Why Duplex Stainless Steel Excels at Corrosion Resistance？

1. Dual-Phase Microstructure Enhances Protection

• ~50% Austenite (γ-phase) – Provides toughness and chloride stress corrosion cracking (SCC) resistance.
• ~50% Ferrite (α-phase) – Adds strength and resistance to pitting/crevice corrosion.
• Synergistic effect – The two phases work together to block crack propagation and slow corrosion rates.

2. High Chromium & Molybdenum Content

• 22-25% Chromium (Cr) – Forms a robust passive oxide layer that self-repairs in oxidizing environments.
• 3-4% Molybdenum (Mo) – Dramatically improves resistance to pitting in chlorides, acids, and seawater.
• 5-7% Nickel (Ni) – Stabilizes the austenitic phase while enhancing ductility.

3. Nitrogen Alloying for Extra Defense

• 0.2-0.3% Nitrogen (N) – Increases pitting resistance equivalent number (PREN > 35).
• Strengthens the passive film and improves resistance to chloride-induced corrosion.

4. Superior Performance in Key Corrosion Types

• Pitting & Crevice Corrosion – Outperforms 316L and 304L in saltwater and acidic conditions.
• Stress Corrosion Cracking (SCC) – More resistant than austenitic grades in chloride-rich environments.
• General Corrosion – Holds up well in sulfuric acid, phosphoric acid, and organic acids.

5. Real-World Applications

• Oil & Gas – Subsea pipelines, risers, and pressure vessels.
• Desalination Plants – Heat exchangers and brine handling.
• Chemical Processing – Reactors, tanks, and piping.
• Marine Engineering – Propeller shafts and seawater cooling systems.