Super Duplex Stainless Steels
Super Duplex stainless steels are advanced alloys that combine austenitic and ferritic microstructures. This dual-phase composition delivers outstanding strength, toughness and corrosion resistance, making them ideal for demanding environments.
What Makes Super Duplex Different?
Compared to standard duplex grades, which typically contain around 22% chromium, Super Duplex grades increase chromium content to approximately 25%. This enhancement significantly improves corrosion resistance, especially in aggressive or chloride-rich conditions.
Super Duplex steels also contain elevated levels of molybdenum and nitrogen, contributing to a Pitting Resistance Equivalent Number (PREN) above 40. This places them ahead of most 300-series austenitic stainless steels and close to the performance of some nickel-based alloys.
Key Benefits
- High Strength: Up to twice the yield strength of conventional austenitic or ferritic stainless steels.
- Excellent Toughness and Ductility: Balanced mechanical properties across a wide temperature range.
- Superior Corrosion Resistance: Exceptional resistance to pitting, crevice corrosion and stress corrosion cracking.
- Cost Efficiency: Lower nickel content helps reduce exposure to price volatility.
- Weight Reduction: High strength allows for lighter, more compact component designs.
Enhanced Performance with Copper
Some Super Duplex grades include copper additions, which further improve corrosion resistance in environments not fully addressed by PREN. Copper helps inhibit pitting and provides excellent resistance to sulphuric acid, as well as good resistance to nitric and phosphoric acids.
Ferralium® stands out with a uniquely high copper content, offering enhanced performance in chemical processing applications and environments involving strong acids.
Applications
Super Duplex stainless steels are widely used across industries where strength and corrosion resistance are critical. Common sectors include:
- Oil and Gas
- Chemical Processing
- Desalination
- Marine and Offshore
Typical applications include:
- Pump and valve components
- Heat exchangers
- Pressure vessels
- Fasteners
- Subsea manifolds
- Shafts, couplings and instrumentation housings exposed to seawater or aggressive fluids
Why Choose Super Duplex?
Whether you’re designing for offshore platforms, chemical plants or marine equipment, Super Duplex stainless steels offer a cost-effective and high-performance solution. Their mechanical strength and corrosion resistance help extend service life, reduce maintenance and improve overall system efficiency.
