What is Incoloy 825?
Incoloy 825 is a high-performance nickel-iron-chromium superalloy.It is specifically engineered to provide exceptional corrosion resistance in both oxidizing and reducing chemical environments.It was created as a cost-effective upgrade to stainless steel for highly aggressive acidic conditions.
Key Performance Characteristics
Common Applications of Incoloy 825
- Downhole Oil and Gas Tubing
- Acid Pickling Equipment
- Chemical Process Heat Exchangers
- Phosphoric Acid Production
- Nuclear Fuel Reprocessing
- Flue Gas Desulfurization Scrubbers
- Offshore Marine Piping Systems
- Food and Beverage Processing
- Radioactive Waste Disposal
- Ammonium Sulfate Manufacture
Global Equivalent Grades for Alloy 825
| UNS | W.Nr. | EN | GB | JIS | AFNOR | BS |
| N08825 | 2.4858 | NiCr21Mo | NS142 NS1402 | NCF 825 | NC21FeDU | BS 3074 NA16 |
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Chemical Composition of Incoloy 825
| Ni | Fe | Cr | Mo | Cu | Ti |
| 38.0 – 46.0 | ≥ 22.0 | 19.5 – 23.5 | 2.5 – 3.5 | 1.5 – 3.0 | 0.6 – 1.2 |
| Mn | Si | C | Al | S | |
| ≤ 1.0 | ≤ 0.5 | ≤ 0.05 | ≤ 0.2 | ≤ 0.03 |
Mechanical Properties of Incoloy 825
Incoloy 825 provides excellent mechanical strength and toughness across a wide temperature range – from cryogenic up to 1000°F (540°C).It is highly prized in demanding applications requiring resistance to both reducing and oxidizing acids.
Room-Temp Mechanical Properties
| Ultimate Tensile Strength | Yield Strength | Elongation | Hardness |
| 650 – 770 MPa 95 – 112 ksi | 240 – 450 MPa 35 – 65 ksi | 30 – 45% | 130 – 180 HBW 75 – 90 Rockwell B |
Temperature Properties
- Elevated Temperatures:
The alloy retains good mechanical strength up to 1000°F (538°C).However,prolonged exposure to temperatures exceeding 1000°F can cause microstructural changes that degrade impact toughness and ductility. - Cryogenic Temperatures:
Incoloy 825 maintains exceptional toughness and impact strength at extremely low temperatures.
Physical Properties
- Density:
8.14 g/cm³ (0.294 lb/in³) - Modulus of Elasticity:
196 GPa (28.3 × 10³ ksi) at room temperature - Melting Range:
1370°F to 1400°F
Key Mechanical Characteristics
- Fabrication and Weldability:
The alloy has good ductility,making it easy to form and machine using conventional methods similar to austenitic stainless steels.It possesses excellent weldability and resists deformation or cracking under moderate loads even after repeated thermal cycling. - Stress-Corrosion Cracking:
The high nickel content of Incoloy 825 makes the alloy highly resistant to chloride-ion stress-corrosion cracking, which is a major mechanical advantage in marine and sour gas environments.
Standards for Incoloy 825
- Seamless Incoloy 825 Pipe:ASTM B423 / ASME SB423
- Welded Incoloy 825 Pipe:ASTM B705 / ASME SB705
- Cold-drawn Welded Tubes in Heat Exchangers:ASTM B704
- Wall Thickness Standard:ANSI/ASME B36.19
Welding & Interconnection of Incoloy 825
- Matching Welding Consumables:
Welding consumables of the same grade or “superalloyed” types must be used.
Inconel 625 welding wire (ERNiCrMo-3) or Incoloy 65 welding wire (ERNiCrMo-6) are typically selected for gas tungsten arc welding (GTAW) or shielded metal arc welding (SMAW). - No PWHT:
Unlike some carbon steel pipes,Incoloy 825 pipes do not require heat treatment after welding.Because titanium is added for stabilization,no carbides precipitate in the heat-affected zone during welding. - Fittings:
The piping must be equipped with Incoloy 825 flanges,elbows,and tees to ensure there are no material weaknesses along the entire pipeline.
Availability of Incoloy 825 Pipes and Tubes
| Product | Size | Wall Thickness | SMLS | Welded |
| Pipe | 1/2″ – 16″ | SCH10S, SCH40S, STD, SCH60, SCH80S, XS, SCH100, SCH120 | √ | |
| 1/2″ – 104″ | SCH5S~80S/XS | √ | ||
| Tube | 6mm ~ 204mm | 1.2mm ~ 16mm | √ | |
| Contact Us With Your Requirements For Welded Tubings | √ | |||
When should I choose a Seamless Pipe vs. a Welded Alloy 825 Pipe?
Seamless Pipes:
Used for high-pressure systems,sour gas wells,and critical chemical lines where longitudinal weld seam failure poses a safety hazard.
Welded Pipes:
Best for low-to-medium pressure applications or oversized diameters.They offer a significantly cheaper procurement budget.
Is Alloy 825 magnetic?
No.Incoloy 825 possesses a fully austenitic crystal structure and remains completely non-magnetic across room temperature down to cryogenic scales.
Does 825 pipe require Post-Weld Heat Treatment?
No,typically not.Alloy 825 is stabilized with Titanium.Titanium safely binds with the carbon during the welding heat cycle to stop chromium carbide precipitation at the grain boundaries, preventing intergranular corrosion without the need for post-weld annealing.
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