Nickel Alloy 825 / Incoloy® 825 – Properties, Applications and Technical Data
Alloy 825, also known as Incoloy® 825, is a nickel-iron-chromium alloy with the addition of molybdenum, copper and titanium, developed for very good corrosion resistance in aggressive chemical environments.
The alloy combines resistance to both oxidizing and reducing acids with good mechanical strength and excellent weldability. It is widely used in the chemical process industry, energy, offshore and environmental technology where long-term operational reliability is crucial.
Properties of Alloy 825
Alloy 825 is a solid solution hardened nickel alloy where molybdenum and copper improve resistance to reducing environments such as sulfuric acid and phosphoric acid, while chromium contributes to resistance to oxidizing media.
Titanium stabilizes the alloy against sensitization and intergranular corrosion, making the material particularly suitable for welded structures.
Type: Nickel-iron-chromium-molybdenum alloy
Alloy: Ni-Fe-Cr-Mo-Cu-Ti (Alloy 825)
Structure: Austenitic nickel-based alloy
Designations: Alloy 825, Incoloy® 825, UNS N08825, Werkstoffnr 2.4858
Standards: ASTM B423, ASTM B424, ASTM B425, ASTM B564
Advantages
- Excellent resistance to both oxidizing and reducing acids
- Very good resistance to pitting and crevice corrosion
- Good resistance to stress corrosion cracking
- Stable structure at welding thanks to titanium alloy
- Good mechanical strength at both room temperature and elevated temperature
Limitations
- Higher material cost than standard stainless steels
- Lower strength than some precipitation-hardenable superalloys
- Can be more demanding to machine than austenitic stainless
Typical applications
Chemical process industry
Heat exchangers, reactors, piping and pressure vessels in aggressive acid environments.
Oil & Gas
Components for acidic environments and equipment exposed to chlorides and hydrogen sulfide.
Environmental engineering
Flue gas cleaning, scrubbers and pollution control systems.
Marine & Offshore
Equipment where the combination of corrosion resistance and strength is crucial.
Corrosion resistance
Alloy 825 offers very good resistance to sulfuric acid, phosphoric acid, nitric acid and organic acids as well as to chloride-containing environments.
The material also has good resistance to stress corrosion cracking and intergranular corrosion, making it well suited for welded structures in demanding environments.
Environments where Alloy 825 performs well
- Oxidizing and reducing acids
- Chloride-containing process environments
- Sour gas (H₂S)
- Chemical process equipment
Environments to avoid
- Applications where simpler stainless materials provide sufficient performance
- Extremely high temperatures above the material's design limit
Technical data (annealed state)
| Yield strength (0.2%) |
~220–310 MPa |
| Tensile strength |
~550–750 MPa |
| Elongation at break |
~30–45% |
| Density |
~8.14 g/cm³ |
| Modulus of elasticity |
~200 GPa |
| Recommended maximum temperature |
≤540°C |
| Weldability |
Very good – recommended filler metal INCOLOY® 65 and welding electrodes INCOLOY® 135 |
With a global network of reliable suppliers, we offer customized solutions and fast access to the right nickel-based alloy for your needs.
Contact us if you need technical advice or a quote – we will help you find the right material for your application.
Buy Alloy 825 from HARALD PIHL – your specialist in corrosion-resistant nickel alloys with global delivery.
Our strengths
- ISO 9001 and AS9120 certified quality management
- Full traceability according to EN 10204 3.1
- Materials according to ASTM, ASME and international standards
- Cutting and adaptation according to drawing
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