Super Duplex 2507 Stainless Steel Coils

Exceptional Pitting and Crevice Corrosion Resistance: PRE ≥ 42 (typically 42–45) due to high chromium (24–26%), high molybdenum (3.0–5.0%), and nitrogen (0.24–0.32%) content.

Ultra-High Mechanical Strength: Minimum yield strength ≥ 550 MPa (approximately 3.2 times that of 316L and 1.2 times that of Duplex 2205).

Superior Chloride SCC Resistance: Excellent resistance to chloride-induced stress corrosion cracking, significantly outperforming both austenitic grades and standard duplex 2205.

NACE MR0175 / ISO 15156 Compliant: Fully qualified for sour service with highest allowable H₂S partial pressures and lowest pH values.

Excellent Low-Temperature Toughness: Maintains excellent impact toughness down to -50°C with Charpy V-Notch ≥ 70J typical at -46°C.

Low Thermal Expansion: Coefficient of thermal expansion (13.0 μm/m·K) – lowest among all duplex and austenitic grades.

High Resistance to Erosion and Corrosion Fatigue: Outstanding resistance to high-velocity seawater and abrasive slurry applications.

Good Weldability: Requires strict procedure with low heat input, N₂ shielding gas, and ER2594 filler metal.

International Certifications: Coils can be certified by ABS, BV, DNV, LR, GL, RINA, CCS, KR, and NK, and comply with NORSOK M-630, NACE MR0175, and ISO 13628-4 standards.

Super Duplex 2507 (S32750) contains higher chromium, molybdenum, and nitrogen compared to Duplex 2205, resulting in a PRE value of ≥42 (compared to ≤35 for 2205). The high nitrogen content promotes austenite stability, significantly increases pitting resistance, and enhances mechanical strength. PREN = %Cr + 3.3 × %Mo + 16 × %N ≥ 42 (typically 42–45).

Comparison of PRE (Pitting Resistance Equivalent) Values:

High-Temperature Tensile Properties (Typical Values):

Impact Toughness (Charpy V-Notch, typical at -46°C):

l   Longitudinal: ≥ 70 J (typical)

l   Transverse: ≥ 50 J (typical)

Comparison of Strength (Super Duplex 2507 vs Other Grades):

Maximum Recommended Service Temperatures:

Critical Note: Super Duplex 2507 is not recommended for prolonged service above 300°C due to the risk of embrittling intermetallic phase precipitation (sigma phase). For structural applications above 300°C, austenitic grades (321/347/310S) should be considered.

Heat Treatment Condition:
Super Duplex 2507 stainless steel coils are solution annealed at 1050–1120°C followed by immediate water quenching (delay must be kept under 30 seconds). This heat treatment restores the balanced 40–60% ferrite / 40–60% austenite microstructure, dissolves unwanted intermetallic phases (sigma, chi) that form readily in super duplex grades, relieves internal stresses from rolling, and ensures maximum corrosion resistance.

Critical Note: Super Duplex 2507 requires immediate water quenching after solution annealing. Air cooling is completely unacceptable and will result in intermetallic phase precipitation, severely reducing corrosion resistance and toughness. The quenching delay must be kept under 30 seconds after opening the furnace.

Delivery Condition:
Coils are normally supplied in solution annealed and pickled condition, providing a clean, smooth surface and excellent corrosion resistance. Pickling removes the oxide scale formed during heat treatment and restores the passive surface. Bright annealing is not recommended for super duplex grades due to the water quenching requirement.

Thickness Tolerances (Hot-Rolled – ASTM A480):

Width Tolerances (Hot-Rolled – ASTM A480):

Flatness Tolerances:

Raw Material Selection: High-quality S32750 super duplex billets from certified premium mills (Outokumpu, Sandvik) with certified chemical composition and ferrite/austenite balance. Raw material is VIM-VAR (Vacuum Induction Melted – Vacuum Arc Remelted) for optimal cleanliness and is NORSOK M-630 qualified and NACE MR0175 compliant.

Reheating: Billets heated to a carefully controlled, narrow temperature range (lower than duplex 2205 to prevent ferrite coarsening and intermetallic formation). Temperature monitoring is continuous.

Hot Rolling: Heated billets passed through roughing and finishing stands to reduce thickness to 3-12mm (hot-rolled coils) with strict temperature control and reduced reduction rates.

Laminar Cooling: Controlled water cooling to prevent intermetallic phase formation.

Coiling: Hot-rolled strip coiled at approximately 600-650°C with controlled tension.

Solution Annealing: Hot-rolled coils undergo solution annealing at 1050–1120°C to restore balanced duplex microstructure and dissolve intermetallic phases.

Water Quenching: Immediate water quenching after annealing (<30 seconds delay). This is the most critical step in super duplex coil manufacturing. Air cooling is unacceptable.

Pickling: Removal of oxide scale using specialized pickling acids optimized for super duplex grades (mixed acid with controlled HNO₃/HF ratio).

Ferrite Content Measurement: Verification of phase balance using magnetic induction or metallographic methods – requirement: 35–65% ferrite (minimum 40% for sour service).

Microstructure Examination: Verification of balanced dual-phase structure, absence of intermetallic phases (sigma, chi, etc.) – per NORSOK M-630.

Cold Rolling (Optional): For thicknesses below 3.0mm, hot-rolled coils further reduced through cold rolling passes.

Cold Rolling Annealing (Optional): Intermediate annealing for cold-rolled coils.

Slitting (Optional): Wide coils cut into narrower strips per customer requirements (20mm to 600mm width).

Inspection & Testing: Dimensional check, PMI, ferrite measurement, mechanical testing, surface inspection, corrosion testing.

Coiling & Packaging: Coiled to specified ID/OD, wrapped with moisture barrier paper, steel strapped.

Chemical Analysis: Positive Material Identification (PMI) 100% verification using handheld XRF spectrometer for Cr (24-26%), Ni (6-8%), Mo (3-5%), N (0.24-0.32%) – high alloy content verification critical.

Ferrite Content Measurement: Magnetic induction (ferritoscope) or metallographic method – requirement: 35–65% ferrite (minimum 40% for sour service), documented on test report.

Microstructure Examination: Verification of balanced dual-phase structure, absence of intermetallic phases (sigma, chi, etc.) – per NORSOK M-630.

Mechanical Testing: Tensile strength (≥800 MPa), yield strength (≥550 MPa), elongation (≥25%), hardness (≤310 HBW / ≤32 HRC) per ASTM A370.

Charpy Impact Testing: Per NORSOK M-630 at -46°C – ≥70J typical for longitudinal, documented.

Dimensional Inspection: Thickness, width, flatness, coil ID/OD using calibrated instruments.

Surface Inspection: Visual check for surface defects, cracks, laps, roll marks, and consistency.

Pitting Corrosion Test: ASTM G48 Method A – 24 hours in 6% FeCl₃ at 40°C (or 50°C for NORSOK) – no pitting allowed. Mandatory for NORSOK compliance.

Critical Pitting Temperature (CPT): ASTM G48 Method C – optional upon request. Typical CPT ≥ 80°C.

Intergranular Corrosion Test (IGC): ASTM A262 Practice E – validates resistance to sensitization.

Sour Service Qualification (upon request): HIC per NACE TM0284, SSC per NACE TM0177 – fulldocumentation available.

NACE MR0175 / ISO 15156 Compliance: Full documentation with hardness verification.

NORSOK M-650 Qualification: Complete documentation package available upon request.

Third-Party Inspection: SGS, BV, DNV, TUV, LR, or ABS on customer request.

Deepwater Subsea Oil & Gas: Subsea manifold shells, pipeline end termination (PLET) components, jumper structures, subsea distribution unit housings, umbilical termination assemblies, subsea control module enclosures (ISO 13628-4 compliant, ABS/BV/DNV certified to 3000m water depth).

HP/HT Sour Gas Facilities: Wellhead platform components, sour gas processing vessels, amine unit tanks, gas dehydration unit shells, produced water treatment vessels, glycol regeneration tanks (NACE MR0175 compliant, highest H₂S limits).

Offshore Platforms (Critical Service): Topside HP/HT module housings, riser support structures, flare tower components, crane pedestal structures, equipment skid frames (NORSOK M-630 certified).

Desalination Plants (High Temperature): High-pressure brine vessels, energy recovery device housings, evaporator shells, multi-stage flash (MSF) evaporator components, zero liquid discharge (ZLD) tanks, brine heater shells.

Flue Gas Desulfurization (FGD): Absorber tower shells, slurry tanks, quench nozzle housings, reheat ductcomponents, scrubber vessels, gypsum tank shells – for high-chloride, low-pH zones.

Chemical Processing (Aggressive Acids): HP/HT heat exchanger shells, reactor vessels, acid storage tanks, high-chloride organic compound process vessels, phosphoric acid evaporator shells, titanium dioxide production vessels.

Hydrometallurgy: Pressure acid leaching (PAL) vessel shells, high-temperature solvent extraction tanks, electrowinning cell housings, nickel/cobalt/copper processing equipment.

Geothermal Energy: High-temperature, high-chlorine, high-H₂S brine pipeline components, steam condensate vessels, reinjection well head structures, geothermal wellhead equipment.

Military/Naval (Critical Systems): Naval vessel structural components (non-magnetic requirement), submarine pressure hull components, degaussing system structures (classification society certified).

LNG Liquefaction Plants (Cold Service): Cold box structural components, low-temperature process vessels, cryogenic piping supports (impact tested at -50°C).

Womic Steel offers precision slitting services for super duplex 2507 coils:

Standard Packaging:

Coils wrapped with moisture-proof paper and VCI (Vapor Corrosion Inhibitor) film

Outer steel strapping (4-8 straps per coil depending on weight)

Wooden pallet or steel skid for coil protection during transport

Plastic edge protectors for slit coils

Clear labeling with grade (S32750/F53), heat number, dimensions, coil weight, ferrite content, NACE compliance, and order number

Womic Steel's Shipping Strengths:

Direct cooperation with global shipowners (Maersk, MSC, COSCO, Hapag-Lloyd) for competitive freight rates

Professional loading and securing teams using non-metallic slings and padded supports prevent coil damage during transit (horizontal or eye-to-sky positioning)

Efficient document preparation (EN 10204 Type 3.1 MTR, EN 10204 Type 3.2 upon request, NORSOK M-630 documentation, NACE compliance certificates, ferrite measurement records, PMI reports, corrosion test reports, Charpy impact test reports, heat treatment charts) minimizes customs delays

Rapid delivery time – standard coils (thickness 3-8mm, width 1500mm) maintained in ready stock

Continuous cargo tracking and after-sales follow-up with destination agent support

1. What is the difference between Super Duplex 2507 and Duplex 2205 coils?
Super Duplex 2507 has higher chromium (24-26% vs 22-23%), higher molybdenum (3-5% vs 3-3.5%), and higher nitrogen (0.24-0.32% vs 0.14-0.20%), giving PRE ≥42 (vs ≥35) and higher strength (YS ≥550 MPa vs ≥450 MPa). For deepwater subsea, HP/HT sour gas, and extreme chloride environments, 2507 is the preferred material.

2. What is the maximum water depth for Super Duplex 2507 coils?
With proper design, Super Duplex 2507 structural components are suitable for water depths up to 3000 meters (10,000 feet) for subsea applications. External pressure collapse rating verified per API 17D.

3. Can Super Duplex 2507 coils be welded?
Yes, but strict procedure required. Use ER2594 filler, low heat input (0.3-1.0 kJ/mm), N₂ shielding gas, interpass temperature <150°C. No post-weld heat treatment required.

4. What is the maximum service temperature for Super Duplex 2507 coils?
250°C (482°F) for chloride service; 300°C (572°F) for non-chloride service. Above 300°C, risk of sigma phase embrittlement increases significantly.

5. Are Super Duplex 2507 coils suitable for sour service (H₂S environments)?
Yes. Super Duplex 2507 is fully NACE MR0175 / ISO 15156 compliant for sour service up to 232°C (450°F) with the highest allowable H₂S partial pressure limits for duplex stainless steels. HIC (NACE TM0284) and SSC (NACE TM0177) test reports available upon request.

6. Do Super Duplex 2507 coils require special surface preparation for painting?
Grit blasting is recommended to create a uniform surface profile for paint adhesion on topside offshore structures. The annealed and pickled finish is suitable for most subsea and immersion applications without painting.

7. What is the minimum design temperature for Super Duplex 2507 coils?
-50°C (-58°F) based on Charpy impact testing at -46°C (-50°F) with ≥70J typical. For lower temperatures, consider austenitic stainless steel grades (304L, 316L, 321, 347) which maintain toughness at cryogenic temperatures.

Highest Strength Available: 2.7-3.2x stronger than 316L – significant weight reduction for offshore structures

Deepwater Subsea Certified: ABS, BV, DNV, LR certified for water depths up to 3000m

NACE MR0175 / ISO 15156 Compliant: Highest H₂S partial pressure tolerance for sour service, with HIC/SSC test reports

NORSOK M-630 Qualified: Complete documentation packages for offshore and subsea projects

Ferrite Controlled: 35-65% ferrite documented on each coil (minimum 40% for sour service)

Charpy Impact Tested: -46°C (-50°F) documented as standard for offshore projects

ASTM G48 Corrosion Tested: Pitting resistance verified; copies of test reports available

Full Traceability: Heat number on each coil – traceable to original mill certificate

Complete Size Range: Thickness from 2.0mm to 12.0mm – standard and custom sizes

Slitting Services: In-house slitting capability for narrow strips (20mm to 600mm)

Flexible Customization: Special widths, surface finishes, and non-standard sizes available

Global Delivery: Exported to major deepwater subsea, HP/HT sour gas, and extreme offshore projects worldwide including Gulf of Mexico, North Sea, Brazil Santos Basin, West Africa, and Southeast Asia

Tel / WhatsApp:

Victor: +86 15575100681

Jack: +86 18390957568

E-mail: info@womicstainless.com

Website: www.womicsteel.com

Contact Womic Steel today for a competitive quote on Super Duplex 2507 stainless steel coils. We offer certified quality, NORSOK M-630 compliance, NACE MR0175 certification, ferrite-controlled material, and reliable global delivery for your deepwater subsea and HP/HT sour gas projects.

Stock Examples (Hot-Rolled Super Duplex 2507 Coils – Annealed & Pickled – Subsea/Offshore Grade):

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