
- Nickel
- 58.0–63.0 %
- Chromium
- 21.0–25.0 %
- Aluminium
- 1.00–1.70 %
- Max continuous service in air
- 1200 °C (2192 °F) per EN 10095
- Delivery condition
- Solution annealed 1100–1180 °C, rapid cooled
- Density
- 8.11 g/cm³ (0.293 lb/in³)
- Melting range
- 1360–1411 °C (2480–2571 °F)
- Certification
- EN 10204 3.1 standard, 3.2 third-party witnessed
- Forged forms
- Rolled rings, flanges, bars, discs, shafts, sleeves, bushings, tube sheets
- Forged by
- Jiangyin Jiangnan Metal Co., Ltd., Jiangyin, Jiangsu, China
Material description and selection
In the German Werkstoff system the short name NiCr23Fe describes a nickel base with nominally 23% chromium and iron as the next significant element. The numeric equivalent is 2.4851. Composition limits and scaling limits are set in DIN EN 10095, the European standard for heat-resisting steels and nickel alloys. Outside Europe the same alloy is bought as UNS N06601 or as Alloy 601.
The 1.0–1.7% aluminium content is the reason the grade costs more than a plain nickel-chromium alloy. Chromium on its own protects by forming Cr₂O₃, which is effective to about 1000–1100 °C. Above that range Cr₂O₃ volatilises as CrO₃ and the scale thins. Aluminium forms a thin continuous Al₂O₃ layer under the chromia. Al₂O₃ does not volatilise at these temperatures, it stays adherent, and it re-forms if the surface is damaged. Scale therefore survives repeated heating and cooling without spalling, which is the usual failure mode of furnace hardware.
Specify NiCr23Fe where the part sees air, combustion gas or a carburising atmosphere above about 1000 °C and is thermally cycled. Below roughly 900 °C an iron-base grade such as Alloy 800HT is normally cheaper and adequate. Above 1200 °C with sustained load, consider Alloy 602 CA (2.4633) or Inconel 617.
NiCr23Fe is a solid-solution alloy. It is not precipitation hardened, so no ageing treatment is applied and forgings are supplied solution annealed. The grade also resists chloride-ion stress-corrosion cracking, high-purity water and caustics, so it is used in aqueous service as well as in furnaces. It is not suitable for strongly reducing sulfur-bearing atmospheres, where low-melting nickel-sulfur phases can form.
Process and service temperatures
Four temperatures control how a NiCr23Fe forging is made and how far it can be taken in service. They are shown together because specifying one without the others is a common source of ordering errors.
| Temperature | Significance |
|---|---|
| 980–1230 °C | Hot-working range. Forging finishes near the low end so the grain is not left coarse. |
| 1100–1180 °C | Solution annealing range, followed by rapid cooling. This is the delivery condition. |
| 1200 °C | Maximum continuous service temperature in air per DIN EN 10095, defined by an average scaling rate of no more than 1 g/m²·h. |
| 1250 °C | Oxidation resistance is still demonstrated at this level for short intermittent excursions, but design allowables are effectively zero. |
| 650–870 °C | Range to pass through quickly on cooling. Slow cooling here can precipitate carbides at grain boundaries and reduce ductility. |
| 1360–1411 °C | Melting range. |
Chemical composition of NiCr23Fe (2.4851 / UNS N06601)
The limits below are those of UNS N06601, the chemistry most widely accepted for this grade. Points where DIN EN 10095 is tighter or adds an element are listed under the table. Material is melted by EAF + VOD, with ESR remelting available. Each heat is checked by spectrometer against these limits before it is heated for forging.
| Element | Min % | Max % | Function |
|---|---|---|---|
| Nickel (Ni) | 58.00 | 63.00 | Stabilises the austenitic matrix; resistance to chloride stress-corrosion cracking and caustics |
| Chromium (Cr) | 21.00 | 25.00 | Forms the Cr₂O₃ scale against oxidation, sulfidation and hot corrosion |
| Aluminium (Al) | 1.00 | 1.70 | Forms the adherent Al₂O₃ sub-scale that keeps the alloy serviceable above 1000 °C |
| Iron (Fe) | - | balance | Balance, nominally about 14%. Holds cost below fully nickel-base grades |
| Carbon (C) | - | 0.10 | Carbide former, controlled for grain-size stability and weldability |
| Manganese (Mn) | - | 1.00 | Deoxidiser, combines with sulfur |
| Silicon (Si) | - | 0.50 | Deoxidiser, contributes to oxidation resistance |
| Copper (Cu) | - | 1.00 | Residual limit |
| Cobalt (Co) | - | 1.00 | Residual limit, restricted further for some nuclear work |
| Sulfur (S) | - | 0.015 | Kept low for hot workability and weldability |
Differences under DIN EN 10095
- Carbon is bracketed rather than only capped. EN 10095 requires 0.03–0.10% C, so a very low-carbon heat that passes UNS N06601 can fail the European standard.
- Iron is capped at 18% max instead of being left as an open balance.
- Further elements are limited: titanium 0.50% max, phosphorus 0.020% max, boron 0.006% max. Copper is often restricted to 0.50% max rather than 1.00%.
Order to one standard, not two. If the drawing calls up NiCr23Fe or 2.4851, state DIN EN 10095 on the purchase order and we certify to the European limits. If it calls up Alloy 601 or N06601, we certify to ASTM B166 chemistry. Dual certification is possible but has to be agreed before the heat is selected, because the carbon minimum and the iron maximum are not satisfied by every heat.
Mechanical properties of NiCr23Fe forgings
Specified requirements, solution annealed
These are the values a mill test certificate has to meet at room temperature. They are minimums rather than expected test results.
| Property | Metric | Imperial |
|---|---|---|
| Tensile strength Rm | 550–750 MPa | 80–109 ksi |
| Yield strength Rp0.2, min | 205 MPa | 30 ksi |
| Elongation A₅, min | 30 % | 30 % |
| Hardness, max | 220 HB | 220 HB |
Typical as-delivered values
Solution-annealed NiCr23Fe normally tests well above the minimums. The figures below are representative of hot-finished product and vary with section size, finishing temperature and cooling rate.
| Condition | Tensile strength | Yield strength 0.2% | Elongation in 2 in | Hardness |
|---|---|---|---|---|
| Solution-treated hot-finished rod | 596 MPa / 86,500 psi | 197 MPa / 28,500 psi | 58 % | 114 HB |
| Annealed hot-finished flat | 738 MPa / 107,000 psi | 338 MPa / 49,000 psi | 45 % | 161 HB |
Typical values are for design screening only. The mill test certificate issued with each forging governs acceptance. Elevated-temperature tensile, stress-rupture and impact testing can be added to the order where the design code requires it.
Physical properties of NiCr23Fe
| Property | Metric | Imperial |
|---|---|---|
| Density | 8.11 g/cm³ | 0.293 lb/in³ |
| Melting range | 1360–1411 °C | 2480–2571 °F |
| Modulus of elasticity | 206.8 GPa | 30.0 × 10⁶ psi |
| Specific heat, 20 °C | 448 J/kg·K | 0.107 Btu/lb·°F |
| Thermal conductivity, 20 °C | 11.3 W/m·K | 78 Btu·in/ft²·h·°F |
| Mean expansion, 20–100 °C | 13.75 µm/m·K | 7.6 × 10⁻⁶ in/in·°F |
| Electrical resistivity | 1.19 µΩ·m | 716 Ω·circ mil/ft |
| Magnetic permeability | 1.003 at 200 Oe | essentially non-magnetic |
High electrical resistivity combined with oxidation resistance also puts the grade into electrical resistance heating elements and their forged terminal hardware.
NiCr23Fe compared with Alloy 600, 602 CA and 800HT
These four grades cover similar duty in hot air, combustion gas and carburising atmospheres, and are often substituted for one another on drawings without checking the consequences. The differences that matter are aluminium content, iron content and creep strength.
| Criterion | NiCr23Fe / Alloy 601 | Alloy 600 | Alloy 602 CA | Alloy 800HT |
|---|---|---|---|---|
| UNS / W.Nr. | N06601 / 2.4851 | N06600 / 2.4816 | N06025 / 2.4633 | N08811 / 1.4959 |
| Nickel | 58–63% | 72% min | balance | 30–35% |
| Chromium | 21–25% | 14–17% | 24–26% | 19–23% |
| Aluminium | 1.0–1.7% | not specified | 1.8–2.4% | 0.15–0.60% |
| Practical limit in air | 1200 °C | about 1100 °C | 1200 °C and above | about 982 °C |
| Carburisation resistance | Good | Moderate | Excellent | Moderate |
| Creep strength | Moderate | Moderate | High | High for an iron base |
| Relative cost | Medium | Medium-high | High | Low |
| Typical selection | Cyclic oxidation above 1000 °C at moderate load | Reducing or chloride service, caustics | Extreme temperature with sustained load | Below 982 °C where cost governs |
Selection summary. Alloy 600 for reducing and chloride environments. NiCr23Fe for cyclic oxidation and carburisation above 1000 °C. Alloy 602 CA where NiCr23Fe lacks creep strength. Alloy 800HT where the temperature is low enough for an iron-base grade to be economic.
NiCr23Fe equivalent designations
| System | Designation |
|---|---|
| Werkstoff Nr. (Germany) | 2.4851 |
| DIN / EN name | NiCr23Fe |
| UNS (USA) | N06601 |
| ISO | NiCr23Fe15Al |
| AFNOR (France) | NC23FeA |
| BS (UK) | NA 49 |
| JIS (Japan) | NCF 601 |
| GB (China) | NS313 / GH3608 (nearest) |
| Generic name | Alloy 601 |
| Trade names | Inconel® 601, Nicrofer® 6023 / 6023 H, Pyromet® 601, Sanicro® 61 |
Designations marked "nearest" are close but not identical. Where a design registration or code case is involved, order to the UNS number or the Werkstoff number and confirm equivalence against the mill certificate rather than against a cross-reference table.
Inconel® and Pyromet® are registered trademarks of Special Metals Corporation, Nicrofer® of VDM Metals, Sanicro® of Sandvik. Jiangyin Jiangnan Metal Co., Ltd. is not affiliated with these trademark holders. The marks are used here only to identify equivalent material specifications.
Standards by product form
| Product form | ASTM / ASME | AMS | European |
|---|---|---|---|
| Forgings, rings, discs | Chemistry and bar properties per B166 / SB-166 | AMS 5715 (bar, forgings and rings) | DIN EN 10095, DIN 17742, VdTÜV 471 |
| Rod, bar and wire | B166 / SB-166 | AMS 5715 | DIN EN 10095, DIN 17752, DIN 17753 |
| Plate, sheet and strip | B168 / SB-168 | AMS 5870 | DIN EN 10095, DIN 17750 |
| Seamless pipe and tube | B167, B163 / SB-167, SB-163 | - | DIN 17751 |
| Welding consumables | AWS A5.14 ERNiCrFe-11 | - | EN ISO 18274 |
No ASTM specification is written specifically for Alloy 601 forgings. Forgings are normally ordered to the chemistry of B166 or to AMS 5715, with mechanical acceptance criteria stated on the drawing or purchase order. For pressure-retaining service, confirm code acceptance of N06601 with the design authority before ordering. In most plants the grade is used for furnace and process hardware rather than code-stamped pressure parts.
NiCr23Fe forgings we produce
Jiangyin Jiangnan Metal Co., Ltd. is an open-die forging factory. Each item listed below is forged to the customer's drawing or dimensional sketch. There is no fixed catalogue, no die cost and no minimum piece count, so open-die work suits one-off furnace spares as well as production batches.
Size and weight capability
| Product form | Dimensional range | Unit weight |
|---|---|---|
| Seamless rolled rings | OD 200–3,000 mm, height to 800 mm | 20–8,000 kg |
| Round bars | Ø80–800 mm, length to 6,000 mm | 20–6,000 kg |
| Discs and tube sheets | Ø200–2,500 mm, thickness to 600 mm | 30–10,000 kg |
| Shafts, sleeves, blocks | to 6,000 mm long | to 10,000 kg |
Machining allowance is normally 6–20 mm per surface depending on section size, unless the drawing states otherwise. Finish-machined parts to print are also supplied.
How we make NiCr23Fe forgings
- MeltingNiCr23Fe stock is melted by EAF + VOD, with ESR remelting where the specification or the service calls for improved cleanliness and reduced segregation.
- Heat verificationChemistry is confirmed by spectrometer against DIN EN 10095 or UNS N06601 limits, including the 1.00–1.70% aluminium window, before any material is heated.
- Open-die forgingWorked between 980 °C and 1230 °C on hydraulic presses with a controlled reduction ratio, closing porosity and developing a grain flow that follows the part contour. Rings are ring-rolled seamless. Reheating is used rather than finishing too cold, because NiCr23Fe stiffens sharply below about 1000 °C.
- Solution annealingHeld at 1100–1180 °C and rapidly cooled, passing quickly through 650–870 °C. NiCr23Fe is a solid-solution alloy and is never age hardened.
- Rough or finish machiningTurned, bored, drilled and faced to the drawing, with agreed machining allowance or to final dimensions.
- Non-destructive testingUltrasonic examination to EN 10228-3, SEP 1921, ASTM A388 or the nominated class. Liquid penetrant and dimensional inspection as required.
- Certification and despatchEN 10204 3.1 mill certificate as standard, 3.2 with third-party witness on request. Hard stamped, preserved and packed for sea or air freight.
Where NiCr23Fe forgings are used
| Industry | Components forged in NiCr23Fe |
|---|---|
| Industrial furnaces | Radiant tube components, muffle and retort end rings, flame shields, strand-annealing tube ends, roller ends, forged fixture hardware |
| Heat treatment plant | Baskets, trays and fixtures for annealing, carburising, carbonitriding and nitriding, forged support rings and grids |
| Petrochemical and refining | Catalyst grid supports, reformer and cracking furnace hardware, transfer line components, thermowells, forged nozzles and flanges |
| Power generation and gas turbines | Combustor and exhaust hardware, forged rings and casings for hot-gas paths, superheater hangers |
| Waste incineration | Grate bars and grate shafts, boiler tube shields, ash handling components, forged sleeves and bushings |
| Chemical processing | Nitric acid and ammonia plant hardware, sulfur recovery components, forged tube sheets and shell flanges for heat exchangers |
| Pressure vessels and exchangers | Forged tube sheets, shell flanges, blind covers, girth rings, forged pipe and heavy-wall hollow sections |
| Pumps and valves | Valve bodies, bonnets, seat rings and stems for high-temperature duty, pump shafts and sleeves for hot process fluids |
| Electrical heating | Resistance heating element hardware, forged terminals and support rings |
The requirement is the same in each case: an oxide scale that survives thermal cycling, resistance to carburisation, and room-temperature ductility high enough for machining and welding into an assembly.
Testing, inspection and certification
- Chemical analysis. Spectrometric heat analysis, with product analysis on the finished forging on request.
- Mechanical testing. Room-temperature tensile, yield, elongation and hardness as standard. Elevated-temperature tensile, stress-rupture and impact testing to specification.
- Grain size. Determined per ASTM E112 where the drawing calls for it.
- Ultrasonic testing. EN 10228-3, SEP 1921 class C/D/E, ASTM A388 or customer class.
- Surface NDT. Liquid penetrant examination per ASTM E165 / ASME Section V Article 6.
- Intergranular corrosion. ASTM A262 practice as agreed.
- Certification. EN 10204 3.1 as standard, EN 10204 3.2 witnessed by TÜV, BV, LR, SGS or DNV on request. Full heat traceability and hard stamping on every piece.
Frequently asked questions about NiCr23Fe
What is NiCr23Fe?
NiCr23Fe is the DIN/EN short name for the nickel-chromium-iron alloy with Werkstoff number 2.4851, standardised in DIN EN 10095. It contains 58–63% nickel, 21–25% chromium, 1.0–1.7% aluminium and iron as the balance. The name encodes the chemistry: a nickel base with nominally 23% chromium and iron as the next significant element. It is used where components have to resist oxidation and carburisation in air or combustion gas at temperatures up to 1200 °C.
Is NiCr23Fe the same as Inconel 601 or Alloy 601?
Yes. NiCr23Fe, W.Nr. 2.4851, UNS N06601, ISO NiCr23Fe15Al, AFNOR NC23FeA, BS NA 49, JIS NCF 601 and the generic name Alloy 601 all describe the same material. Inconel® 601 is the trade name of Special Metals Corporation and Nicrofer® 6023 is the VDM Metals name for it. To avoid ambiguity, order to 2.4851 with DIN EN 10095, or to UNS N06601 with ASTM B166.
What is the maximum service temperature of NiCr23Fe?
DIN EN 10095 sets the maximum continuous service temperature in air at 1200 °C (2192 °F), defined by an average scaling rate of no more than 1 g/m²·h. Oxidation resistance is still demonstrated up to roughly 1250 °C for short intermittent excursions, but load-carrying capacity there is effectively nil, so the limit becomes mechanical rather than chemical. Where sustained load is applied above 1100 °C, a creep-strengthened grade such as Alloy 602 CA or Inconel 617 is the better choice.
Why does NiCr23Fe contain aluminium?
The 1.0–1.7% aluminium forms a thin continuous Al₂O₃ layer beneath the chromium oxide scale. Above about 1000 °C, Cr₂O₃ begins to volatilise as CrO₃ and the protective layer thins, whereas Al₂O₃ does not. It also adheres far better through heating and cooling cycles, so the scale does not spall off and expose fresh metal. Aluminium is the main compositional difference between NiCr23Fe and Alloy 600, and it accounts for the longer life of NiCr23Fe in cyclic furnace service.
NiCr23Fe or Alloy 600: which should I specify?
Choose NiCr23Fe (Alloy 601) for cyclic oxidation and carburising atmospheres above about 1000 °C, where the aluminium-bearing scale decides service life. Choose Alloy 600 (2.4816 / N06600) for reducing conditions, chloride-bearing aqueous service, caustics and high-purity water, where its higher nickel content of 72% minimum is worth more than the aluminium. Both resist chloride stress-corrosion cracking, but only NiCr23Fe survives repeated cycling near 1200 °C.
Which heat treatment is correct for NiCr23Fe forgings?
Solution annealing at 1100–1180 °C followed by rapid cooling. NiCr23Fe is a solid-solution alloy and is not precipitation hardened, so no ageing treatment is applied and none would raise its strength usefully. Cooling should pass quickly through 650–870 °C, because slow cooling in that range can precipitate carbides at grain boundaries and reduce ductility. Forgings are supplied in the solution-annealed condition unless the order states otherwise.
Can NiCr23Fe be welded?
Yes. NiCr23Fe is readily welded by GTAW, GMAW and SMAW. The matching filler metal is AWS A5.14 ERNiCrFe-11, and post-weld heat treatment is not normally required for the alloy itself, although the design code may call for it. Keep heat input moderate and interpass temperature low, and clean the weld preparation thoroughly, since the aluminium that gives the alloy its oxidation resistance also forms a tenacious surface oxide.
Is NiCr23Fe magnetic, and how does it machine?
It is essentially non-magnetic, with a relative permeability of about 1.003 at 200 Oe. Machining behaves like other solid-solution nickel alloys. The material work hardens rapidly, so it needs positive rake, rigid setups, slow speeds, heavy positive feed and no dwelling in the cut. Machinability is roughly 15–20% of free-machining carbon steel, which is why most buyers order forgings close to net shape with a defined machining allowance rather than machining down from oversized stock.
What sizes of NiCr23Fe forgings can you supply?
Seamless rolled rings from 200 to 3,000 mm outside diameter, round bars from Ø80 to Ø800 mm, discs and tube sheets to Ø2,500 mm and 600 mm thick, and shafts, sleeves and blocks to 6,000 mm long, with single-piece weights up to 10,000 kg. Open-die forging requires no dies, so prototype and one-off quantities are economic. There is no tooling charge and no minimum order quantity by piece.
Do you supply a material certificate with NiCr23Fe forgings?
Every forging ships with an EN 10204 3.1 mill test certificate as standard, showing heat number, chemical analysis, mechanical test results, heat treatment record and NDT results. EN 10204 3.2 certification witnessed by a third party such as TÜV, BV, LR, SGS or DNV is available on request at the time of order.
How long does a NiCr23Fe forging take to produce?
Lead time depends on whether the grade is in raw stock and on the size of the piece. Simple rings and discs from stock material typically run 25–40 days. Parts requiring a new melt, ESR remelting, heavy machining or third-party witnessed inspection take longer. Send the drawing and we confirm a firm date with the quotation.
Who supplies open-die forged NiCr23Fe parts in China?
Jiangyin Jiangnan Metal Co., Ltd. is an open-die forging factory located at No.1 Chengxiqiao Road, Zhouzhuang Town, Jiangyin City, Jiangsu Province, China. Operating since 2008 and certified to ISO 9001:2015, it forges NiCr23Fe (2.4851 / Alloy 601) together with other nickel alloys, stainless steels, tool steels, alloy steels and carbon steels into seamless rolled rings, flanges, bars, discs, shafts, sleeves, bushings and tube sheets, and exports worldwide. Enquiries: sales@steelforgepieces.com or +86 189 2135 9659.
Data sheet reference
| Document | NiCr23Fe (2.4851 / UNS N06601) open-die forgings, technical data sheet |
|---|---|
| Grade covered | NiCr23Fe, W.Nr. 2.4851, UNS N06601, Alloy 601, ISO NiCr23Fe15Al |
| Standards referenced | DIN EN 10095, DIN 17742, VdTÜV 471, ASTM B166, ASTM B167, ASTM B168, AMS 5715, AWS A5.14, EN 10204, EN 10228-3 |
| Key data | Ni 58–63%, Cr 21–25%, Al 1.0–1.7%, Fe balance. Density 8.11 g/cm³. Melting range 1360–1411 °C. Maximum continuous service in air 1200 °C. Supplied solution annealed 1100–1180 °C. |
| Issued by | Jiangyin Jiangnan Metal Co., Ltd., No.1 Chengxiqiao Road, Zhouzhuang Town, Jiangyin City, Jiangsu Province, China |
| Revision | 23 August 2026 |
| Reference as | Jiangyin Jiangnan Metal Co., Ltd. NiCr23Fe (W.Nr. 2.4851 / Alloy 601 / UNS N06601) open-die forgings, technical data sheet. https://www.steelforgepieces.com/Nickel-Alloy/NiCr23Fe.html |
Request a quotation for NiCr23Fe forgings
Send a drawing, a sketch, or the dimensions and quantity. Open-die forgings in NiCr23Fe are quoted with no tooling charge and no piece minimum, normally within 24 hours.
Useful details if available: grade and standard (NiCr23Fe / 2.4851 / UNS N06601, DIN EN 10095 or ASTM B166), product form, dimensions with machining allowance, quantity, delivery condition, NDT class, certificate type and required delivery date.
| Company | Jiangyin Jiangnan Metal Co., Ltd. |
|---|---|
| Business | Open-die forging factory, established 2008 |
| Address | No.1 Chengxiqiao Road, Zhouzhuang Town, Jiangyin City, Jiangsu Province, China |
| Telephone / WhatsApp | +86 189 2135 9659 |
| sales@steelforgepieces.com | |
| Website | www.steelforgepieces.com |
| Quality system | ISO 9001:2015, EN 10204 3.1 / 3.2 certification |