UNS N08825 at a glance
- Grade
- UNS N08825, also written Incoloy® 825, Alloy 825, 825
- UNS number
- N08825
- Werkstoff / DIN
- 2.4858 / X5NiCrMoCuTi20-18, NiCr21Mo
- Alloy family
- Nickel-iron-chromium-molybdenum-copper, austenitic, not hardenable by heat treatment
- Nominal chemistry
- 42Ni, 22Cr, 3Mo, 2Cu, 0.9Ti, bal. Fe
- Forging standard
- ASTM B564 / ASME SB-564
- Bar and forging stock
- ASTM B425 / ASME SB-425, BS 3076 NA16
- Delivery condition
- Solution annealed 920 to 980 °C, rapid cooled
- Typical service range
- Cryogenic to 540 °C (1000 °F)
- Density
- 8.14 g/cm³ (0.294 lb/in³)
- Melting range
- 1370 to 1400 °C (2500 to 2550 °F)
- Sour service
- Listed in NACE MR0175 / ISO 15156-3 within the stated environmental limits
- Certification
- EN 10204 3.1 or 3.2, third-party witnessed
- Forged by
- Jiangyin Jiangnan Metal Co., Ltd., Jiangyin, Jiangsu, China
What UNS N08825 is, and when to specify it
UNS N08825 was developed in the 1950s from Alloy 800 to handle aqueous corrosion that Alloy 800 and the standard austenitic stainless steels cannot. Nickel was raised to about 42%, molybdenum and copper were added, and titanium was included as a stabiliser. The alloy performs in both oxidising and reducing acids, which is uncommon. Most grades handle one or the other.
Each addition has a defined function, and this decides whether N08825 suits a given service.
- Nickel, 38 to 46%. Austenitic alloys above roughly 35% nickel are not susceptible to chloride stress-corrosion cracking. That is the usual reason for replacing 316L or 904L with N08825 in hot chloride-bearing process streams.
- Molybdenum, 2.5 to 3.5%. Raises resistance to pitting and crevice corrosion and to reducing acids.
- Copper, 1.5 to 3.0%. The specific addition for sulfuric acid, and the main difference from Alloy 800 at intermediate acid concentrations.
- Chromium, 19.5 to 23.5%. Carries the passive film against oxidising conditions such as nitric acid.
- Titanium, 0.6 to 1.2%. Ties up carbon so that chromium carbides do not form at grain boundaries during welding. N08825 weldments therefore resist intergranular attack in most services without a post-weld solution anneal.
Specify N08825 for sulfuric acid, phosphoric acid, sour gas, seawater injection duty and pickling plant at temperatures up to about 540 °C. It is not a high-temperature structural alloy. Prolonged exposure above roughly 550 °C precipitates phases that reduce ductility. For sustained load at higher temperature, use Alloy 800HT, Inconel 617 or Haynes 230.
Chemical composition of UNS N08825
Composition limits are per ASTM B564 / ASME SB-564 and ASTM B425 for UNS N08825, in weight percent. The three highlighted rows are the additions that separate this grade from Alloy 800.
| Element | Minimum % | Maximum % | Function in the alloy |
|---|---|---|---|
| Nickel (Ni) | 38.0 | 46.0 | Stabilises the austenite and resists chloride stress-corrosion cracking |
| Chromium (Cr) | 19.5 | 23.5 | Passive film for oxidising media such as nitric acid |
| Iron (Fe) | 22.0 | balance | Base element, keeps cost well below nickel-base grades |
| Molybdenum (Mo) | 2.5 | 3.5 | Pitting and crevice corrosion resistance, reducing acids |
| Copper (Cu) | 1.5 | 3.0 | Specific addition for sulfuric acid resistance |
| Titanium (Ti) | 0.6 | 1.2 | Stabiliser, ties up carbon so the weld HAZ resists intergranular attack |
| Carbon (C) | – | 0.05 | Held low to limit chromium carbide precipitation |
| Manganese (Mn) | – | 1.0 | Deoxidiser, combines with sulfur |
| Silicon (Si) | – | 0.5 | Deoxidiser |
| Aluminium (Al) | – | 0.2 | Residual limit from deoxidation |
| Sulfur (S) | – | 0.03 | Kept low for hot workability |
| Phosphorus (P) | – | 0.02 | House limit. ASTM B425 does not specify P for N08825 |
Table compiled by Jiangyin Jiangnan Metal Co., Ltd. from ASTM B564 and ASTM B425. Every heat is supplied with a ladle analysis on the mill certificate. Product analysis on the finished forging can be added on request. The 0.02% phosphorus limit is our own house practice; ASTM B425 does not specify phosphorus for this grade.
Mechanical properties of UNS N08825 forgings
Specified minimums, annealed condition
Two specifications are in common use for this grade and they set different figures. ASTM B564 governs most North American and oil and gas orders. The EN figures appear on European chemical plant drawings. Both are minima that a mill certificate must meet, not typical values. State on the enquiry which one governs.
| Property | ASTM B564 / SB-564 | EN / W.Nr. 2.4858 |
|---|---|---|
| Tensile strength Rm, min | 586 MPa (85 ksi) | 550 N/mm² |
| Yield strength Rp0.2, min | 241 MPa (35 ksi) | 220 N/mm² |
| Elongation A5, min | 30 % | 30 % |
| Hardness | not mandated | ≤ 200 HB |
Typical as-delivered values
Solution-annealed N08825 forgings normally test above both sets of minima. The values below are representative of our production and vary with section size, forging reduction and cooling rate.
| Property | Typical range, metric | Typical range, imperial |
|---|---|---|
| Tensile strength | 590 to 730 MPa | 86 to 106 ksi |
| Yield strength 0.2% | 250 to 380 MPa | 36 to 55 ksi |
| Elongation | 35 to 50 % | 35 to 50 % |
| Reduction of area | 55 to 75 % | 55 to 75 % |
| Hardness | 130 to 180 HB | 130 to 180 HB |
| Impact energy, Charpy V, +20 °C | ≥ 120 J | ≥ 89 ft·lb |
Source: Jiangyin Jiangnan Metal Co., Ltd., UNS N08825 forging specification. Typical values are for design screening only. The mill test certificate issued with each forging governs acceptance.
UNS N08825 does not respond to ageing. It is a solid-solution alloy, and strength can be raised only by cold work. Where a drawing calls for aged or precipitation-hardened 825, the intended grade is usually Incoloy 925 (N09925) or Incoloy 945 (N09945). We raise this at quotation stage.
Physical properties of UNS N08825
| Property | Metric | Imperial |
|---|---|---|
| Density | 8.14 g/cm³ | 0.294 lb/in³ |
| Melting range | 1370 to 1400 °C | 2500 to 2550 °F |
| Modulus of elasticity | 196 GPa | 28.4 × 10⁶ psi |
| Specific heat | 440 J/kg·K | 0.105 Btu/lb·°F |
| Thermal conductivity, 20 °C | 11.1 W/m·K | 77 Btu·in/ft²·h·°F |
| Mean expansion, 20 to 100 °C | 14.0 µm/m·K | 7.8 × 10⁻⁶ in/in·°F |
| Electrical resistivity | 1.13 µΩ·m | 680 Ω·circ mil/ft |
| Magnetic permeability | approx. 1.005 | essentially non-magnetic |
Two of these figures affect ordering. Density at 8.14 g/cm³ is about 4% above carbon steel, so a forged weight scaled from a steel drawing comes out light. Thermal conductivity is around a quarter that of carbon steel, so N08825 forgings need slower heating and longer soak times, and machining heat stays at the tool tip instead of leaving in the chip.
Alloy 825 against 316L, 904L and Alloy 625
These four grades cover most corrosion service enquiries. The choice usually turns on chloride content, acid type and budget rather than on strength.
| Criterion | 316L | 904L | Alloy 825 | Alloy 625 |
|---|---|---|---|---|
| UNS number | S31603 | N08904 | N08825 | N06625 |
| Nominal Ni | 12% | 25% | 42% | 60% |
| Nominal Mo | 2.5% | 4.5% | 3% | 9% |
| Chloride SCC | Susceptible | Improved | Resistant | Resistant |
| Sulfuric acid | Poor | Good | Good, copper bearing | Good |
| Hot seawater, crevice | Poor | Moderate | Moderate | Excellent |
| Upper service temp. | approx. 800 °C* | approx. 400 °C | 540 °C | 980 °C |
| Relative cost per kg | 1× | 2 to 3× | 4 to 5× | 8 to 10× |
| Choose it when | Mild service, chlorides low | Dilute sulfuric acid, moderate chlorides | Sour gas, sulfuric or phosphoric acid, pickling, chloride SCC risk | Hot chlorides, seawater, high temperature, high strength |
*The figure for 316L is oxidation resistance, not corrosion service. Relative cost is indicative of forged bar stock and moves with the nickel and molybdenum markets.
Where the failure mode is chloride stress-corrosion cracking or attack by sulfuric or phosphoric acid, and the temperature stays below 540 °C, Alloy 825 is normally the cheapest grade that solves it. For hot seawater or concentrated hot chlorides, move up to Alloy 625 or Hastelloy C-276.
UNS N08825 equivalent designations
| System | Designation |
|---|---|
| UNS, USA | N08825 |
| Werkstoff Nr., Germany | 2.4858 |
| DIN / EN name | X5NiCrMoCuTi20-18, NiCr21Mo |
| BS, UK | NA16, BS 3076 |
| JIS, Japan | NCF 825 |
| AFNOR, France | Z1 NCDU 42-22, nearest |
| GB, China | NS1402, 0Cr21Ni42Mo3Cu2Ti |
| ISO | NW 8825 |
| Trade names | Incoloy® 825, Nicrofer® 4221, Sanicro® 41, Böhler L314 |
Designations marked as nearest are close but not identical. Where a code case, PED approval or design registration is involved, order to the UNS number and check the equivalence against the mill certificate rather than relying on a cross-reference table.
Incoloy® is a registered trademark of Special Metals Corporation, Nicrofer® of VDM Metals, Sanicro® of Sandvik. Jiangyin Jiangnan Metal Co., Ltd. is not affiliated with, sponsored by or endorsed by these trademark holders. Material we produce is correctly described as UNS N08825 / ASTM B564 / W.Nr. 2.4858, the same generic specification, forged independently. The trade names appear here only to identify the equivalent material.
Applicable standards by product form
| Product form | ASTM | ASME |
|---|---|---|
| Forgings, our core product | B564 | SB-564 |
| Rod, bar and forging stock | B425 | SB-425 |
| Plate, sheet and strip | B424 | SB-424 |
| Seamless pipe and tube | B423 | SB-423 |
| Welded pipe | B705 | SB-705 |
| Welded tube | B704 | SB-704 |
| Fittings | B366 | SB-366 |
For sour oilfield service, UNS N08825 is listed in NACE MR0175 / ISO 15156-3 as a corrosion-resistant alloy, subject to the delivery condition, hardness limit and the environmental limits on H₂S partial pressure, chloride concentration, pH and temperature given in the current edition. State the service environment on the enquiry and we will confirm the delivery condition and the hardness to be certified. Pressure-retaining design under the ASME Boiler and Pressure Vessel Code and ASME B31.3 uses the SB-564 allowable stresses. The practical ceiling of about 540 °C is set by ductility loss, not by the code table alone.
UNS N08825 forgings we produce
Jiangyin Jiangnan Metal Co., Ltd. is an open-die forging factory. Every item below is forged to the customer drawing or dimensional sketch. There is no fixed catalogue and no tooling charge for open-die work.
Size and weight capability
| Product form | Dimensional range | Unit weight |
|---|---|---|
| Seamless rolled rings | OD 200 to 3,000 mm, height to 800 mm | 20 to 8,000 kg |
| Round bars | Ø80 to 800 mm, length to 6,000 mm | 20 to 6,000 kg |
| Discs, tube sheets | Ø200 to 2,500 mm, thickness to 600 mm | 30 to 10,000 kg |
| Shafts, sleeves, blocks | to 6,000 mm long | to 10,000 kg |
Machining allowance is normally 6 to 20 mm per surface depending on section size, unless the drawing states otherwise. We also supply finish-machined parts to print. Plant includes 1 t, 3 t, 5 t and 9 t open-die hammers, hydraulic presses to 5,000 t, and 3 m and 6 m seamless ring-rolling mills.
How we make UNS N08825 forgings
- Melting
N08825 stock is melted by EAF with AOD or VOD refining. ESR remelting is available where the specification or the service calls for improved cleanliness and reduced segregation.
- Billet inspection
Heat chemistry is verified by spectrometer against ASTM B564 and B425 limits, including the Mo, Cu and Ti windows that define the grade, before any material is heated.
- Open-die forging
Forged on hydraulic presses with a controlled reduction ratio to close porosity and develop grain flow that follows the part contour. Rings are ring-rolled seamless. Final reductions are taken between 870 and 980 °C, which preserves the corrosion performance of the finished part.
- Solution annealing
Held at 920 to 980 °C, preferably 940 °C plus or minus 10 °C, for a time proportional to section thickness, then cooled rapidly. Heavy sections are water quenched. Where the part will be welded and exposed to an intergranular corrosion risk, a stabilising anneal of one hour or more at 870 to 955 °C is applied. N08825 is never age hardened.
- Rough or finish machining
Turned, bored, drilled and faced to the drawing, with agreed machining allowance or to final dimensions.
- Non-destructive testing
Ultrasonic examination to EN 10228-3, SEP 1921, ASTM A388 or the nominated class. Liquid penetrant and dimensional inspection as required.
- Certification and despatch
EN 10204 3.1 mill certificate as standard, 3.2 with third-party witness by TÜV, BV, LR, SGS or DNV on request. Hard stamped, preserved and packed for sea or air freight.
Where UNS N08825 forgings are used
| Industry | Components forged in UNS N08825 |
|---|---|
| Oil and gas, subsea | Wellhead and Christmas tree components, hangers, valve bodies, bonnets and seat rings, subsea connector rings, downhole tool bodies, sour-service flanges |
| Chemical processing | Sulfuric and phosphoric acid plant hardware, evaporator and crystalliser components, agitator and pump shafts, forged nozzles, column and tower internals |
| Pressure vessels and heat exchangers | Forged tube sheets, shell flanges, blind covers, girth rings and nozzles for shell and tube exchangers, air receivers |
| Pollution control | Flue-gas desulfurisation forgings, scrubber flanges and rings, waste and spent-acid processing hardware |
| Marine and seawater systems | Propeller and pump shafts, seawater injection pump components, sleeves and bushings, heat exchanger tube sheets |
| Pickling and metal finishing | Pickling plant baskets, rolls, rings and hangers exposed to mixed sulfuric and nitric acid |
| Nuclear and specialty | Spent fuel reprocessing dissolver components, acid production hardware, tank truck and pressure vessel fittings |
| Power and rotating equipment | Compressor and turbine hardware in corrosive gas streams, gearbox and coupling components, forged rolls |
All of these duties involve a wet, acidic or chloride-bearing environment below about 540 °C, where a forged part must not crack, pit or suffer intergranular attack at a weld. Forging rather than casting or fabrication gives continuous grain flow and a sound, tested section, which pressure-retaining and rotating parts require.
Testing, inspection and certification
- Chemical analysis. Spectrometric ladle analysis on every heat, with product analysis on the finished forging on request.
- Mechanical testing. Room-temperature tensile, yield and elongation per ASTM B564. Hardness, Charpy impact and elevated-temperature tensile to specification.
- Ultrasonic testing. EN 10228-3, SEP 1921 Class C, D or E, ASTM A388, or the nominated acceptance class.
- Surface NDT. Liquid penetrant examination per ASTM E165 / ASME V Article 6.
- Intergranular corrosion. ASTM G28 method A, or ASTM A262 practice as agreed, the usual acceptance test for stabilised grades after welding.
- Grain size and microstructure. Per ASTM E112, with metallographic examination on request.
- Sour service. Hardness survey and delivery condition certified to NACE MR0175 / ISO 15156-3 when the order calls for it.
- 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.
Frequently asked questions about UNS N08825
What is UNS N08825?
UNS N08825 is a nickel-iron-chromium alloy with additions of molybdenum, copper and titanium. Nominal composition is 42% nickel, 22% chromium, 3% molybdenum, 2% copper and 0.9% titanium, balance iron. It is a single-phase austenitic alloy and is not hardenable by heat treatment. Nickel gives resistance to chloride stress-corrosion cracking. Molybdenum and copper resist reducing acids such as sulfuric and phosphoric acid. Chromium covers oxidising conditions. Titanium stabilises the alloy against intergranular attack after welding. It is also known as Incoloy 825, Alloy 825 and W.Nr. 2.4858.
Is UNS N08825 the same as Incoloy 825?
Yes, they are the same material. UNS N08825 is the neutral designation in the Unified Numbering System. Incoloy is a registered trademark of Special Metals Corporation, so material produced by other mills is correctly described as Alloy 825 or UNS N08825. On a purchase order, specify UNS N08825 with ASTM B564 for forgings so the requirement is unambiguous and the mill certificate can be checked against it.
Can UNS N08825 be age hardened?
No. UNS N08825 is a solid-solution austenitic alloy and cannot be strengthened by heat treatment. The only heat treatment applied to N08825 forgings is a solution or stabilising anneal at 920 to 980 °C followed by rapid cooling. Strength can be raised only by cold work. Where a precipitation-hardened alloy with similar corrosion resistance is required, specify Incoloy 925 (UNS N09925) or Incoloy 945 (UNS N09945).
What is the maximum service temperature of UNS N08825?
UNS N08825 is normally used up to about 540 °C (1000 °F). Above roughly 550 °C, prolonged exposure precipitates secondary phases that reduce ductility and impact toughness, and the corrosion advantage of the alloy is lost. For sustained service at higher temperature, use Alloy 800H, Alloy 800HT, Inconel 617 or Haynes 230. At the cold end of the range the alloy keeps good toughness down to cryogenic temperatures.
Which standard covers UNS N08825 forgings?
ASTM B564 (ASME SB-564) covers nickel alloy forgings including UNS N08825. Related specifications are ASTM B425 for rod, bar and forging stock, ASTM B424 for plate, sheet and strip, ASTM B423 for seamless pipe and tube, and ASTM B366 for fittings. British Standard BS 3076 NA16 covers bar. For sour oilfield service the material must also meet NACE MR0175 / ISO 15156-3.
Is UNS N08825 approved for sour service under NACE MR0175?
UNS N08825 is listed in NACE MR0175 / ISO 15156-3 as a corrosion-resistant alloy for sour service, subject to the delivery condition, hardness limit and the environmental limits on H₂S partial pressure, chloride content, pH and temperature stated in the current edition for the relevant material group. State the intended service environment on the enquiry and Jiangyin Jiangnan Metal Co., Ltd. will confirm the delivery condition and hardness limit to be certified on the mill certificate.
What is the difference between Incoloy 825 and Inconel 625?
Incoloy 825 (UNS N08825) is iron based with about 42% nickel and 3% molybdenum. Inconel 625 (UNS N06625) is nickel based with about 60% nickel, 9% molybdenum and 3.5% niobium. Alloy 825 is the economical choice for sulfuric and phosphoric acid, pickling plant and many sour oil and gas duties. Alloy 625 has higher resistance to pitting and crevice corrosion in seawater and hot chlorides, higher strength and a wider temperature range, at a significantly higher price per kilogram. Where the environment contains hot concentrated chlorides or the design temperature exceeds 540 °C, specify 625.
What heat treatment is applied to UNS N08825 forgings?
Solution or stabilising annealing between 920 and 980 °C, preferably 940 °C plus or minus 10 °C, held for a time proportional to section thickness and then cooled rapidly. Heavy sections are water quenched. Rapid cooling from the annealing temperature preserves corrosion resistance. Where the forging will be welded and then exposed to an intergranular corrosion risk, a stabilising anneal of at least one hour between 870 and 955 °C is applied. No ageing treatment is used because the alloy does not precipitation harden.
What sizes of UNS N08825 forgings can you supply?
Jiangyin Jiangnan Metal Co., Ltd. forges UNS N08825 seamless rolled rings from 200 to 3,000 mm outside diameter, round bars from 80 to 800 mm diameter and up to 6,000 mm long, discs and tube sheets from 200 to 2,500 mm diameter, and shafts, sleeves and blocks up to 6,000 mm long, with single-piece weights up to about 10,000 kg. Every part is forged to the customer drawing. Open-die work needs no dies, so there is no tooling charge and no minimum quantity by piece.
Do you supply an EN 10204 3.1 or 3.2 certificate?
Yes. Every UNS N08825 forging ships with an EN 10204 3.1 mill test certificate as standard, showing the heat number, ladle analysis, mechanical results, heat treatment record and NDT results, with hard stamping for traceability. EN 10204 3.2 certification witnessed by a third party such as TÜV, BV, LR, SGS or DNV is available when requested at the time of order.
How long does a UNS N08825 forging take to produce?
Lead time depends on whether the grade is in raw stock and on the size of the forging. Simple rings and discs from stock material typically run 25 to 40 days. Parts needing a new melt, ESR remelting, heavy machining or third-party witnessed inspection take longer. Send the drawing and we will confirm a firm date with the quotation.
Who supplies open-die forged UNS N08825 parts 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 forges UNS N08825 (Incoloy 825) and other nickel alloys, stainless steels, tool steels, alloy steels and carbon steels into seamless rolled rings, flanges, round bars, discs, shafts, sleeves, bushings and tube sheets to ASTM B564, and exports worldwide. Enquiries: sales@steelforgepieces.com or +86 189 2135 9659.
Request a quotation for UNS N08825 forgings
Send a drawing, a sketch, or the dimensions and quantity. We quote open-die forgings in UNS N08825 with no tooling charge and no piece minimum.
Useful details if you have them: grade and standard (UNS N08825 / Incoloy 825 / ASTM B564), product form, dimensions with machining allowance, quantity, delivery condition, NDT class, certificate type (EN 10204 3.1 or 3.2), sour service requirement and required delivery date.
- Company
- Jiangyin Jiangnan Metal Co., Ltd.
- Business
- Open-die forging factory
- 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
Email your drawing for a quote
Cite this page: Jiangyin Jiangnan Metal Co., Ltd. (2026). UNS N08825 Forgings: chemical composition, mechanical properties, heat treatment and size capability. Jiangyin, Jiangsu, China. https://www.steelforgepieces.com/Nickel-Alloy/UNS-N08825.html