Alloy 28 (also known as UNS N08028) is a high-alloy austenitic stainless steel specifically engineered for highly corrosive environments. It offers exceptional resistance to strong acids, stress corrosion cracking, and pitting corrosion, making it a preferred choice in chemical processing, oil and gas, and pharmaceutical industries.
Chemical Composition of Alloy 28
| Element |
Maximum Content (%) |
| Carbon (C) | ≤ 0.020 |
| Silicon (Si) | ≤ 0.6 |
| Manganese (Mn) | ≤ 2.0 |
| Phosphorus (P) | ≤ 0.025 |
| Sulfur (S) | ≤ 0.010 |
| Chromium (Cr) | 27 |
| Nickel (Ni) | 31 |
| Molybdenum (Mo) | 3.5 |
| Copper (Cu) | 1.0 |
Note: These chemical limits ensure Alloy 28's superior corrosion resistance and mechanical performance.
Key Properties and Benefits
- Exceptional Corrosion Resistance: Alloy 28 exhibits excellent resistance to hydrochloric acid, sulfuric acid, and other aggressive chemicals.
- High Resistance to Stress Corrosion Cracking (SCC): Suitable for environments prone to SCC, including chloride-rich solutions.
- Resistance to Pitting and Crevice Corrosion: Thanks to its high chromium, nickel, and molybdenum content.
- Good Weldability: Can be welded using standard techniques without compromising corrosion resistance.
- Durability: Maintains structural integrity in high-temperature and pressure applications.
Industry Standards and Specifications
Alloy 28 conforms to a range of international standards, ensuring its suitability for critical industrial applications:
- UNS Number: N08028
- ISO: 4563-080-28-I
- EN Number: 1.4563
- EN Name: X 1 NiCrMoCu 31-27-4
- W.Nr.: 1.4563
Product Standards
| Product Form |
Applicable Standards |
| Seamless Tube & Pipe | ASTM B668, EN 10216-5, SEW 400, SS 14 25 84, NFA 49-217 |
| Plate, Sheet, Strip | ASTM B709, EN 10088-2, SS 14 25 84 |
| Bar Steel | EN 10088-3, SS 14 25 84 |
| Fittings | ASTM A403 (per ASTM B668 chemical and mechanical specs) |
Approvals and Certifications
- ASME: Certified under Boiler and Pressure Vessel Code (Sections I, III, VIII, Division 1) – Code Case 1325-18.
- NACE MR0103 & MR0175/ISO 15156: Resistant to sulfide stress cracking in petroleum refining and oilfield environments.
- VdTÜV-Werkstoffblatt 483: Certified austenitic rolled and forged steel.
- NGS 1608: Nordic rules for application of corrosion-resistant alloys.
Applications / Uses of Alloy 28
- Chemical processing equipment (reactors, heat exchangers, piping)
- Oil and gas industry (sour gas environments, offshore platforms)
- Pharmaceutical manufacturing plants
- Pulp and paper industry
- Desalination plants
Why Choose Alloy 28?
Alloy 28 combines the best attributes of stainless steel alloys with enhanced corrosion resistance and durability. Its multi-purpose nature allows it to thrive in harsh chemical and high-temperature environments, ensuring longevity and reliability for critical infrastructure.
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