Super Duplex A182 F55 Corrosion Resistant Welding Neck Flange for High Pressure Environments
SUPER DUPLEX A182 F55 is a super duplex stainless steel grade primarily used for flanges, fittings, and forged components in highly corrosive and high-pressure environments. Its applications include offshore operations, oil & gas facilities, desalination plants, and chemical processing plants. The material's exceptional strength and corrosion resistance are derived from its precisely balanced chemical composition.
The following table presents the typical chemical composition ranges for ASTM A182 F55 / UNS S32760 (Super Duplex F55). Exact values may vary slightly by manufacturer, but these ranges represent standard specifications:
| Element | Composition Range | Function & Benefits |
|---|---|---|
| Carbon (C) | max 0.03% | Low carbon content prevents carbide precipitation and maintains corrosion resistance |
| Chromium (Cr) | 24.0 – 26.0% | Provides general corrosion resistance and forms a stable passive film |
| Nickel (Ni) | 6.0 – 8.0% | Stabilizes the austenitic phase and improves toughness and stress corrosion cracking resistance |
| Molybdenum (Mo) | 3.0 – 4.0% | Significantly enhances resistance to pitting and crevice corrosion in chloride-containing environments |
| Tungsten (W) | 0.5 – 1.0% | Further improves pitting and crevice corrosion resistance in aggressive chloride conditions |
| Copper (Cu) | 0.5 – 1.0% | Enhances resistance to certain non-oxidizing acids like sulfuric acid environments |
| Manganese (Mn) | max 1.00% | Used for deoxidation and steelmaking processes |
| Silicon (Si) | max 1.00% | Used for deoxidation; controlled to prevent toughness reduction |
| Nitrogen (N) | 0.20 – 0.30% | Key strengthening element that increases yield strength and improves pitting/crevice corrosion resistance |
| Phosphorus (P) | max 0.030% | Impurity restricted to maintain toughness and corrosion resistance |
| Sulfur (S) | max 0.010% | Impurity restricted to maintain toughness and corrosion resistance |
| Iron (Fe) | Balance | Base element comprising the remainder of the composition |
- Chromium: ~25%, Nickel: ~7%, Molybdenum: ~3.5%, Nitrogen: ~0.25%
- Additional Tungsten and Copper for enhanced corrosion resistance
- Very low Carbon, Phosphorus, and Sulfur content to preserve toughness and weldability
For project-specific requirements, always consult:
- The relevant ASTM standard (ASTM A182 for forged fittings/flanges)
- The mill test certificate (MTC) from your material supplier, which provides precise heat analysis for the specific batch being used
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