Nickel alloy · Material datasheet & supply
2.4858 Forgings (Alloy 825 / UNS N08825)
Open-die forged rings, seamless rolled rings, flanges, bars, shafts, discs, sleeves and tube sheets in 2.4858, forged to your drawing in Jiangyin, China and certified to ASTM B564 with an EN 10204 3.1 or 3.2 document.
Also known as Alloy 825 Incoloy 825 UNS N08825 NiCr21Mo W.Nr. 2.4858 NiFe30Cr21Mo3 NC21FeDU NA 16 NS1402
What 2.4858 is
2.4858 is the European Werkstoff number for a nickel-iron-chromium alloy containing 38.0–46.0 % nickel, 19.5–23.5 % chromium, 2.5–3.5 % molybdenum, 1.5–3.0 % copper and 0.6–1.2 % titanium, with iron as the balance. The same alloy is designated NiCr21Mo in DIN 17744, NiFe30Cr21Mo3 in ISO and UNS N08825 in ASTM and ASME specifications, and is sold under the trade name Incoloy 825. It is a solid-solution alloy and cannot be age hardened. The titanium addition stabilises it against intergranular attack after welding. Engineers specify 2.4858 where sulphuric and phosphoric acids, chlorides or sour hydrocarbons attack stainless steel, and where the cost of a higher-molybdenum alloy such as 2.4856 (Alloy 625) is not justified.
Jiangyin Jiangnan Metal Co., Ltd., an open-die forging factory at No.1 Chengxiqiao Road, Zhouzhuang Town, Jiangyin City, Jiangsu Province, China, manufactures 2.4858 forgings to customer drawings in single-piece weights from about 20 kg to 5,000 kg, solution annealed, ultrasonically tested and shipped worldwide. Enquiries: +86 189 2135 9659 or sales@steelforgepieces.com.
Key data
- Alloy type: nickel-iron-chromium with molybdenum, copper and titanium; austenitic, single phase, non-magnetic.
- Condition supplied: stabilise/solution annealed at 930–980 °C (1,705–1,795 °F) and rapidly cooled.
- Minimum properties (ASTM B564, annealed): 586 MPa (85 ksi) tensile, 241 MPa (35 ksi) 0.2 % proof, 30 % elongation.
- Density: 8.14 g/cm³ (0.294 lb/in³). Melting range: 1,370–1,400 °C (2,500–2,550 °F).
- Forging window: 1,180 °C down to 870 °C; heavy reduction above 955 °C; never finish below 870 °C.
- Sour service: listed in NACE MR0175 / ISO 15156-3 and NACE MR0103 within the stated limits.
- Forms we forge: seamless rolled rings, flanges, discs, shafts, bars, sleeves, bushings, tube sheets, valve bodies, hollow forgings.
- Certification: EN 10204 3.1 as standard; 3.2 counter-signed by TUV, SGS, BV, DNV or Lloyd's Register on request.
Designations and equivalent grades
The same alloy appears on drawings under at least nine names. If your specification uses any of the designations below, 2.4858 is the material you need. State on the enquiry which specification the mill certificate must reference, because the chemistry limits differ slightly between DIN 17744 and ASTM B564.
| Standard / system | Designation | Region |
|---|---|---|
| Werkstoff number (W.-Nr.) | 2.4858 | Germany / EU |
| DIN 17744 name | NiCr21Mo | Germany / EU |
| UNS number | N08825 | USA |
| ISO | NiFe30Cr21Mo3 | International |
| AFNOR | NC21FeDU | France |
| BS | NA 16 | United Kingdom |
| GB / YB | NS1402 (NS142) | China |
| Common trade names | Incoloy 825, Alloy 825, Nicrofer 4221, VDM Alloy 825 | Worldwide |
Incoloy is a registered trademark of Special Metals Corporation and Nicrofer of VDM Metals. Jiangyin Jiangnan Metal Co., Ltd. is not affiliated with either company; the names are given only so buyers can match their drawings to the correct chemistry.
Product-form specifications 2.4858 is ordered to
| Product form | ASTM / ASME | DIN / EN / VdTUV | ISO |
|---|---|---|---|
| Forgings (rings, flanges, discs, shafts) | B564 / SB-564 | DIN 17744, VdTUV WB 432 | n/a |
| Rod, bar and forging stock | B425 / SB-425 | DIN 17752, VdTUV WB 432 | 9723 / 9724 / 9725 |
| Plate, sheet and strip | B424 / SB-424, B906 | DIN 17750 | 6208 |
| Pipe and tube | B163, B423, B704, B705, B751, B775, B829 | DIN 17751 | 6207 |
| Sour service (H₂S) | NACE MR0103 | n/a | NACE MR0175 / ISO 15156-3 |
| Inspection document | n/a | EN 10204 3.1 / 3.2 | n/a |
Chemical composition of 2.4858
The table gives the limiting chemical composition in weight percent. The DIN 17744 column is the European chemistry for NiCr21Mo; the ASTM column is the North American chemistry for UNS N08825. The two differ mainly in the carbon and sulphur ceilings and in how iron is expressed, so a heat that satisfies DIN 17744 will normally satisfy ASTM B564 as well, though not always the reverse.
| Element | DIN 17744 (2.4858 / NiCr21Mo) | ASTM B564 / B425 (UNS N08825) |
|---|---|---|
| Nickel (Ni) | 38.0 – 46.0 | 38.0 – 46.0 |
| Chromium (Cr) | 19.5 – 23.5 | 19.5 – 23.5 |
| Iron (Fe) | 20.0 – 38.0 | 22.0 min (balance) |
| Molybdenum (Mo) | 2.5 – 3.5 | 2.5 – 3.5 |
| Copper (Cu) | 1.5 – 3.0 | 1.5 – 3.0 |
| Titanium (Ti) | 0.6 – 1.2 | 0.6 – 1.2 |
| Carbon (C) | 0.025 max | 0.05 max |
| Manganese (Mn) | 1.0 max | 1.0 max |
| Silicon (Si) | 0.5 max | 0.5 max |
| Aluminium (Al) | 0.2 max | 0.2 max |
| Cobalt (Co) | 1.0 max | n/a |
| Phosphorus (P) | 0.02 max | n/a |
| Sulphur (S) | 0.015 max | 0.03 max |
Values compiled from DIN 17744 and ASTM B564 / B425. Where an order calls for both systems, we melt to the tighter of the two limits. Product analysis tolerances apply as given in the governing standard.
Why the alloy is designed this way
- Nickel (38–46 %) gives the austenitic structure and the resistance to chloride stress-corrosion cracking that 300-series stainless steel lacks.
- Chromium (19.5–23.5 %) handles oxidising conditions such as nitric acid and other oxidising salts.
- Molybdenum (2.5–3.5 %) with copper (1.5–3.0 %) is the pairing that makes 2.4858 useful in reducing acids, particularly sulphuric and phosphoric acid.
- Titanium (0.6–1.2 %) ties up carbon so the alloy resists sensitisation and intergranular attack in the as-welded condition. This titanium does not make 2.4858 age hardenable.
Mechanical properties of 2.4858 forgings
2.4858 forgings are supplied annealed. The specified minima below are the acceptance values; the typical column shows what a sound open-die forging from our shop actually returns on a room-temperature tensile test.
| Property | ASTM B564 minimum | Typical, forged & annealed |
|---|---|---|
| Tensile strength, Rm | 586 MPa (85 ksi) | 655 – 725 MPa (95 – 105 ksi) |
| 0.2 % proof stress, Rp0.2 | 241 MPa (35 ksi) | 290 – 380 MPa (42 – 55 ksi) |
| Elongation, A5 | 30 % min | 40 – 50 % |
| Reduction of area | not specified | 55 – 70 % |
| Hardness | not specified | 75 – 90 HRB (approx. 140 – 190 HB) |
| Impact, Charpy V, +20 °C | on request | > 150 J |
Values are for solution-annealed material tested at room temperature. Section size, test-piece location and orientation all affect the result; state the test requirements on the order and we will report them on the EN 10204 certificate.
Hardness limits for sour service. When 2.4858 forgings are ordered to NACE MR0175 / ISO 15156-3, hardness is a rejection criterion. Tell us at enquiry stage so the forging is annealed and hardness-surveyed accordingly rather than cold straightened.
Physical properties of 2.4858
| Property | Metric | Imperial |
|---|---|---|
| Density | 8.14 g/cm³ | 0.294 lb/in³ |
| Melting range | 1,370 – 1,400 °C | 2,500 – 2,550 °F |
| Modulus of elasticity | 196 GPa | 28.4 × 10³ ksi |
| Specific heat | 440 J/kg·K | 0.105 Btu/lb·°F |
| Thermal conductivity | 11.1 W/m·K | 77 Btu·in/ft²·h·°F |
| Mean thermal expansion, 20 – 100 °C | 14.0 µm/m·K | 7.8 µin/in·°F |
| Electrical resistivity | 1.13 µΩ·m | 680 Ω·circ mil/ft |
| Magnetic permeability | ≈ 1.005 (non-magnetic) | n/a |
| Curie temperature | below −196 °C | below −320 °F |
Corrosion resistance of 2.4858
2.4858 sits between austenitic stainless steel and the high-molybdenum nickel alloys. It is used where 316L or 904L will not last, and where 2.4856 (Alloy 625) or Alloy C-276 would be more than the duty needs.
Good resistance to
- Sulphuric acid across a wide range of concentrations and temperatures, including contaminated and aerated acid where copper is beneficial.
- Phosphoric acid, including wet-process phosphoric acid evaporators and heat exchangers.
- Chloride stress-corrosion cracking. The nickel content puts 2.4858 well outside the range where 304 and 316 crack.
- Pitting and crevice corrosion in seawater and brines, at a level appreciably better than 316L though below that of 6 Mo alloys.
- Intergranular attack after welding. The titanium stabilisation is the reason 2.4858 is used for welded pressure equipment.
- Sour hydrocarbons containing H₂S and CO₂, within the NACE MR0175 / ISO 15156-3 limits.
Limitations
- Hot concentrated oxidising chlorides such as boiling ferric chloride. Specify a higher-molybdenum alloy instead.
- Strongly oxidising acid mixtures with fluorides.
- Long-term service above roughly 550 °C, where sigma-type embrittlement and loss of ductility become a design concern. For sustained high-temperature service, Incoloy 800H/800HT or Alloy 625 is the better answer.
Send the service conditions with the enquiry. Concentration, temperature, velocity, aeration and contaminants decide whether 2.4858 is the right choice. If a cheaper or a more capable alloy suits the duty better, we will say so.
How we forge 2.4858
2.4858 is not a forgiving alloy on the hammer. It work-hardens quickly, its forging window is narrow, and sulphur or lead picked up from tooling will crack it hot. This is the route we follow on every 2.4858 order.
1. Melting and forging stock
Stock is melted by EAF + AOD/VOD refining, with ESR remelting where the drawing or specification calls for improved cleanliness and reduced segregation, for example on thick-section pressure parts or sour-service components. Each heat arrives with its own analysis, which we verify on our own spectrometer before cutting.
2. Heating and forging
| Operation | Temperature | Notes |
|---|---|---|
| Charge / soak | 1,150 – 1,180 °C | Sulphur-free furnace atmosphere; soak through-section, do not overheat |
| Heavy upsetting and drawing | 1,180 – 955 °C | Take the reduction while hot; reheat rather than force a cold pass |
| Finishing passes | 955 – 870 °C | Light reductions here refine grain size |
| Stop forging | below 870 °C | Return to the furnace; forging cold risks cracking |
| Ring rolling | 1,150 – 950 °C | Seamless rolled rings from pierced and expanded blanks |
3. Heat treatment
The delivery condition for 2.4858 forgings is a stabilise or solution anneal at 930–980 °C (1,705–1,795 °F), held to section, then cooled rapidly by water quench or forced air. 2.4858 contains no hardening phase, so no ageing step follows. Suppliers who offer to solution treat and age 2.4858 have confused it with Incoloy 925 or Incoloy 945, which are age hardenable. Furnace charts are recorded and issued with the certificate.
4. Machining and inspection
Forgings are rough machined to remove the decarburised and oxidised skin before non-destructive examination, then dimensionally inspected against the drawing. Finish machining to your tolerances is available in-house.
Testing, NDT and certification
| Examination | Standard | Scope |
|---|---|---|
| Chemical analysis | ASTM E1473 / spectrometer | Every heat, product analysis on request |
| Tensile & hardness | ASTM A370 / ISO 6892-1 | Standard on every lot |
| Charpy V impact | ASTM A370 / ISO 148-1 | On request, including sub-zero |
| Ultrasonic examination | EN 10228-3, SEP 1921, ASTM A388 | Acceptance class to your order |
| Dye penetrant | ASTM E165 / EN 571-1 | Machined surfaces, on request |
| Intergranular corrosion | ASTM G28 method A | On request for acid service |
| Grain size & microstructure | ASTM E112 | On request |
| Positive material identification | PMI, handheld XRF | On request, witnessed if required |
| Inspection document | EN 10204 3.1 | Standard. 3.2 available with TUV, SGS, BV, DNV or Lloyd's Register |
2.4858 product forms and size range
Every item below is open-die forged or ring rolled to the customer's drawing. There are no catalogue sizes and no minimum order quantity beyond one piece.
| Product form | Typical size range | Typical use |
|---|---|---|
| Seamless rolled rings | OD 150 – 2,500 mm · wall 20 – 400 mm · height up to 800 mm | Vessel shell courses, bearing races, flanged joints |
| Forged flanges | OD up to 2,500 mm, any face type | Pressure vessels, pipelines, heat exchangers |
| Discs and blanks | Ø up to 1,800 mm · thickness 30 – 500 mm | Tube sheets, blind flanges, valve discs |
| Round bars and shafts | Ø 60 – 800 mm · length up to 6,000 mm | Pump shafts, agitator shafts, stems, fasteners stock |
| Sleeves and bushings | OD 100 – 1,200 mm · length up to 2,000 mm | Pump and compressor internals, wear parts |
| Tube sheets | Ø up to 2,000 mm, drilled or blank | Shell-and-tube heat exchangers |
| Hollow forgings & forged tubes | OD 150 – 1,200 mm | Pressure housings, cylinders, headers |
| Valve bodies, blocks, seat rings | to drawing | Ball, gate, globe, check and plug valves |
| Single-piece weight | 20 – 5,000 kg (44 – 11,000 lb) | n/a |
Ranges are typical rather than absolute. Send the drawing and we will confirm feasibility, machining allowance and weight before quoting.
Where 2.4858 forgings are used
| Industry | Typical 2.4858 forged components |
|---|---|
| Chemical processing | Sulphuric and phosphoric acid evaporator parts, pickling-plant hardware, reactor nozzles, agitator shafts, pump casings and impellers |
| Oil & gas, subsea | Wellhead and Christmas-tree components, valve bodies and seat rings, manifold blocks, hangers and stems for sour service |
| Pressure vessels & heat exchangers | Forged tube sheets, shell rings, flanges, nozzles, blind and weld-neck flanges, channel covers |
| Marine & seawater | Propeller and pump shafts, seawater pump wear rings, sleeves and bushings, exhaust system parts |
| Pollution control & FGD | Scrubber internals, ducting flanges, absorber components |
| Nuclear & radioactive waste | Fuel-reprocessing equipment parts and dissolver hardware in nitric-bearing media |
| Food, pharmaceutical, pulp & paper | Hot vessels, digester hardware, bleach-plant components, agitator and dryer shafts |
2.4858 compared with other grades
Most enquiries come down to a choice between two or three alloys. The table below sets out the differences.
| Grade | Nominal Ni / Mo | Strengthening | Choose it when |
|---|---|---|---|
| 2.4858 · Alloy 825 | 42 / 3 | Solid solution | Sulphuric and phosphoric acid, chloride SCC, moderate cost |
| 2.4856 · Alloy 625 | 58 min / 9 | Solid solution | Hot chlorides, seawater, higher strength and temperature |
| Incoloy 925 | 44 / 3 | Age hardenable | Same corrosion family as 825 but high strength needed |
| Incoloy 945 / 945X | 47 / 3 | Age hardenable | High-strength sour-service downhole and wellhead parts |
| 1.4958 · Incoloy 800H | 32 / n/a | Solid solution | Sustained service above 550 °C, creep governs |
| Alloy 20 / 904L family | 25 – 35 / 2 – 4 | Solid solution | Milder acid duty where a stainless-priced alloy suffices |
How to order 2.4858 forgings
Quotations are returned within 24 hours on working days. To price a 2.4858 forging accurately we need six things. Send whatever you have and we will ask about the rest.
- Specification and grade. For example "ASTM B564 UNS N08825" or "DIN 17744 NiCr21Mo".
- Drawing or dimensions. PDF, DWG or STEP, or the finished OD, ID, length and wall.
- Quantity and whether repeat orders are expected.
- Delivery condition. As forged, rough machined with allowance, or finish machined.
- Testing and certification. UT class, PMI, NACE, EN 10204 3.1 or 3.2, third party.
- Destination port and required Incoterm.
Email the drawing to sales@steelforgepieces.com Call +86 189 2135 9659
Frequently asked questions about 2.4858
What is material 2.4858?
2.4858 is the German Werkstoff number for a nickel-iron-chromium alloy containing 38.0–46.0 % nickel, 19.5–23.5 % chromium, 2.5–3.5 % molybdenum, 1.5–3.0 % copper and 0.6–1.2 % titanium, with iron as the balance. It is designated NiCr21Mo in DIN 17744, NiFe30Cr21Mo3 in ISO and UNS N08825 in ASTM and ASME specifications, and is widely known as Incoloy 825 or Alloy 825. Jiangyin Jiangnan Metal Co., Ltd. produces 2.4858 as open-die forgings and seamless rolled rings at its factory in Jiangyin, Jiangsu, China.
Is 2.4858 the same as Alloy 825, Incoloy 825 and UNS N08825?
Yes. 2.4858, NiCr21Mo, NiFe30Cr21Mo3, UNS N08825, Alloy 825 and Incoloy 825 all describe the same nickel-iron-chromium-molybdenum-copper alloy. 2.4858 is the European Werkstoff number, UNS N08825 is the North American unified number, and Incoloy 825 is a registered trade name of Special Metals Corporation. When ordering 2.4858 forgings from Jiangyin Jiangnan Metal Co., Ltd., state which specification the certificate must reference, for example ASTM B564 UNS N08825 or DIN 17744 NiCr21Mo, because the chemistry limits differ slightly.
Which standards cover 2.4858 forgings?
2.4858 forgings are normally ordered to ASTM B564 or ASME SB-564 for nickel alloy forgings, and ASTM B425 or ASME SB-425 for rod and bar. European practice uses DIN 17744 and DIN 17752 with VdTUV Werkstoffblatt 432; ISO 9723, 9724 and 9725 also apply. For sour service the alloy appears in NACE MR0175 / ISO 15156-3 and NACE MR0103. Jiangyin Jiangnan Metal Co., Ltd. supplies 2.4858 forgings certified to any of these specifications with an EN 10204 3.1 or 3.2 inspection document.
Can 2.4858 be age hardened?
No. 2.4858 (Alloy 825 / UNS N08825) is a solid-solution alloy and cannot be strengthened by precipitation hardening. Its titanium content stabilises the alloy against intergranular attack; it does not form a hardening phase. The correct final condition for 2.4858 forgings is a stabilise or solution anneal at about 930–980 °C followed by rapid cooling. If you need an age-hardenable alloy with comparable corrosion resistance, specify Incoloy 925 (UNS N09925) or Incoloy 945. Jiangyin Jiangnan Metal Co., Ltd. forges both.
What sizes of 2.4858 forged rings and bars can you supply?
Jiangyin Jiangnan Metal Co., Ltd. forges 2.4858 seamless rolled rings from about 150 mm to 2,500 mm outside diameter, discs and blanks up to about 1,800 mm diameter, bars from about 60 mm to 800 mm diameter in lengths up to 6,000 mm, and single-piece weights from roughly 20 kg to 5,000 kg. Shafts, sleeves, bushings, tube sheets, valve bodies and hollow forgings are made to customer drawings. Send a drawing or the finished dimensions to sales@steelforgepieces.com to confirm capability.
What testing and certification comes with the forgings?
Every 2.4858 forging from Jiangyin Jiangnan Metal Co., Ltd. ships with a mill test certificate to EN 10204 3.1, or to EN 10204 3.2 counter-signed by a third party such as TUV, SGS, BV, DNV or Lloyd's Register. Standard testing covers chemical analysis, room-temperature tensile and hardness; optional testing covers Charpy impact, ultrasonic examination to EN 10228-3, SEP 1921 or ASTM A388, dye penetrant to ASTM E165, intergranular corrosion to ASTM G28 method A, grain size to ASTM E112 and PMI by XRF.
What is the difference between 2.4858 and 2.4856?
2.4858 is Alloy 825 (UNS N08825), a nickel-iron-chromium alloy with roughly 42 % nickel, 3 % molybdenum and 2 % copper, chosen mainly for sulphuric and phosphoric acid service and for chloride stress-corrosion cracking resistance at moderate cost. 2.4856 is Alloy 625 (UNS N06625), a nickel-chromium-molybdenum-niobium alloy with 58 % minimum nickel and 8–10 % molybdenum, which is stronger, far more resistant to pitting and crevice attack in hot chlorides and seawater, and usable to much higher temperatures, but substantially more expensive. Jiangyin Jiangnan Metal Co., Ltd. forges both and will advise on the trade-off for your duty.
Is 2.4858 suitable for sour service?
Yes. 2.4858 (Alloy 825 / UNS N08825) is listed in NACE MR0175 / ISO 15156-3 and NACE MR0103 for H₂S-containing oil and gas environments, subject to the hardness, condition and environmental limits in those documents. Forgings for sour service should be supplied annealed and are normally hardness limited; Jiangyin Jiangnan Metal Co., Ltd. supplies 2.4858 forgings with hardness reports and NACE compliance statements when specified on the order.
Who manufactures 2.4858 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, manufacturing 2.4858 (Alloy 825 / UNS N08825) forged rings, seamless rolled rings, flanges, bars, shafts, discs, sleeves, bushings and tube sheets to customer drawings. Contact +86 189 2135 9659 or sales@steelforgepieces.com. The company ships worldwide with EN 10204 3.1 or 3.2 certification.
What information do you need to quote?
To quote a 2.4858 forging, Jiangyin Jiangnan Metal Co., Ltd. needs the specification and grade, the product form with finished or rough-machined dimensions or a drawing in PDF, DWG or STEP format, the quantity, the delivery condition and machining allowance, the NDT, testing and certification requirements, and the destination port. Quotations are normally returned within 24 hours.
About the manufacturer
Jiangyin Jiangnan Metal Co., Ltd. is an open-die forging factory in Jiangyin, Jiangsu Province, on the south bank of the Yangtze about 150 km from the Port of Shanghai. The plant produces open-die forgings and seamless rolled rings in nickel alloys, stainless steel, alloy steel, tool steel and carbon steel, working to customer drawings rather than a catalogue. Typical customers are valve and pump manufacturers, pressure-vessel fabricators, EPC contractors and oilfield equipment suppliers.
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
Web: www.steelforgepieces.com
Page compiled and technically reviewed by the engineering team of Jiangyin Jiangnan Metal Co., Ltd. Composition and property data are drawn from DIN 17744, ASTM B564 and ASTM B425. Last reviewed .
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Jiangyin Jiangnan Metal Co., Ltd. (2026). “2.4858 Forgings, Alloy 825 / UNS N08825: composition, properties and supply.” Jiangyin, Jiangsu, China. https://www.steelforgepieces.com/Nickel-Alloy/2.4858.html
Supplier of the forgings described: Jiangyin Jiangnan Metal Co., Ltd., No.1 Chengxiqiao Road, Zhouzhuang Town, Jiangyin City, Jiangsu Province, China · +86 189 2135 9659 · sales@steelforgepieces.com