2205 Duplex Steel Round Bar (UNS S31803/S32205) is a premium-grade stainless steel material renowned for its unique microstructure, combining austenitic and ferritic phases to deliver exceptional strength, corrosion resistance, and durability. This duplex alloy features a balanced composition of chromium (21.0–23.0%), nickel (4.5–6.5%), molybdenum (2.5–3.5%), and nitrogen, creating a microstructure that offers twice the yield strength of conventional austenitic steels like 304 or 316.
Manufactured to standards including ASTM A276 and EN 10088-3, Duplex 2205 round bars undergo precision cold drawing or bright finishing to ensure uniform dimensional accuracy, superior surface finish, and consistent mechanical properties. The alloy’s dual-phase structure makes it ideal for demanding applications where high strength and resistance to chloride-induced stress corrosion cracking (SCC) are critical.
Zhejiang Xintongda Special Steel Manufacturing Co., Ltd. delivers Duplex 2205 round bars that meet the highest quality benchmarks, offering reliable solutions for industries ranging from offshore oil and gas to chemical processing.
| Grade | C | Mn | Si | P | S | Cr | Mo | Ni | N |
| 2205 (S31803) | ≤0.03 | ≤2.0 | ≤1.0 | ≤0.030 | ≤0.020 | 21.0–23.0 | 2.5–3.5 | 4.5–6.5 | 0.08–0.20 |
| 2205 (S32205) | ≤0.03 | ≤2.0 | ≤1.0 | ≤0.030 | ≤0.020 | 21.0–23.0 | 3.0–3.5 | 4.5–6.5 | 0.14–0.20 |
| Property | Value |
| Tensile Strength | 650–880 MPa |
| Yield Strength (0.2% offset) | ≥450 MPa |
| Elongation | ≥25% |
| Hardness (HB) | ≤270 HB |
| Elastic Modulus | 200 GPa |
| Property | Value |
| Density | 7.805 g/cm³ |
| Thermal Conductivity | 19.0 W/m·K |
| Thermal Expansion | 13.7×10⁻⁶/K |
| Electrical Resistivity | 0.85×10⁻⁶ Ω·m |
| Melting Point | 1400–1450°C |
| Parameter | Duplex 2205 (S31803) | Austenitic 316L (S31603) | Super Duplex 2507 (S32750) |
| Microstructure | Austenitic-ferritic | Fully austenitic | Austenitic-ferritic |
| Yield Strength | ≥450 MPa | ≥170 MPa | ≥550 MPa |
| Cr Content | 21–23% | 16–18% | 24–26% |
| Mo Content | 2.5–3.5% | 2.0–3.0% | 3.0–5.0% |
| N Content | 0.08–0.20% | – | 0.24–0.32% |
| Chloride SCC Resistance | Good | Moderate | Excellent |
| Service Temperature | -40°C to 250°C | -196°C to 800°C | -50°C to 300°C |
| Typical Applications | Offshore, chemical | General corrosion | Extreme marine, oil & gas |
Key Insights:
Duplex 2205 offers 2.5x the yield strength of 316L, reducing material thickness and weight.
Super Duplex 2507 outperforms 2205 in severe chloride environments but at higher cost.
Chloride Stress Corrosion Cracking (SCC): Resists SCC in seawater, brine, and chloride-rich media, making it ideal for offshore and marine applications.
Pitting & Crevice Corrosion: High chromium, molybdenum, and nitrogen content provide superior resistance to localized corrosion compared to austenitic steels.
Acid & Alkali Resistance: Performs well in mild acids (e.g., sulfuric, phosphoric) and alkaline solutions, suitable for chemical processing.
Mechanical Advantage: With yield strength ≥450 MPa, Duplex 2205 allows for lighter component designs while maintaining structural integrity.
Toughness: Retains ductility at low temperatures, preventing brittleness in cryogenic applications.
Weight Savings: Higher strength enables thinner sections, reducing material and transportation costs.
Longevity: Reduced maintenance and replacement needs due to superior corrosion resistance.
Weldability: Can be welded by TIG, MIG, and stick welding methods with proper filler metals (e.g., ER2209).
Machinability: Requires slightly slower speeds than austenitic steels but offers good formability and cutting performance.
Subsea Equipment: Pipelines, valves, and wellheads exposed to seawater and corrosive hydrocarbons.
Platform Structures: Support beams and components in marine environments.
Reactors & Vessels: Handling acids, chlorides, and other corrosive chemicals.
Heat Exchangers: Efficient heat transfer with resistance to fouling and corrosion.
Desalination Plants: Heat exchangers and pipes in seawater treatment systems.
Shipbuilding: Propulsion systems, hull components, and seawater piping.
Flue Gas Desulfurization (FGD): Scrubbers and ducts in coal-fired power plants.
Geothermal Energy: Tubing for high-temperature, acidic geothermal fluids.
Duplex 2205 offers twice the yield strength of 316L, making it lighter and more cost-effective for high-stress applications. It also provides superior resistance to chloride SCC, which 316L lacks in severe environments.
Yes, Duplex 2205 resists chloride SCC in seawater up to 250°C. For higher temperatures or more aggressive chlorides, Super Duplex 2507 is recommended.
Nitrogen Content: S32205 has higher nitrogen (0.14–0.20%) for enhanced strength and corrosion resistance.
Mo Content: S32205 contains 3.0–3.5% molybdenum (vs. 2.5–3.5% in S31803), improving pitting resistance.
Yes, due to its ferritic phase, Duplex 2205 is slightly magnetic, unlike fully austenitic steels like 316L.
Use ER2209 filler metal and control heat input to avoid excessive ferrite formation. Post-weld annealing is rarely needed but can improve ductility for critical parts.
Duplex 2205 performs reliably from -40°C to 250°C. Beyond 250°C, its microstructure may degrade, reducing corrosion resistance.
Standard pickling or passivation is sufficient for most applications. Polishing can be applied for aesthetic purposes or to minimize crevice corrosion.
