Incoloy 825 Plate
Key Performance Properties
- Exceptional Acid Resistance:
It stands as one of the most reliable and budget-conscious superalloys for containing concentrated sulfuric and phosphoric acids. - Temperature Stability:
It retains its mechanical durability and structural toughness from cryogenic levels up to 1000°F (538°C).Exposure above this point can slightly alter its microstructure and lower impact strength. - Non-Magnetic Behavior:
The material is entirely non-magnetic when left in its mill-annealed state.

Applications of Incoloy 825 Plate
- Acid Tanks
- Heat Exchangers
- Chemical Reactors
- Distillation Columns
- Downhole Tubes
- Offshore Platforms
- Gas Scrubbers
- Nuclear Dissolvers
- Pickling Hooks
- Heating Coils
- Exhaust Systems
- Waste Incinerators
- Process Piping
- Cryogenic Vessels
- Slurry Pumps
- Industrial Valves
Chemical Composition of Incoloy 825 Plate
| Ni | Fe | Cr | Mo | Cu | Ti | Mn | C | Si | S |
|---|---|---|---|---|---|---|---|---|---|
| 38.0 – 46.0 | ≥ 22.0 | 19.5 – 23.5 | 2.50 – 3.50 | 1.50 – 3.0 | 0.60 – 1.20 | ≤ 1.0 | ≤ 0.05 | ≤ 0.50 | ≤ 0.03 |
Metallurgical Insights & Synergies
- The Copper-Molybdenum Synergy:
The simultaneous inclusion of copper and molybdenum is highly unusual for general nickel alloys.Together,they create an incredibly robust barrier against highly reducing acids,making Incoloy 825 the industrial standard for boiling sulfuric acid solutions up to 40% concentration. - Titanium Stabilization:
When steel or nickel alloys are welded,heat causes carbon to bind with chromium,depleting the chromium at the grain boundaries.Because Incoloy 825 contains titanium,the carbon preferentially binds to the titanium instead,forming harmless titanium carbides.This allows the plate to be welded without losing its corrosion resistance.
Comparative Analysis: Incoloy 825 Plate VS. Peers
- VS. 316L Stainless Steel:
316L contains only about 10–14% Nickel.Incoloy 825’s 38–46% Nickel content makes it virtually immune to chloride-induced stress corrosion cracking,a major failure point for 316L in marine environments. - VS. Inconel 625:
Inconel 625 scales up the Nickel content to over 58% and drops Iron to under 5%.While Inconel 625 handles much higher temperatures (> 1000℉),Incoloy 825 is significantly more cost-effective for wet chemical environments due to its higher iron content.
Incoloy 825 Standards & Equivalent Designations
| Incoloy 825 Alloy | |||||
|---|---|---|---|---|---|
| Standard / System | Equivalent Designation | Product Form | ASTM | ASME | SAE AMS |
| UNS Number | UNS N08825 | Plates, Sheets & Strips | ASTM B424 | ASME SB424 | AMS 5542 |
| DIN / German Werkstoff | W.Nr. 2.4858 | Bars, Rods, Wires & Shapes | ASTM B425 | ASME SB425 | AMS 5719 |
| EN Chemical Name | NiCr21Mo | Seamless Pipes & Tubes | ASTM B423 | ASME SB423 | – |
| JIS | NCF 825 | Condenser & Heat Exchanger Tubes | ASTM B163 | ASME SB163 | – |
| BS | NA 16 | Welded Pipes & Tubes | ASTM B704 / B705 | ASME SB704 / SB705 | – |
| AFNOR | NC21FeDu | Forgings & Flanges / Fittings | ASTM B564 | ASME SB564 | – |
| Generic Trade Name | Alloy 825, Incoloy 825 | ||||
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Mechanical Properties of Incoloy 825 Plate
Room-Temperature Mechanical Properties
| Property | Minimum Specified | Typical Production Values |
|---|---|---|
| Ultimate Tensile Strength | 586 MPa (85 ksi) | 655 – 689 MPa (95 – 100 ksi) |
| Yield Strength | 241 MPa (35 ksi) | 300 – 324 MPa (43.5 – 47 ksi) |
| Elongation | 30% | 39 – 45% |
| Hardness | Max 210 HB / 95 HRB | 135 – 165 HB 75 – 85 HRB |
Mechanical Design Parameters
- Modulus of Elasticity (Young’s Modulus):
28.3 × 106 psi (195GPa) at room temperature.It drops predictably to 26.0 × 106 psi (179GPa) at 800℉. - Poisson’s Ratio:
0.31, which aligns with structural austenitic steel variants. - Shear Modulus:
10.8 × 106 psi (75GPa)
Temperature-Dependent Behavior
The metallurgical composition of Incoloy 825 stabilizes its performance across wide thermal ranges,but with specific operational boundary limits:
- Cryogenic Reliability:
At sub-zero and deep cryogenic limits down to -320℉(-196℃),the plate retains high impact toughness and does not experience a sharp ductile-to-brittle transition.Tensile and yield strengths increase slightly at lower temperatures while maintaining favorable elongation. - Elevated Temperature Limit:
Mechanical strength holds stable up to 1000℉(540℃).For pressure vessel fabrication under the ASME Boiler and Pressure Vessel Code, maximum design allowances are capped at 800℉(427℃). - The 1000℉ Microstructural Wall:
Exceeding 1000℉(540℃) introduces internal microstructural phase transformations.It causes the precipitation of harmful secondary phases that significantly drop impact strength,fracture toughness,and ductility.Therefore,it is rarely utilized for creep-rupture dominant operations.
Our Advantages in Manufacturing Incoloy 825 Plate
Vacuum Melting Precision
High-Ratio Thermo Rolling
Rapid Quench Annealing
Comprehensive NDT Compliance
FAQs About Incoloy 825 Plate
The primary difference lies in the nickel and iron content.While 316L is an iron-base stainless steel with 10–14% nickel,Incoloy 825 is a nickel-iron-chromium alloy containing 38–46% nickel.This massive boost in nickel makes Incoloy 825 virtually immune to chloride-ion SCC,a common failure mode for 316L in marine and chemical environments.Additionally,Incoloy 825 includes copper,which gives it vastly superior resistance to sulfuric and phosphoric acids compared to 316L.
Yes,Incoloy 825 exhibits excellent weldability using standard processes like GTAW/TIG,GMAW/MIG,and SMAW/Stick.Because it is stabilized with titanium,it resists intergranular corrosion in the weld HAZ.
It is typically welded using Alloy 625 filler metals (such as ERNiCrMo-3 bare wire or ENiCrMo-3 covered electrodes).This over-alloyed filler ensures the weld joint matches or exceeds the corrosion resistance of the base 825 plate.
Yes.When properly solution-annealed and processed,Incoloy 825 plates fully comply with NACE MR0175 / ISO 15156 requirements.It is widely approved for use in downstream,midstream,and upstream “sour service” environments where high levels of H2S, CO2,and chlorides are present.
- Composition & Cost:
Inconel 625 is a higher-grade,more expensive alloy with over 58% nickel and no iron base requirement.Incoloy 825 contains 38-46% nickel and ~22% iron minimum,making it much more cost-effective. - Performance:
Inconel 625 is designed for extreme high-temperature strength (up to 1800°F) and severe high-temperature oxidation.Incoloy 825 is a specialized “wet corrosion” alloy,meaning it outperforms or equals 625 in specific acidic environments (like sulfuric acid) at lower temperatures,but at a much lower material cost.
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