1. Specifications & Capability
FUSHUN METAL forges duplex and super duplex stainless components in F51 (S31803/2205, 1.4462) and F53 (S32750/2507, 1.4410), solution annealed and compliant with NACE MR0175 for sour service. These are the valve bodies, fittings and flanges of offshore and sour oil and gas fields.
The duplex microstructure – roughly equal parts austenite and ferrite – combines the strength of ferrite with the corrosion resistance of austenite, giving roughly twice the yield strength of a standard austenitic stainless.
| Grade | Standard | Type |
|---|---|---|
| F51 / 2205 / 1.4462 | ASTM A182 | Duplex stainless |
| F53 / 2507 / 1.4410 | ASTM A182 | Super duplex stainless |
2. Components & Service Conditions
These forgings are the valve bodies, fittings and flanges of offshore platforms and sour oil and gas fields, where the service combines chloride-bearing seawater or brine with hydrogen sulfide. Under these conditions ordinary stainless steels suffer pitting and chloride stress-corrosion cracking, and carbon steels fail by sulfide stress cracking.
The duplex grades resist both mechanisms: the ferrite gives resistance to chloride stress-corrosion cracking, and the chromium, molybdenum and nitrogen give pitting resistance – the super duplex F53, with higher chromium, molybdenum and nitrogen, is specified for the most aggressive sour and chloride environments. Solution annealing develops the correct austenite-ferrite balance, and corrosion testing confirms resistance to the service medium.
3. Grade Equivalents – F51 (2205) / F53 (2507)
| Designation | Standard | Notes |
|---|---|---|
| F51 / S31803 / 2205 / 1.4462 | ASTM A182 | Standard duplex |
| F53 / S32750 / 2507 / 1.4410 | ASTM A182 | Super duplex |
| S32205 / 2205 | ASTM A182 | Higher-nitrogen duplex variant |
| 00Cr22Ni5Mo3N | GB/T 1220 | Reference only, not used in certification |
| Grade | C | Cr | Ni | Mo | N |
|---|---|---|---|---|---|
| F51 (2205) | 0.030 max | 21.0-23.0 | 4.5-6.5 | 2.5-3.5 | 0.08-0.20 |
| F53 (2507) | 0.030 max | 24.0-26.0 | 6.0-8.0 | 3.0-5.0 | 0.24-0.32 |
The higher chromium, molybdenum and nitrogen of the super duplex F53 give superior pitting resistance, measured by a higher pitting resistance equivalent number.
4. Manufacturing Process
Melting. FUSHUN METAL melts to tight chemistry limits, keeping carbon low and controlling nitrogen, which stabilises the austenite.
Forging. Components are forged with controlled deformation and temperature to develop the correct austenite-ferrite balance.
Solution annealing. The forging is solution annealed and quenched to set the duplex structure and restore corrosion resistance.
Testing. UT, ferrite measurement, mechanical and corrosion tests to NACE MR0175, with full traceability.
5. Standards & Certification
Duplex forgings are supplied to ASTM A182 and compliant with NACE MR0175 / ISO 15156 for sour service, with inspection certificates under EN 10204 3.1. FUSHUN METAL holds ISO 9001 and AS9120B certification.
Related forging: low-temperature forgings.
6. Typical Applications
Offshore platforms
Valve bodies and fittings for offshore topsides.
Sour oil and gas
NACE-compliant forgings for sour service.
Seawater systems
Forgings for seawater and brine handling.
Subsea equipment
Super duplex forgings for subsea manifolds and trees.
7. Inquiry Essentials
To quote your duplex forging, please provide the component drawing, the service medium, and the required grade (F51 or F53).
