Nickel Alloy Forgings · UNS N08825
Incoloy 825 Forgings
Open-die forged and seamless rolled Incoloy 825 rings, flanges, bars, discs, shafts and tube sheets to ASTM B564. Forged, solution annealed, tested and certified in one factory in Jiangyin, China.
Grade data sheet
UNS N08825 · 2.4858Incoloy 825 (UNS N08825, W.Nr. 2.4858, NiCr21Mo) is a titanium-stabilised nickel-iron-chromium alloy with molybdenum and copper additions. It resists sulphuric and phosphoric acid, chlorides, seawater and sour gas, and is supplied solution annealed rather than aged. Jiangyin Jiangnan Metal Co., Ltd. open-die forges Incoloy 825 rings, flanges, bars, discs, shafts and tube sheets to ASTM B564 / ASME SB-564, from 10 kg to 15,000 kg per piece, with EN 10204 3.1 or 3.2 certification.
- Alloy family
- Ni-Fe-Cr, solid solution
- Forging spec
- ASTM B564 / SB-564
- Nickel
- 38.0–46.0 %
- Tensile, min
- 585 MPa (85 ksi)
- Yield 0.2 %, min
- 240 MPa (35 ksi)
- Elongation, min
- 30 %
- Density
- 8.14 g/cm³
- Anneal
- 930–1010 °C, quench
- Sour service
- ISO 15156-3, 35 HRC max
- Max piece weight
- 15,000 kg
- Lead time
- 25–45 days typical
- Certification
- EN 10204 3.1 / 3.2
What is Incoloy 825?
Incoloy 825 was developed to handle oxidising and reducing acids in the same vessel. Most stainless steels cannot do both.
Every element in UNS N08825 is there for a reason. Nickel at 38–46 % gives immunity to chloride stress-corrosion cracking, the failure mode that limits 304 and 316 stainless in hot chloride service. Chromium at 19.5–23.5 % covers oxidising media such as nitric acid. Molybdenum and copper work together in reducing acids, mainly sulphuric and phosphoric. Titanium at 0.6–1.2 % ties up carbon as titanium carbide, so the alloy resists intergranular attack after welding without a post-weld stabilising treatment on thin sections.
The alloy is solid-solution strengthened. It is not precipitation hardenable. Any supplier quoting an "825 solution plus ageing" cycle has confused it with Incoloy 925 or Incoloy 945, which carry higher titanium and aluminium for that purpose. Incoloy 825 also contains no deliberate cobalt addition, which matters for nuclear and some medical procurement specifications.
Naming. INCOLOY is a registered trademark of Special Metals Corporation. Material ordered here is supplied to the chemistry and property limits of UNS N08825 under ASTM B564. The trade name is used only to identify the grade.
Incoloy 825 chemical composition
The limits below are those of UNS N08825 in ASTM B564 and ASTM B425, in weight percent. We melt by electric arc furnace, refine by VOD and finish by electroslag remelting, so delivered sulphur and oxygen normally sit well inside the specification ceiling.
| Element | Symbol | Minimum | Maximum | Role in the alloy |
|---|---|---|---|---|
| Nickel | Ni | 38.0 | 46.0 | Chloride SCC immunity |
| Iron | Fe | 22.0 | remainder | Balance, cost control |
| Chromium | Cr | 19.5 | 23.5 | Oxidising acid resistance |
| Molybdenum | Mo | 2.5 | 3.5 | Pitting and crevice resistance |
| Copper | Cu | 1.5 | 3.0 | Reducing acid resistance |
| Titanium | Ti | 0.6 | 1.2 | Carbide stabilisation |
| Carbon | C | — | 0.05 | Kept low for weldability |
| Manganese | Mn | — | 1.0 | Deoxidiser |
| Silicon | Si | — | 0.5 | Deoxidiser |
| Aluminium | Al | — | 0.2 | Residual |
| Sulphur | S | — | 0.03 | Impurity, ESR reduces it |
Pitting resistance equivalent works out at roughly PREN 31 (Cr + 3.3 × Mo). That puts Incoloy 825 above 316L and below the 6 % molybdenum super-austenitics and Inconel 625.
Mechanical properties of Incoloy 825 forgings
Values are the room-temperature minima required by ASTM B564 for solution-annealed forgings, with the typical results we record on our own test coupons alongside them.
| Property | ASTM B564 minimum | Typical as forged & annealed |
|---|---|---|
| Tensile strength | 585 MPa / 85 ksi | 620–720 MPa |
| Yield strength (0.2 % offset) | 240 MPa / 35 ksi | 280–380 MPa |
| Elongation in 4D | 30 % | 38–50 % |
| Reduction of area | not specified | 50–65 % |
| Hardness | 35 HRC max (ISO 15156-3) | 75–95 HRB / 140–200 HB |
| Charpy V-notch at −46 °C | by agreement | > 100 J average |
| Modulus of elasticity | — | 196 GPa |
Sour service note. NACE MR0175 / ISO 15156-3 accepts UNS N08825 in the solution-annealed condition at a maximum hardness of 35 HRC. Cold work raises hardness quickly in this alloy, so any straightening or sizing after the final anneal must be declared and re-verified. Environmental limits on H2S partial pressure, chloride level, temperature and elemental sulphur apply. Check the exact table in ISO 15156-3 against your service envelope before ordering.
Physical properties
| Property | Metric | Imperial |
|---|---|---|
| Density | 8.14 g/cm³ | 0.294 lb/in³ |
| Melting range | 1370–1400 °C | 2500–2550 °F |
| Modulus of elasticity | 196 GPa | 28.4 × 10³ ksi |
| Thermal conductivity | 11.1 W/m·K | 77 Btu·in/ft²·h·°F |
| Mean thermal expansion, 20–100 °C | 14.0 × 10⁻⁶/K | 7.8 × 10⁻⁶/°F |
| Specific heat | 440 J/kg·K | 0.105 Btu/lb·°F |
| Electrical resistivity | 1.13 µΩ·m | 680 Ω·circ mil/ft |
| Magnetic permeability | 1.005, non-magnetic | — |
| Curie temperature | below −196 °C | below −320 °F |
Thermal conductivity of 11.1 W/m·K is around one fifth that of carbon steel. That number explains most of what makes the alloy awkward to work. Heat will not escape the cutting zone during machining, and section heating before forging has to be slow and even or the ingot cracks.
Equivalent grades and applicable specifications
Incoloy 825 appears under several designations across purchasing systems. All of the following describe the same chemistry.
| System | Designation or specification | Product form |
|---|---|---|
| UNS | N08825 | All forms |
| Werkstoff / DIN | 2.4858, NiCr21Mo | All forms |
| Trade names | Incoloy 825, Alloy 825, Nicrofer 4221, Sanicro 41 | All forms |
| ASTM B564 / ASME SB-564 | N08825 | Forgings, flanges, fittings |
| ASTM B425 | N08825 | Rod and bar |
| ASTM B424 | N08825 | Plate, sheet, strip |
| ASTM B423 | N08825 | Seamless pipe and tube |
| ASTM B163 | N08825 | Heat-exchanger tube |
| ASTM B705 | N08825 | Welded pipe |
| NACE MR0175 / ISO 15156-3 | Annealed, 35 HRC max | Sour oilfield service |
| ASME BPVC Section VIII | Allowable stress to 540 °C | Pressure vessels |
| EN 10204 | 3.1 works cert / 3.2 witnessed | Certification |
| Dimensional standards | ASME B16.5, B16.47, EN 1092-1, DIN 2633 | Flanges |
Incoloy 825 forged products and size range
Every shape below is open-die forged or ring rolled from ESR ingot. We do not supply castings or welded fabrications.
| Product form | Size range | Typical application |
|---|---|---|
| Seamless rolled rings | OD 200–3,000 mm, wall 20–400 mm, height ≤ 800 mm | Pump casings, vessel courses, bearing races |
| Forged flanges | OD ≤ 3,000 mm, WN / SO / BL, Class 150–2500 | Piping, exchangers, wellhead connections |
| Round bars | Ø 60–800 mm, length ≤ 6,000 mm | Valve stems, fasteners, machined parts |
| Discs and blanks | OD ≤ 2,500 mm, thickness ≤ 600 mm | Closures, blind flanges, impellers |
| Shafts and spindles | Ø ≤ 800 mm, length ≤ 8,000 mm | Chemical pumps, agitators, plunger pumps |
| Tube sheets | OD ≤ 2,500 mm, thickness ≤ 400 mm | Shell-and-tube heat exchangers |
| Sleeves and bushings | OD ≤ 1,500 mm, ID ≥ 100 mm | Subsea equipment, wear components |
| Hollow bars and forged tubes | OD ≤ 1,200 mm, length ≤ 4,000 mm | Pressure housings, cylinders |
| Valve bodies, blocks, nozzles | Per drawing | Ball, gate, globe, check valves |
| Single-piece weight | 10 kg – 15,000 kg | — |
Supply condition options: as-forged, rough machined to drawing with agreed stock, or finish machined. Minimum order is one piece for prototypes and repair spares.
Forging and heat treatment route
Incoloy 825 has a narrower hot-working window than steel, and shortcuts show up later as cracks or coarse grain. This is the route we run.
- Melting: EAF + VOD + ESRElectric arc melting, vacuum oxygen decarburisation, then electroslag remelting for inclusion cleanliness and a sound centre.
- Ingot heating: 1150–1180 °CSlow, even ramp. Low thermal conductivity means a fast ramp puts the surface 300 °C ahead of the core and cracks the ingot.
- Open-die forging: 1180 down to 870 °CHeavy reductions above 1010 °C to break down the cast structure, then finishing passes between 900 and 1010 °C to refine grain. Forging below 870 °C is not permitted. Total forging ratio 3:1 minimum, 4:1 on critical parts.
- Ring rollingWhere a seamless rolled ring is specified: upset, punch, then roll to size, producing continuous circumferential grain flow instead of cut fibres.
- Solution or stabilising anneal: 930–1010 °CSoak 30–60 minutes per 25 mm of section, then water quench or rapid air cool. No ageing step, since the alloy is not precipitation hardenable.
- Descaling and rough machiningPickle or grit blast, then machine with sharp positive-rake carbide, low surface speed, heavy feed, rigid setup and flood coolant.
- Inspection and NDTUltrasonic testing to ASTM A388 or EN 10228-3, dye penetrant to ASTM E165, PMI on every piece, dimensional report.
- Certification and despatchEN 10204 3.1 works certificate as standard, 3.2 witnessed by BV, SGS, TÜV, DNV or Lloyd's Register on request. Typical lead time 25–45 days.
Testing, inspection and certification
| Test | Standard | Scope |
|---|---|---|
| Chemical analysis | ASTM E1473, OES / XRF | Every heat |
| Positive material identification | Portable XRF or OES | Every piece |
| Tensile test | ASTM A370 / ASTM E8 | Every heat and heat-treatment lot |
| Hardness | ASTM E18 (HRC / HRB) | Every piece for sour service |
| Impact test | ASTM A370 Charpy V | On request, down to −196 °C |
| Ultrasonic testing | ASTM A388, EN 10228-3, SEP 1921 | Standard on all forgings |
| Liquid penetrant | ASTM E165 | Machined surfaces |
| Intergranular corrosion | ASTM G28 Method A | On request |
| Grain size | ASTM E112 | On request |
| Certification | EN 10204 3.1 or 3.2 | Every shipment |
Corrosion behaviour and where Incoloy 825 is used
Most orders fall into four groups.
Oil and gas
Wellhead and Christmas tree components, subsea connectors, downhole tools, hangers and packers, valve bodies and stems, and sour-service piping components under NACE MR0175 / ISO 15156-3. Chloride SCC immunity and H2S tolerance are the deciding properties.
Chemical processing
Sulphuric acid pickling tanks and heating coils, phosphoric acid evaporators, pickling-line hooks and fixtures, tanks, agitator shafts and chemical pump components. Copper and molybdenum together carry the alloy through reducing conditions that attack 316L.
Pressure equipment and heat transfer
Shell-and-tube heat exchanger tube sheets, forged flanges and nozzles for pressure vessels, columns, towers and preheaters built to ASME Section VIII, plus seawater-cooled condensers.
Nuclear and pollution control
Spent fuel reprocessing equipment, where the absence of cobalt matters, plus flue-gas desulphurisation scrubbers, ducting and expansion joints.
Where 825 is the wrong choice. Above about 540 °C in pressure service, sensitisation and creep move the selection to Incoloy 800H/800HT or Inconel 625. In hot concentrated hydrochloric acid or wet chlorine, Hastelloy C-276 or C-22 outperform it. Where yield strength above 700 MPa is needed in the same corrosion envelope, the age-hardenable Incoloy 925 or 945 is the direct upgrade.
Incoloy 825 compared with neighbouring grades
| Property | Incoloy 825 | Inconel 625 | Incoloy 925 | Incoloy 800H |
|---|---|---|---|---|
| UNS | N08825 | N06625 | N09925 | N08810 |
| Nickel, % | 38–46 | 58 min | 42–46 | 30–35 |
| Molybdenum, % | 2.5–3.5 | 8–10 | 2.5–3.5 | — |
| Strengthening | Solid solution | Solid solution | Age hardened | Solid solution |
| Yield, min MPa | 240 | 414 | 760 | 170 |
| Max service temp. | 540 °C | 980 °C | 260 °C | 1100 °C |
| Relative cost | 1.0× | 2–3× | 2–2.5× | 0.8–1.0× |
| Chosen for | Sulphuric & phosphoric acid, sour gas | Seawater, high temperature, strength | High-strength sour service | Creep at high temperature |
Practical rule: start with Incoloy 825. Move up to Inconel 625 only when temperature or pitting resistance demands it, and to Incoloy 925 only when you need strength in the same corrosive envelope.
Frequently asked questions
What is Incoloy 825?
Incoloy 825 is a titanium-stabilised nickel-iron-chromium alloy containing roughly 38–46 % nickel, 19.5–23.5 % chromium, 2.5–3.5 % molybdenum and 1.5–3.0 % copper. It is designated UNS N08825, W.Nr. 2.4858 and NiCr21Mo. The alloy is solid-solution strengthened and is supplied in the annealed condition, not aged.
Which standard covers Incoloy 825 forgings?
Forged pieces, flanges and fittings in UNS N08825 are ordered to ASTM B564, adopted in the ASME Boiler and Pressure Vessel Code as ASME SB-564. Bar is covered by ASTM B425, plate by ASTM B424, seamless pipe and tube by ASTM B423, and the German equivalent is material number 2.4858.
Is Incoloy 825 age hardenable?
No. Incoloy 825 is solid-solution strengthened and cannot be strengthened by ageing. The correct heat treatment is a solution or stabilising anneal at 930–1010 °C followed by rapid cooling. The age-hardenable relatives are Incoloy 925 and Incoloy 945, which carry higher titanium and aluminium for that purpose.
What is the maximum service temperature of Incoloy 825?
For ASME pressure-retaining service, allowable stresses for UNS N08825 are listed up to about 540 °C (1000 °F). Above roughly 540 °C, prolonged exposure can sensitise the alloy and reduce corrosion resistance, so higher-temperature duty normally moves to Incoloy 800H, 800HT or Inconel 625.
Is Incoloy 825 suitable for sour service under NACE MR0175?
Yes. UNS N08825 is listed in NACE MR0175 / ISO 15156-3 for sour oilfield service in the solution-annealed condition, at a maximum hardness of 35 HRC. Environmental limits on H2S partial pressure, chloride content, temperature and elemental sulphur apply and must be confirmed against the specific table in the standard.
What is the difference between Incoloy 825 and Inconel 625?
Incoloy 825 is iron-balanced with 38–46 % nickel and about 3 % molybdenum, chosen for sulphuric and phosphoric acid duty at moderate cost. Inconel 625 is nickel-balanced with 8–10 % molybdenum plus niobium, giving higher strength, better pitting resistance and useful properties to about 980 °C, at roughly two to three times the price.
What sizes of Incoloy 825 forgings can be produced?
Jiangyin Jiangnan Metal Co., Ltd. open-die forges Incoloy 825 from 10 kg to 15,000 kg per piece: seamless rolled rings up to 3,000 mm outside diameter, discs and tube sheets up to 2,500 mm, round bars 60–800 mm diameter, and shafts up to 8,000 mm long. Minimum order is one piece.
Who supplies Incoloy 825 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. It supplies Incoloy 825 (UNS N08825) rings, flanges, bars, discs, shafts and tube sheets to ASTM B564 with EN 10204 3.1 or 3.2 certification. Contact +86 189 2135 9659 or sales@steelforgepieces.com.
What certification is supplied with Incoloy 825 forgings?
Every piece ships with an EN 10204 3.1 works certificate covering heat number, chemical analysis, mechanical test results, heat-treatment record and NDT report. EN 10204 3.2 certification witnessed by BV, SGS, TÜV, DNV or Lloyd's Register is available on request, as are NACE MR0175 and ASTM G28 Method A test reports.
Why is Incoloy 825 difficult to machine?
The alloy work hardens rapidly and its thermal conductivity is about 11 W/m·K, roughly a fifth of carbon steel, so heat concentrates at the cutting edge. Use rigid setups, sharp positive-rake carbide tooling, reduced surface speed, heavy feed and generous coolant, and never dwell in the cut, which glazes the surface and destroys the next pass.
Order Incoloy 825 forgings
Manufacturer, not a trading company
Jiangyin Jiangnan Metal Co., Ltd. is an open-die forging factory in Jiangyin, Jiangsu Province, China, in the Yangtze River delta forging cluster roughly 150 km from the Port of Shanghai. We forge, heat treat, test and certify Incoloy 825 in house, alongside carbon steel, alloy steel, tool steel, stainless steel and the wider nickel alloy range.
Send a drawing or a size list with the grade, quantity, specification and certification level, and you will have a quotation within one working day.
- Company
- Jiangyin Jiangnan Metal Co., Ltd.
- Factory address
- No.1 Chengxiqiao Road, Zhouzhuang Town, Jiangyin City, Jiangsu Province, China
- Telephone / WhatsApp
- +86 189 2135 9659
- Website
- www.steelforgepieces.com
- Nearest port
- Shanghai / Zhangjiagang
Data sources
Composition, property and hardness limits on this page are taken from the published requirements of the following standards. Values marked "typical" are our own production results and are not specification minima. Always order to the current issue of the applicable standard.
- ASTM B564 / ASME SB-564, Nickel Alloy Forgings (UNS N08825). ASTM International
- ASTM B425, Nickel-Iron-Chromium-Molybdenum-Copper Alloy Rod and Bar
- ASME Boiler and Pressure Vessel Code, Section II Part D, allowable stresses
- ISO 15156-3 / NACE MR0175, Materials for use in H2S-containing environments. ISO
- DIN 17744 / 17752, Wrought nickel alloys, material number 2.4858
- EN 10204, Metallic products, types of inspection documents
Page last reviewed: by the technical sales team at Jiangyin Jiangnan Metal Co., Ltd.