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DIN 1.4462 Stainless Steel: Duplex 2205 Grade for High Corrosion Resistance & Strength
DIN 1.4462 (UNS S32205/S31803), commonly known as 2205 duplex stainless steel, is a nitrogen-enhanced ferritic-austenitic alloy combining superior corrosion resistance with high mechanical strength. Its balanced microstructure (50% ferrite/50% austenite) delivers twice the yield strength of 316L while maintaining excellent pitting and crevice corrosion resistance (PREN ≥ 35). This grade is ideal for chemical processing, marine environments, and high-pressure applications where 300-series stainless steels fall short.
1. Chemical Composition (EN 10088-3 Standard)
| Element | Content Range | Function |
|---|---|---|
| Chromium (Cr) | 21.00 – 23.00% | Forms passive Cr₂O₃ film; primary corrosion resistance contributor |
| Nickel (Ni) | 4.50 – 6.50% | Stabilizes austenite phase; balances ferrite/austenite ratio |
| Molybdenum (Mo) | 2.50 – 3.50% | Enhances pitting/crevice corrosion resistance (PREN booster) |
| Nitrogen (N) | 0.14 – 0.20% | Strengthens austenite; improves corrosion resistance and weldability |
| Manganese (Mn) | ≤ 2.00% | Deoxidizer; partial nickel substitute for cost control |
| Silicon (Si) | ≤ 1.00% | Improves oxidation resistance; deoxidation agent |
| Carbon (C) | ≤ 0.030% | Minimized to prevent intergranular corrosion |
| Phosphorus (P) | ≤ 0.030% | Impurity; controlled to maintain toughness |
| Sulfur (S) | ≤ 0.020% | Impurity; reduced to prevent hot cracking |
2. Mechanical Properties (Room Temperature)
- Tensile Strength (Rm): 620-880 MPa (EN 10088-3)
- Yield Strength (Rp0.2): ≥ 450 MPa (2× stronger than 316L)
- Elongation (A5): ≥ 25% (excellent ductility for duplex grade)
- Hardness (HB): ≤ 290 (Brinell; work-hardens during forming)
- Impact Toughness (KV): ≥ 100 J at -46°C (superior to ferritic grades)
- PREN Value: ≥ 35 (Pitting Resistance Equivalent Number)
3. Manufacturing Process
- Melting: Electric arc furnace (EAF) + AOD (argon oxygen decarburization) with nitrogen injection to achieve precise N content (0.14-0.20%).
- Hot Working: Forged/rolled at 1100-1200°C with controlled cooling to maintain phase balance; solution annealing at 1020-1100°C followed by water quenching.
- Cold Working: Limited to 10-15% deformation per pass due to high work-hardening rate; intermediate annealing required for complex forming.
- Heat Treatment: Solution annealing at 1020-1100°C with rapid cooling to dissolve intermetallic phases (σ, χ) and restore corrosion resistance.
- Surface Finishing: Pickling in nitric-hydrofluoric acid blend to remove oxide scale; passivation with nitric acid to enhance Cr₂O₃ film stability.
4. Key Application Fields
Chemical & Petrochemical
Pressure vessels, heat exchangers, and piping systems for sulfuric acid, phosphoric acid, and chloride-containing media (e.g., desalination plants).
Oil & Gas Industry
Subsea pipelines, umbilical tubes, and topside processing equipment resistant to H₂S/CO₂ corrosion and high-pressure environments.
Marine & Offshore
Seawater cooling systems, ballast water tanks, and ship propulsion shafts with superior resistance to crevice corrosion in chloride-rich environments.
Pulp & Paper
Bleach plant equipment, digesters, and stock handling systems exposed to corrosive bleaching agents (e.g., chlorine dioxide).
Food Processing
High-pressure food sterilization equipment and brine solutions where 304/316L fail due to stress corrosion cracking (SCC) risks.
Structural Components
Bridges, architectural facades, and load-bearing structures requiring high strength-to-weight ratio and corrosion resistance in aggressive atmospheres.
5. Comparison with Other Duplex Grades
| Grade | PREN | Key Features | Typical Applications |
|---|---|---|---|
| 1.4462 (2205) | 35-40 | Balanced properties; cost-effective for most duplex applications | Chemical processing, marine equipment, pressure vessels |
| 1.4410 (2507) | 40-45 | Super duplex; higher Mo/N for extreme corrosion resistance | Offshore platforms, desalination, FGD systems |
| 1.4362 (2304) | 24-26 | Lean duplex; lower Ni/Mo for cost-sensitive applications | Structural components, water treatment, mild chemical exposure |
6. Selection & Fabrication Guidelines
- Welding: Use ER2209 filler metal; maintain interpass temperature ≤ 150°C to avoid precipitation of harmful phases. Post-weld annealing not typically required for thin sections.
- Machining: Requires rigid tooling due to high work-hardening; use carbide tools with positive rake angles and slow speeds (60-80 m/min).
- Corrosion Limits: Avoid prolonged exposure to temperatures above 300°C (risk of 475°C embrittlement) or below -50°C (reduced impact toughness).
- Surface Finish: 2B/No.1 for industrial applications; electropolished (RA ≤ 0.5 μm) for critical corrosion resistance in pharmaceutical/food contact.
- Testing: Verify phase balance (ferrite/austenite ratio) via feritscope; confirm PREN ≥ 35 for specified corrosion resistance.
7. Request a Duplex Stainless Steel Quote
Need DIN 1.4462 (2205) duplex stainless steel in sheets, plates, pipes, or custom fabricated components? Contact our team for technical specifications, mill test certificates (EN 10204 3.1/3.2), and competitive pricing tailored to your project requirements.
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