X2CrNiMoN22-5-3
Duplex stainless steel with a roughly half-austenite, half-ferrite structure. Twice the proof strength of 316L and markedly superior chloride resistance; the standard duplex grade in seawater, petrochemical and paper industries.
- Rp0.2 · MPa
- ≥ 460
- Rm · MPa
- ≥ 640
- TEMPERATURE
- ≤ +300 °C
- COST
Chemical composition
The values in this section are being verified.
Mechanical properties
| STANDARD · CONDITION | Rp0.2 MPa | Rp1.0 MPa | Rm MPa | A % | KV J |
|---|---|---|---|---|---|
| EN 10088-2 · hot-rolled plate (P) | 460 | — | ≥ 640 | 25 | 60 |
| EN 10088-3 · bar, t ≤ 160 mm | 450 | — | 650–880 | 25 | — |
| ASTM A240 · S32205 | 450 | — | ≥ 655 | 25 | — |
Minimum Rp0.2 at elevated temperature
| EN · TEMPERATURE | 20 °C | 100 °C | 200 °C |
|---|---|---|---|
| Rp0.2 MPa | 460 | 360 | 315 |
EN 10028-7 / EN 10088 values; the minimum proof strength used in pressure equipment design.
Service temperature
The duplex structure is not used for long periods above ~300 °C (475 °C embrittlement). Toughness drops at low temperature because of the ferrite.
This is the limit of the material itself. A valve's service temperature is usually set by the seal and seat materials; product pages give it for each seal option.
Physical properties and heat treatment
- DENSITY
- 7.8 kg/dm³
- MODULUS OF ELASTICITY (20 °C)
- 200 GPa
- THERMAL EXPANSION (20–100 °C)
- 13.0 × 10⁻⁶ /K
- THERMAL CONDUCTIVITY (20 °C)
- 15 W/m·K
- SPECIFIC HEAT (20 °C)
- 500 J/kg·K
- ELECTRICAL RESISTIVITY
- 0.80 µΩ·m
- MAGNETISM
- magnetic
- CRITICAL PITTING TEMPERATURE, CPT (TYPICAL)
- 52 ± 3 °C
- HEAT TREATMENT
- Solution annealing 1060 ± 40 °C, rapid cooling.
Media suitability GENERAL TREND
Emsal assessment. The final choice is made from corrosion tables, taking concentration, temperature, chloride content and flow velocity into account.
Strengths and weaknesses
Strengths
- Twice the proof strength of 316L: thinner walls, lighter body
- Highly resistant to chloride stress corrosion cracking
- CPT ≈ 52 °C: markedly superior to 316L in seawater
- High wear and erosion resistance
Weaknesses
- Not used above ~300 °C (475 °C embrittlement)
- Welding heat input and ferrite content need control
- Limited toughness at low temperature
- Harder to machine than 316L
Manufacturing and use
- ECONOMY
- Medium to high; price per kilogram close to 316L, and the higher strength means less material is used.
- MANUFACTURING METHODS
- Machining from plate and bar · Forging (ASTM A182 F51) · Cast counterpart 1.4470 (4A)
- TYPICAL VALVE PARTS
- Body · Stem (high strength) · Disc · Bolt
Used in 2 Emsal products
- 001Wafer check valveBody · Disc
- 005Short pattern swing check valveDisc
Source: EN 10088-2 / -3. Values compiled and verified by Emsal Vana; for binding values, refer to the current edition of the standard and the material certificate.