Incoloy 825 · UNS N08825 · W. Nr. 2.4858 · NS142 · NiCr21Mo
Incoloy 825 (N08825): composition, properties, fittings and flanges
Incoloy 825 (UNS N08825, W. Nr. 2.4858, Chinese NS142) is a titanium-stabilised Ni-Fe-Cr-Mo-Cu alloy with 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. The titanium stabilisation prevents sensitisation during welding, so welded fabrications resist intergranular…
- UNS
- N08825
- W. Nr.
- 2.4858
- Density
- 8.14 g/cm³ (0.294 lb/in³)
- Key strength
- 585 MPa / 85 ksi
Identification and standards
| Short form | Incoloy 825 · UNS N08825 · W. Nr. 2.4858 · NS142 · NiCr21Mo |
|---|---|
| Classification | Titanium-stabilised nickel-iron-chromium-molybdenum-copper alloy |
| UNS | N08825 |
| Werkstoff number | 2.4858 |
| Material family | Incoloy Alloys |
Chemical composition
| Element | Composition (wt %) | Why it is there |
|---|---|---|
| Nickel (Ni) | 38.0 - 46.0 | Chloride SCC immunity, caustic and acid resistance |
| Chromium (Cr) | 19.5 - 23.5 | Oxidising acid resistance |
| Iron (Fe) | 22.0 min | Matrix |
| Molybdenum (Mo) | 2.5 - 3.5 | Pitting and crevice corrosion resistance |
| Copper (Cu) | 1.5 - 3.0 | Sulphuric and phosphoric acid resistance |
| Titanium (Ti) | 0.60 - 1.20 | Stabilises carbon, prevents weld sensitisation |
| Aluminium (Al) | 0.20 max | - |
| Manganese (Mn) | 1.00 max | - |
| Silicon (Si) | 0.50 max | - |
| Carbon (C) | 0.05 max | - |
| Sulphur (S) | 0.030 max | - |
Note Single figures are maximum limits unless shown as a range. Always confirm against the heat-specific EN 10204 3.1 certificate supplied with your order.
Mechanical properties
| Tensile strength, min (annealed, ASTM B424) | 585 MPa / 85 ksi |
|---|---|
| 0.2 % yield strength, min | 220 MPa / 32 ksi |
| Elongation in 2 in, min | 30 % |
| Typical hardness, annealed | 150 - 200 HB |
| Typical pitting resistance equivalent number | About 30 - 33 |
| Typical service temperature range | -196 °C to 540 °C |
Warning Values depend on product form, section thickness and heat treatment. Larger sections generally achieve lower strength than thin product; always design against the applicable code allowable stress rather than these figures.
Physical properties
| Density | 8.14 g/cm³ (0.294 lb/in³) |
|---|---|
| Melting range | 1370 - 1400 °C (2500 - 2550 °F) |
| Modulus of elasticity | 196 GPa (28.4 x 10⁶ psi) |
| Thermal conductivity at 20 °C | 10.9 W/m·K |
| Mean coefficient of thermal expansion, 20-100 °C | 14.0 µm/m·°C |
| Electrical resistivity at 20 °C | 1.13 µΩ·m |
Specifications by product form
| Plate / sheet / strip | ASTM B424 / ASME SB-424 |
|---|---|
| Bar / rod / shapes | ASTM B425 / ASME SB-425 |
| Seamless pipe & tube | ASTM B423 / B163 / ASME SB-423 |
| Welded pipe & tube | ASTM B705 / B704 |
| Forgings & flanges | ASTM B564 / ASME SB-564 (UNS N08825) |
| Butt weld fittings | ASTM B366 / ASME SB-366 (WP825 / WPH825) |
| Welding consumables | ERNiFeCr-1 wire (AWS A5.14), ENiFeCr-1 electrode |
| UNS / EN / China | UNS N08825 · W. Nr. 2.4858 · GB NS142 / 0Cr21Ni42Mo3Cu2Ti |
Product forms available
Hangbo supplies this grade in the following forms. Sizes outside the listed range can often be produced to order.
- Seamless pipe and tube including downhole tubulars
- Forged flanges to ASME B16.5 Class 150-2500
- Butt weld elbows, tees, reducers and stub ends to ASME B16.9
- Machined valve bodies, pump parts and instrument manifolds
Typical applications
- Sulphuric acid pickling tanks, heating coils and acid recovery plants
- Phosphoric acid production, evaporators and fertiliser plants
- Oil and gas tubulars, gathering lines, heat exchangers and acid gas handling
- Seawater cooled heat exchangers, piping and condensers
- Pollution control scrubbers, waste incineration and ash handling systems
- Nuclear fuel reprocessing and spent fuel handling equipment
- Hydrometallurgical extraction vessels, agitators and launders
Welding, forming and machining
- Welding
- Excellent as-welded performance thanks to titanium stabilisation. Use ERNiFeCr-1 filler with GTAW or GMAW, low heat input, interpass temperature below 150 °C and inert backing gas on root passes.
- Hot forming
- Hot work between 1150 °C and 900 °C, followed by solution annealing at 940-1010 °C and rapid cooling.
- Machining
- Standard austenitic practice with carbide tooling, positive rake and consistent feed to stay under the work-hardened layer.
- Pickling
- Descale by abrasive blasting followed by HF-HNO₃ pickling; verify intergranular corrosion acceptance with ASTM G28 or A262 Practice B where specified.
Buy Incoloy 825 from Hangbo
Material is supplied with full heat-number traceability, solution annealing or ageing performed under calibrated furnace control, and an EN 10204 3.1 certificate covering chemical analysis, mechanical properties, heat treatment records and the agreed NDT scope. Positive material identification and third party inspection and test reports from SGS are available for critical service.