Duplex & Super Duplex Stainless Steel Forgings for Oil & Gas, Chemical & Desalination
Shivam Forge manufactures precision hot-forged duplex and super duplex stainless steel components — flanges, valve bodies, pump bodies, pipe fittings, hubs and custom forgings — in Duplex 2205 (UNS S31803/S32205, ASTM A182 F51), Super Duplex 2507 (UNS S32750, F53) and Lean Duplex 2304 (S32304, F60) at our Shapar GIDC facility in Rajkot, Gujarat.
Duplex stainless steel forgings are not simply 'stainless forgings with tighter chemistry.' The dual austenite-ferrite microstructure that gives 2205 and 2507 their combination of strength and corrosion resistance is destroyed if forging temperature, reduction ratio or post-forge solution annealing are not controlled within tight limits. Sigma phase, chi phase and secondary austenite precipitation — all of which reduce corrosion resistance and toughness — occur in duplex steels within specific temperature ranges that must be deliberately avoided. Shivam Forge has process procedures and metallurgical testing capability to manufacture duplex forgings that meet ASTM A182, NACE MR0175 and client-specific corrosion testing requirements.
The most widely used duplex grade. PREN 32–38, tensile strength ≥620 MPa, yield strength ≥450 MPa per ASTM A182. Forging window 1050–1200°C; solution anneal 1020–1100°C water quench mandatory after forging. Used for offshore subsea flanges, chemical plant piping flanges, heat exchanger end plates and valve bodies in chloride-containing environments.
PREN >40, 25% Cr, 4% Mo, 7% Ni. The highest corrosion resistance available in duplex grades. Yield strength ≥550 MPa. Forging window narrows to 1050–1150°C for 2507 — temperature excursions above 1200°C cause rapid sigma phase formation and must be strictly avoided. Used for seawater-handling equipment, desalination plant high-pressure flanges and subsea pipeline fittings.
2304 contains no molybdenum, making it the lowest-cost duplex option. PREN 22–26, yield strength ≥400 MPa. Suitable for mildly corrosive chloride environments such as pulp and paper digesters, fresh water handling and structural applications where duplex's higher strength versus austenitic is the primary driver. Forging window 1050–1200°C.
For the most aggressive subsea and chemical plant environments, we can forge Zeron 100 (UNS S32760, PREN >40, 25Cr-7Ni-3.5Mo-0.7W-0.2N) and similar hyper duplex grades. These require even tighter forging temperature control (1050–1120°C) and must be tested per ASTM A923 Method A, B and C for intermetallic phase detection.
We manufacture ASME B16.5 Class 150–2500 flanges in F51 and F53, subsea connector hubs, valve bodies (gate, globe, ball, check) and manifold bodies. All duplex flanges and valve bodies are solution annealed and water quenched, then tested per ASTM A923 sensitization testing methodology.
Pump impeller blanks, agitator shaft flanges, heat exchanger tube sheet blanks and pipe tee/elbow forgings in 2205 and 2507 for sulphuric acid, phosphoric acid, seawater desalination (RO membrane housings) and pulp & paper bleaching environments. Ferrite content 35–55% verified by magnetic balance and eddy current instruments on finished forgings.
Duplex stainless steels must be forged in the 1050–1200°C window. Below 1050°C, the ferrite phase becomes too hard and hot tears initiate. Above 1200°C, sigma and chi phase precipitate at grain boundaries during slow cooling from finish forging temperature. We use calibrated billet furnaces with ±10°C uniformity and thermocouple-verified forging temperatures.
Post-forge solution annealing at 1020–1100°C followed by immediate water quench is mandatory for all duplex forgings to dissolve any intermetallic phases formed during cooling from forging temperature. Solution anneal temperature is verified by thermocouple in the furnace charge; quench delay from furnace exit to water entry must not exceed 30 seconds for wall sections above 50 mm.
Target ferrite content in duplex 2205 forgings is 35–55% by volume. Below 35%, the material loses its stress corrosion cracking resistance advantage over austenitic grades. Above 55%, toughness and weldability deteriorate. We verify ferrite content on finished forgings using magnetic balance (Fischer Feritscope) and cross-check with point-count metallographic method per ASTM E562.
ASTM A923 (Methods A, B and C) tests for detrimental intermetallic phases in duplex stainless forgings. Method A is the copper sulphate sodium chloride etch test for sigma phase; Method B is the Charpy impact test at -46°C (minimum 54 J average for F51); Method C is the corrosion test (ASTM G48 Method A, 24h at 22°C for 2205, 40°C for 2507). We perform A923 on all production lots of critical duplex forgings.
ASTM A182 F51 requires minimum Charpy impact toughness of 54 J average (38 J minimum single) at -46°C. F53 requires 68 J average. We test at NABL-accredited labs; test results are included in the material test report. Impact toughness is sensitive to ferrite content, solution anneal temperature and sensitisation — a failed impact test is investigated by microstructural examination before retest.
Duplex steel forgings fail when manufacturers treat them like standard stainless steel. The forging temperature control, mandatory post-forge solution annealing, ferrite measurement and ASTM A923 testing are non-negotiable steps that Shivam Forge builds into every duplex production order — not as premium add-ons but as standard procedure.
Our duplex forgings are produced per ASTM A182 (flanges and fittings), ASTM A965 (large diameter flanges) and ASTM A745 (austenitic forgings framework used as reference). NACE MR0175/ISO 15156 hardness requirements (maximum 28 HRC for sour service) are met and documented. PED (Pressure Equipment Directive) CE marking available for export to EU.
Every duplex forging shipment includes EN10204 3.1 material test reports signed by our quality manager, covering: chemical analysis (OES spectrometer), mechanical properties (UTS, 0.2% proof stress, elongation, Charpy impact at -46°C), ferrite content, ASTM A923 test results and dimensional inspection.
For super duplex 2507 (F53) forgings, we calculate and report PREN (Pitting Resistance Equivalent Number = %Cr + 3.3×%Mo + 16×%N) from the spectrometric analysis of each heat. Minimum PREN >40 is required for 2507 per NORSOK M-650. Heats with PREN <40 are rejected regardless of all other test results.
We supply duplex flanges and valve body forgings to oil & gas equipment manufacturers in India and export to end-users in the North Sea, Middle East and West Africa. Subsea applications require documentation packages that include WPS/PQR weld procedure records for any repair welds, RT/UT records and pressure test certificates — all available from our quality system.
European duplex forgings carry a significant cost premium driven by labour rates and overhead. Shivam Forge produces duplex forgings at Indian labour rates with the same material specifications, testing regimes and documentation standards. Cost savings of 35–50% versus European-sourced duplex forgings are typical for flanges, valve bodies and custom shapes.
Shivam Forge is a duplex stainless steel forging manufacturer at Shapar GIDC, Rajkot, Gujarat, producing hot-forged components in Duplex 2205 (UNS S31803/S32205, ASTM A182 F51), Super Duplex 2507 (UNS S32750, F53) and Lean Duplex 2304 (S32304, F60). Our duplex forging products include ASME B16.5 flanges (Class 150–2500), valve bodies, pump body blanks, heat exchanger end plates, subsea connector hubs and custom shapes. All duplex forgings are solution annealed and water quenched in-house, with ferrite content verified to 35–55% and Charpy impact tested at -46°C per ASTM A182 requirements.
The single most common source of rejected duplex forging batches is inadequate post-forge solution annealing. When a forging cools slowly from the 1050–1200°C forging temperature window, sigma phase and chi phase nucleate at austenite-ferrite interfaces. These intermetallic phases are rich in chromium and molybdenum — the elements that provide corrosion resistance — creating chromium-depleted zones that corrode preferentially in chloride environments. The fix is immediate water quench from solution anneal temperature (1020–1100°C), fast enough to suppress intermetallic precipitation. At Shivam Forge, our post-forge solution anneal procedure specifies a maximum 30-second delay from furnace exit to water entry for sections above 50 mm wall thickness.
Ferrite content control in duplex forgings is a two-sided problem. Too little ferrite (below 35%) and the stress corrosion cracking resistance advantage of duplex over standard austenitic grades disappears. Too much ferrite (above 55%) and the Charpy impact toughness drops, weldability deteriorates and the hydrogen embrittlement susceptibility in sour service increases. Our production process targets 40–50% ferrite for 2205 (F51) forgings, verified by Fischer Feritscope on the finished forging OD and bore surfaces, cross-checked by metallographic point count per ASTM E562 on the first piece of each heat treatment batch.
Super duplex 2507 (F53) forgings demand even more precise process control than standard 2205. The 4% molybdenum and 0.3% nitrogen in 2507 significantly accelerate sigma phase kinetics — sigma can form in 2507 in minutes at temperatures between 700–1000°C, versus hours in 2205. This means 2507 forgings must be transferred from the forge to the solution anneal furnace and water quenched faster than 2205. We control reheating between forging passes to stay within the 1050–1150°C window for 2507, and our solution anneal furnace is pre-set and verified at temperature before 2507 forgings are discharged from the forge press. PREN is calculated from each heat's spectrometric analysis; batches below PREN 40 are rejected.
Shivam Forge exports duplex and super duplex forgings to oil & gas equipment manufacturers, chemical plant contractors and desalination plant builders in 12+ countries. Our documentation package for duplex forgings includes EN10204 3.1 material test reports (chemical analysis, mechanical properties, Charpy at -46°C, ferrite content), ASTM A923 sensitisation test reports (Methods A, B and C), dimensional inspection reports and NACE MR0175 hardness compliance records. To discuss your duplex forging requirement — flanges, valve bodies, custom shapes — contact us at +91 92657 72827 or email sales@shivamforge.com.
We forge Duplex 2205 (UNS S31803/S32205, ASTM A182 F51), Super Duplex 2507 (UNS S32750, F53), Lean Duplex 2304 (S32304, F60) and Zeron 100/Hyper Duplex. We also forge duplex in ASME flanges (Class 150–2500) and custom valve body, pump body and hub configurations.
Duplex 2205 forging price depends on the finished weight, complexity and machining scope. As a guide, ASME B16.5 Class 300 flanges in F51 (2205) range from ₹800–2,500 per kg of finished forging weight for production quantities. Super duplex 2507 (F53) is priced higher due to raw material cost. Contact +91 92657 72827 or sales@shivamforge.com for a specific quotation with material certification.
Shivam Forge at Shapar GIDC, Rajkot is a certified duplex stainless steel forging manufacturer in India with ISO 9001:2015 certification and experience supplying F51 and F53 forgings to oil & gas, chemical plant and desalination equipment manufacturers. We produce forgings per ASTM A182, with ASTM A923 sensitisation testing and Charpy impact at -46°C.
Yes. Solution annealing at 1020–1100°C followed by immediate water quench is mandatory for all duplex forgings at Shivam Forge and is included in the standard scope. We verify solution anneal temperature by thermocouple, control quench delay to <30 seconds for heavy sections, and test post-anneal ferrite content (target 35–55%) on finished forgings.
Yes. ASTM A923 Method A (copper sulphate etch), Method B (Charpy impact at -46°C) and Method C (ASTM G48 Method A corrosion test) can be performed and reported for duplex 2205 (F51) and super duplex 2507 (F53) forgings. Test reports are issued by NABL-accredited labs and included in the material certificate package.
PREN (Pitting Resistance Equivalent Number = %Cr + 3.3×%Mo + 16×%N) quantifies the resistance to pitting corrosion in chloride environments. Super duplex 2507 (F53) must have PREN >40 per NORSOK M-650 for subsea and seawater applications. We calculate and report PREN from spectrometric analysis of every heat, and reject heats with PREN <40.
Yes. We manufacture ASME B16.5 Class 150–2500 weld neck, slip-on, blind and special flanges in F51 and F53 for offshore topside and subsea applications. Full 3.1 material certificates, ASTM A923 test reports, Charpy impact records and dimensional inspection reports are provided with every shipment.
Email your drawing with material specification (UNS number or ASTM A182 grade), forging weight, required testing (A923, NACE hardness, ferrite content) and delivery requirement to sales@shivamforge.com or call +91 92657 72827. We will respond with a detailed quotation and material test record template within 24 hours.
Why Choose Shivam Forge
Shivam Forge delivers precision hot-forged components from our integrated Shapar, Rajkot facility — covering forging, CNC machining, heat treatment, and quality inspection under one roof.
