Alloy 825 (UNS N08825): High-Performance Nickel Alloy – The Go-To Choice for Broad Corrosion Resistance
Alloy 825 (UNS N08825): High-Performance Nickel Alloy – The Go-To Choice for Broad Corrosion Resistance
Alloy 825 (UNS N08825) is a versatile nickel-iron-chromium superalloy with added molybdenum, copper, and titanium. It is specifically designed for extreme industrial environments, exhibiting excellent resistance to oxidizing and reducing acid corrosion, chloride stress corrosion cracking, and pitting corrosion.
What are the uses of Inconel 825?
Inconel 825 alloy exhibits excellent corrosion resistance under various conditions, including both general and localized corrosion, making it suitable for a wide range of applications. These include chemical processing, pollution control, oil and gas extraction, acid production, pickling operations, nuclear fuel reprocessing, and radioactive waste treatment.
1. Inconel 825 Typical Chemical Composition (mass fraction, %)
| Element | Content (%) | Function | |
|---|---|---|---|
|
|
Nickel (Ni) | 38.0 – 46.0 | Matrix element; provides corrosion resistance and austenitic stability |
| Chromium (Cr) | 19.5 – 23.5 | Oxidation and corrosion resistance | |
| Iron (Fe) | ≥ 22.0 (Balance) | Base element; provides structural strength | |
| Molybdenum (Mo) | 2.5 – 3.5 | Enhances pitting and crevice corrosion resistance | |
| Copper (Cu) | 1.5 – 3.0 | Critical for sulfuric acid resistance | |
| Titanium (Ti) | 0.6 – 1.2 | Carbide stabilizer; prevents sensitization | |
| Carbon (C) | ≤ 0.05 | Low carbon for weldability | |
| Manganese (Mn) | ≤ 1.0 | Deoxidizer | |
| Silicon (Si) | ≤ 0.5 | Deoxidizer | |
| Phosphorus (P) | ≤ 0.030 | Ensures toughness | |
| Sulfur (S) | ≤ 0.030 | Ensures hot workability | |
| Aluminum (Al) | ≤ 0.20 | Supplementary strengthening |
Gnee Alloy other alloy PMI real-shot test images
2. Inconel 825 Physical Properties
| Property | Value |
|---|---|
| Density | 0.294 lb/in³; 8.14 g/cm³ |
| Magnetic Permeability | < 1.02 |
| Specific Heat (21°C) | 0.12 Btu/lb·°F; 500 J/kg·K |
| Electrical Resistivity (21°C) | 113 μΩ·cm |
| Coefficient of Thermal Expansion (from 21°C) | 7.7×10⁻⁶/°F (93°C); 8.7×10⁻⁶/°F (427°C) |
| Thermal Conductivity (21°C) | 6.4 Btu/h·ft·°F; 11.1 W/m·K |
3. Inconel 825 corrosion resistance
1. Inconel 825 Corrosion Resistance In Sulfuric Acid (Boiling Laboratory Sulfuric Acid Solution)
| Alloy | 40% H₂SO₄ | 50% H₂SO₄ |
|---|---|---|
| 316 Stainless Steel | 636 mpy (16.2 mm/a) | >1000 mpy (>25 mm/a) |
| Alloy 825 | 20 mpy (0.5 mm/a) | 11 mpy (0.28 mm/a) |
| Alloy 620 | 20 mpy (0.5 mm/a) | 17 mpy (0.4 mm/a) |
2. Inconel 825 Resistance To Chloride Stress Corrosion Cracking (U-Bend Specimen)
| Corrosive Medium | 316 Stainless Steel | AL-6XN | Alloy 825 | E-BRITE | Alloy 625 |
|---|---|---|---|---|---|
| 42% Boiling Magnesium Chloride | Failed | Mixed failure | Mixed failure | Resistant | Resistant |
| 33% Boiling Magnesium Chloride | Failed | Resistant | Resistant | Resistant | Resistant |
| 26% Boiling Sodium Chloride | Failed | Resistant | Resistant | Resistant | Resistant (corrosion resistant) |
3. Inconel 825 Resistance To Pitting And Crevice Corrosion (ASTM G-48 Method B, 10% Ferric Chloride)
| Alloy | Temperature |
|---|---|
| Alloy 825 | 27°F (-2.5°C) / 32°F (0.0°C) / 113°F (45.0°C) |
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4. Inconel 825 Resistance To Intergranular Corrosion
| Alloy | Corrosion Rate in Boiling 65% Nitric Acid | Corrosion Rate in Boiling 50% Sulfuric Acid - Iron |
|---|---|---|
| 316 Stainless Steel | 34 mpy (0.85 mm/a) | 36 mpy (0.91 mm/a) |
| 316L Stainless Steel | 18 mpy (0.47 mm/a) | 26 mpy (0.66 mm/a) |
| Alloy 825 | 12 mpy (0.30 mm/a) | 1 mpy (0.03 mm/a) |
| AL-6XN | 30 mpy (0.76 mm/a) | 19 mpy (0.48 mm/a) |
| Alloy 625 | 37 mpy (0.94 mm/a) | Not tested |
5. Inconel 825 Alloy Mechanical Properties
1. Inconel 825 Typical Room Temperature Mechanical Properties
| Yield Strength (0.2%) | Tensile Strength | Elongation | Modulus of Elasticity |
|---|---|---|---|
| 43,500 psi (300 MPa) | 100,000 psi (690 MPa) | 45% | 28.3×10⁶ psi (195 GPa) |
2. incoloy 825 High Temperature Tensile Properties (Solution Annealed)
| Test Temperature | Yield Strength | Tensile Strength | Elongation |
|---|---|---|---|
| 70°F (21°C) | 43,500 psi (300 MPa) | 100,000 psi (690 MPa) | 45% |
| 200°F (93°C) | 40,400 psi (279 MPa) | 95,000 psi (655 MPa) | 45% |
| 400°F (204°C) | 35,600 psi (245 MPa) | 92,400 psi (637 MPa) | 43% |
| 600°F (316°C) | 33,600 psi (232 MPa) | 91,700 psi (623 MPa) | 45% |
| 800°F (427°C) | 33,000 psi (228 MPa) | 88,500 psi (610 MPa) | 45% |
| 1,000°F (538°C) | 32,200 psi (222 MPa) | 85,900 psi (592 MPa) | 45% |
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6. Incoloy 825 Forming and Welding Performance
6.1 Forming Performance
The alloy exhibits excellent cold forming performance, with forming characteristics similar to other high-nickel alloys. It offers outstanding ductility for deep drawing, spinning, and bending, meeting the requirements for complex structural forming. The alloy has slightly higher strength than carbon steel, with a lower work hardening rate than conventional stainless steel, allowing for continuous multi-pass forming operations.
6.2 Welding Performance
The alloy can be welded using conventional processes such as inert gas shielded welding, shielded metal arc welding, and resistance welding, with no preheating or post-weld heat treatment required. When welding, select highly alloyed matching filler materials to ensure that the weld metal corrosion resistance is equivalent to that of the base metal. The workpiece surface must be thoroughly cleaned before welding to maintain surface cleanliness and preserve corrosion resistance. Prolonged exposure in the sensitization temperature range of 593–816°C should be avoided.
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7. Incoloy 825 Heat Treatment Processes
7.1 Solution Annealing
Heat to 927–1038°C, hold until the workpiece reaches uniform temperature, then cool rapidly by air cooling or water quenching. This achieves softening after forming and grain refinement.
7.2 Stabilization Treatment
To enhance resistance to intergranular corrosion, a stabilization treatment is required by holding at 870–955°C for 1 hour or more.
7.3 Precautions
Heat treatment in high-sulfur, high-temperature environments should be avoided to prevent degradation of alloy properties.
8. Gnee Alloy offers processing services
Gnee Alloy incoloy 825 product processing services
9. incoloy 825 Typical Application Areas
| Subsection | Application Areas |
|---|---|
| 8.1 Oil & Gas Industry | Seawater-cooled heat exchangers, evaporators, scrubbers, dip pipes, offshore oil and gas pipelines and fittings |
| 8.2 Chemical Pickling Equipment | Heating coils, tanks, boilers, baskets, chains, etc., used in sulfuric acid pickling production lines |
| 8.3 Phosphoric Acid Production Equipment | Heat exchangers, evaporators, scrubbers, dip pipes |
| 8.4 Food Processing Industry | Food-grade corrosion-resistant structural components |
| 8.5 Other Demanding Service Conditions | Corrosion-resistant structural components for chemical applications, seawater treatment equipment, heat exchange equipment in corrosive environments |
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Why Choose Gnee as Your Nickel-Based Alloy Supplier
✅ Over 18 years of export experience, products sold to more than 80 countries
✅ Certified by ISO, SGS, and BV
✅ Global inventory of Inconel, Hastelloy, Incoloy, and Monel alloy tubing, plates, and bars
✅ Custom processing services available – including cutting, polishing, CNC machining, and packaging
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Gnee Alloy incoloy 825 Certificate
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📦 Packaging and Shipping
All Nickel Based Alloy products are packaged using the following methods:
Wooden pallets or crates
Moisture-proof packaging
Labels with furnace number, standard, and size labels
Shipped worldwide by sea, air, or express
Gnee Alloy 825 Alloy Product Packing
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FAQ
Q：Is Incoloy 825 better than Incoloy 800?
A：If you need flanges that can withstand extreme temperatures, then Incoloy 800 is a better choice. However, if your project involves acidic environments or requires resistance to stress corrosion cracking and pitting, then Incoloy 825 is a better choice.
Q：What is Alloy 825?
A：Alloy 825 (usually referred to by the brand name Incoloy 825) is a titanium-stabilized austenitic nickel-iron-chromium alloy with the addition of key molybdenum and copper elements. It is specially designed to provide excellent corrosion resistance, maintaining superior performance even in oxidizing and reducing corrosive environments.
Q：Is Alloy 825 magnetic?
A：Our customers currently use it in applications including valve assemblies, thermocouple sheaths and sensors, fasteners, and some downhole tools that utilize its non-magnetic properties.
Q：Is Alloy 825 a Monel alloy?
A：In summary, Incoloy 825 and Monel are two distinct alloys with unique properties and applications. Incoloy 825 exhibits excellent resistance to chloride stress corrosion cracking and high-temperature performance, making it suitable for the chemical, oil, and gas industries.
