Incoloy 28丨UNS N08028
Incoloy 28 (Alloy 28 / UNS N08028) is a highly alloyed nickel-iron-chromium stainless alloy designed for exceptional corrosion resistance in sulfuric acid, phosphoric acid, and chloride-containing environments. Combining high chromium, nickel and molybdenum contents, Incoloy 28 offers superior resistance to pitting, crevice corrosion and stress corrosion cracking while maintaining excellent mechanical properties and weldability. J&A Alloy supplies Incoloy 28 in pipe, tube, plate, sheet, bar, flange, and fitting forms with full material traceability and global delivery.
Incoloy 28 Supplier & Manufacturer
Incoloy 28, also known as Alloy 28 or UNS N08028, is a high-performance nickel-iron-chromium alloy developed for service in highly corrosive chemical processing environments. Its elevated chromium and molybdenum contents provide excellent resistance to localized corrosion, while its high nickel content enhances resistance to chloride stress corrosion cracking. The alloy performs exceptionally well in sulfuric acid, phosphoric acid, organic acids, and chloride-containing media, making it a popular choice for chemical processing, oil & gas, pollution control, and marine applications.
Compared with conventional stainless steels and many standard corrosion-resistant alloys, Incoloy 28 offers an excellent balance of corrosion resistance, mechanical strength, and fabrication characteristics. Its ability to withstand aggressive environments while remaining readily weldable and formable makes it a cost-effective solution for critical industrial equipment and piping systems.
Features of Incoloy 28
- Excellent resistance to sulfuric acid and phosphoric acid.
- Outstanding resistance to pitting and crevice corrosion.
- Superior resistance to chloride stress corrosion cracking.
- Good resistance to seawater and chloride-containing environments.
- Excellent weldability and fabrication properties.
- High mechanical strength and toughness.
- Suitable for oxidizing and moderately reducing environments.
- Good resistance to intergranular corrosion.
- Available in a wide range of product forms.
- Complies with international ASTM and ASME standards.
Chemical Composition of Incoloy 28
| Element | Content (%) |
|---|---|
| Nickel (Ni) | 30.0 – 34.0 |
| Chromium (Cr) | 26.0 – 28.0 |
| Iron (Fe) | Balance |
| Molybdenum (Mo) | 3.0 – 4.0 |
| Copper (Cu) | 0.6 – 1.4 |
| Manganese (Mn) | ≤ 2.0 |
| Silicon (Si) | ≤ 1.0 |
| Carbon (C) | ≤ 0.03 |
| Phosphorus (P) | ≤ 0.03 |
| Sulfur (S) | ≤ 0.01 |
Physical Properties of Incoloy 28
| Property | Value |
|---|---|
| Density | 8.0 g/cm³ |
| Melting Range | 1320 – 1365°C |
| Electrical Resistivity | 0.95 μΩ·m |
| Thermal Conductivity | 12 W/m·K |
| Specific Heat Capacity | 500 J/kg·K |
| Modulus of Elasticity | 200 GPa |
Mechanical Properties of Incoloy 28
| Property | Value |
|---|---|
| Tensile Strength | ≥ 500 MPa |
| Yield Strength (0.2% Offset) | ≥ 214 MPa |
| Elongation | ≥ 35% |
| Hardness | ≤ 90 HRB |
Corrosion Resistance
Incoloy 28 is recognized for its exceptional resistance to sulfuric acid, phosphoric acid, and a wide range of chloride-containing environments. The combination of high chromium, molybdenum, and nickel contents provides outstanding protection against pitting corrosion, crevice corrosion, and stress corrosion cracking.
The alloy performs particularly well in wet-process phosphoric acid production, sulfuric acid handling systems, and offshore environments where conventional stainless steels may fail. Its low carbon content also improves resistance to sensitization and intergranular corrosion after welding.
High Temperature Performance
| Property | Performance |
|---|---|
| Recommended Continuous Service Temperature | Up to approximately 600°C |
| Oxidation Resistance | Good |
| Thermal Stability | Good |
| Sulfidation Resistance | Moderate |
Available Forms
| Product Form | Availability |
|---|---|
| Pipe | Seamless / Welded |
| Tube | Seamless / Welded |
| Plate | Available |
| Sheet | Available |
| Bar | Round / Flat / Hex |
| Rod | Available |
| Flange | Available |
| Pipe Fittings | Available |
Applications of Incoloy 28
- Chemical processing equipment
- Sulfuric acid plants
- Phosphoric acid production
- Offshore and marine systems
- Oil and gas processing equipment
- Heat exchangers
- Storage tanks and reactors
- Pollution control equipment
- Desalination plants
- Pulp and paper processing
Incoloy 28 vs Other Alloys
| Property | Incoloy 28 | 904L | 316L | Alloy 20 |
|---|---|---|---|---|
| Sulfuric Acid Resistance | Excellent | Very Good | Moderate | Excellent |
| Pitting Resistance | Excellent | Very Good | Moderate | Good |
| Chloride SCC Resistance | Excellent | Good | Poor | Excellent |
| Cost | Medium-High | Medium | Low | Medium |
Welding & Fabrication
Incoloy 28 offers excellent weldability using GTAW (TIG), GMAW (MIG), SMAW and SAW processes. The alloy can be readily formed and fabricated using conventional stainless steel fabrication equipment. Low heat input and proper post-weld cleaning are recommended to maintain optimum corrosion resistance.
Standards & Equivalent Grades
| Standard | Designation |
|---|---|
| UNS | N08028 |
| Werkstoff Number | 1.4563 |
| ASTM Pipe & Tube | B668 |
| ASTM Plate, Sheet & Strip | B709 |
| ASTM Bar & Rod | B649 |
| ASME | SB668 / SB709 / SB649 |
| Trade Name | Alloy 28 / Incoloy 28 |
Frequently Asked Questions
What is Incoloy 28 used for?
Incoloy 28 is widely used in chemical processing equipment, sulfuric acid plants, phosphoric acid production, offshore systems, heat exchangers, storage tanks, and pollution control equipment where superior corrosion resistance is required.
Is Incoloy 28 resistant to sulfuric acid?
Yes. Incoloy 28 provides excellent resistance to sulfuric acid over a wide range of concentrations and temperatures, making it suitable for chemical processing and fertilizer production facilities.
Is Incoloy 28 resistant to phosphoric acid?
Yes. Incoloy 28 is widely used in wet-process phosphoric acid production because of its excellent resistance to phosphoric acid and related corrosive process streams.
What is the difference between Incoloy 28 and 904L?
Incoloy 28 generally offers better resistance to pitting corrosion, crevice corrosion, and chloride stress corrosion cracking than 904L, particularly in highly aggressive chloride-containing environments.
What is the difference between Incoloy 28 and Alloy 20?
Both alloys offer excellent corrosion resistance, but Alloy 20 is primarily optimized for sulfuric acid service, while Incoloy 28 provides broader resistance to chlorides, phosphoric acid, and localized corrosion.
Is Incoloy 28 better than 316L stainless steel?
For highly corrosive environments, Incoloy 28 significantly outperforms 316L stainless steel in terms of pitting resistance, crevice corrosion resistance, and chloride stress corrosion cracking resistance.
Can Incoloy 28 be welded?
Yes. Incoloy 28 exhibits excellent weldability and can be welded using GTAW (TIG), GMAW (MIG), SMAW and other conventional industrial welding methods.
What is the UNS number of Incoloy 28?
The UNS designation for Incoloy 28 is UNS N08028.
What is the chemical composition of Incoloy 28?
Incoloy 28 is a nickel-iron-chromium alloy containing approximately 30–34% nickel, 26–28% chromium, and 3–4% molybdenum, with controlled additions of copper and other elements to enhance corrosion resistance.
What is the PREN value of Incoloy 28?
The Pitting Resistance Equivalent Number (PREN) of Incoloy 28 is typically around 38–40, indicating excellent resistance to pitting and crevice corrosion in chloride-containing environments.
Is Incoloy 28 suitable for sour gas service?
Yes. Incoloy 28 is frequently used in oil and gas applications involving hydrogen sulfide (H₂S), carbon dioxide (CO₂), and chloride-containing environments due to its excellent corrosion resistance.
What forms are available for Incoloy 28?
Incoloy 28 is available in pipe, tube, plate, sheet, bar, rod, flange, and fitting forms to satisfy a wide range of industrial requirements.
Which industries use Incoloy 28?
Incoloy 28 is commonly used in chemical processing, fertilizer production, phosphoric acid plants, offshore engineering, oil and gas processing, marine systems, and pollution control industries.
Why Choose J&A Alloy
J&A Alloy specializes in supplying premium nickel alloys and corrosion-resistant materials for demanding industrial applications worldwide.
We provide strict quality control, full traceability, and Mill Test Certificates (EN 10204 3.1) for every shipment.
Our global logistics network ensures timely delivery of standard and custom-sized products.
With extensive experience in nickel alloys, our technical team can assist with material selection, standards compliance, and project-specific requirements.
