| Customization: | Available |
|---|---|
| Application: | Chemical Industry, Oil and Gas Industry, Seawater & Oil Pipeline |
| Certification: | CE, ISO9001 |
|
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| Property | UNS S31803 | UNS S32205 |
| Microstructure | Dual-phase (50% austenite, 50% ferrite) | Optimized dual-phase balance for enhanced performance. |
| PREN<sup>*</sup> | ~34-36 | ~35-38 |
| Strength | High yield strength (450-550 MPa) | Higher yield strength (≥550 MPa) |
| Corrosion Resistance | Excellent resistance to chloride stress corrosion cracking (SCC) and pitting. | Superior resistance to localized corrosion (e.g., crevice, pitting). |
| Element | UNS S31803 | UNS S32205 | Role |
|---|---|---|---|
| Cr | 21.0-23.0 | 22.0-23.0 | Corrosion resistance. |
| Ni | 4.5-6.5 | 4.5-6.5 | Stabilizes austenite phase. |
| Mo | 2.5-3.5 | 3.0-3.5 | Enhances pitting resistance. |
| N | 0.08-0.20 | 0.14-0.20 | Strengthens matrix, improves PREN. |
| Mn | ≤2.0 | ≤2.0 | Austenite stabilizer. |
| C | ≤0.030 | ≤0.030 | Prevents carbide precipitation. |
Key Difference: S32205 has tighter control on Mo and N, improving PREN and corrosion performance.
| Property | UNS S31803 | UNS S32205 |
|---|---|---|
| Yield Strength | ≥450 MPa | ≥550 MPa |
| Tensile Strength | ≥620 MPa | ≥690 MPa |
| Elongation | ≥25% | ≥25% |
| Hardness (HV) | ≤290 | ≤310 |
Chloride Environments: Resistant to SCC in seawater, brine, and chloride-rich media.
Acidic Media: Performs well in dilute sulfuric acid, acetic acid, and phosphoric acid.
Sour Service: Compliant with NACE MR0175/ISO 15156 for H<sub>2</sub>S-containing environments (limited partial pressure).
S32205 Advantage: Higher PREN (~38) ensures better resistance to pitting in high-chloride or acidic conditions.
Oil & Gas: Subsea pipelines, downhole tubing, manifolds.
Chemical Processing: Heat exchangers, reactors, acid handling systems.
Desalination: Seawater reverse osmosis (SWRO) systems.
Pulp & Paper: Bleaching equipment.
Pipe Production:
Hot extrusion or cold drawing for seamless pipes.
Welded pipes use TIG, laser, or plasma welding.
Heat Treatment: Solution annealing at 1020-1100°C, followed by rapid quenching to maintain phase balance.
Welding Tips:
Use duplex-grade filler metals (e.g., ER2209).
Avoid prolonged heat input to prevent sigma phase formation.
| Standard | Coverage |
|---|---|
| ASTM A790/A928 | Seamless/welded duplex stainless pipes. |
| ASME B31.3 | Process piping design guidelines. |
| NORSOK M-630 | Material requirements for offshore use. |
S31803: Cost-effective for moderate chloride environments.
S32205: Preferred for critical applications (higher PREN, strength, and compliance with modern standards).
Sigma Phase Formation: Risk at 600-900°C; controlled via heat treatment.
Welding Complexity: Requires precise parameters to avoid ferrite-austenite imbalance.
UNS S32205 is the upgraded version of S31803, offering superior corrosion resistance and mechanical strength for demanding applications. While S31803 remains viable for less aggressive conditions, S32205 is increasingly favored in offshore, chemical, and energy sectors.
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