Bar and Rod
Plate and Sheet
Strip
Pipe and Tube
Wire
Welding
Powder Material
Cast Products
Forged Products
Fittings
Fastening
Round Bar:
φ2–500 mm, 1–6 m length
Flat/Square Bar:
4–100 mm thickness/width
Hex Bar:
A/F 3–100 mm
Hollow Bar:
OD 20–300 mm
Sheet:
0.3–6 mm thickness
Medium Plate:
6–25 mm thickness
Heavy Plate:
25–100 mm thickness
Standard Strip:
0.05–3 mm thick,
10–600 mm wide
Precision strip:
0.01–0.5 mm thick,
tight tolerance ±0.005 mm
Foil:
0.005–0.1 mm thick
Seamless Tube:
OD 6–450 mm,
WT 1–50 mm,
1–12 m length
Welded Tube:
OD 10–600 mm,
WT 1–20 mm
Capillary Tube:
OD 1–10 mm,
WT 0.1–2 mm
Wire Form:
Cold Drawn Wire,
Bright Wire,
Spring Wire,
Fine Wire,
Ultra-fine Wire
General Diameter:
φ0.1–10 mm
Coil Weight:
50–500 kg,
customizable tolerance
Solid Wire:
φ0.8–4.0 mm
Flux-cored Wire:
φ1.2–4.0 mm
Welding Rod:
φ2.0–5.0 mm
Powder Form:
AM 3D Printing Powder,
Spherical Powder,
Gas-atomized Powder,
Water-atomized Powder
Particle Size:
10–150 μm
Sphericity:
≥90% for AM grade
Cast Ingot:
φ200–800 mm
Precision Casting:
min wall 0.5 mm
Cast Pipe:
OD 100–600 mm,
WT 10–50 mm
Forged Bar:
Φ35–500 mm
Forged Ring:
OD 200–2000 mm
Forging Weight:
1–5000 kg
Fittings Form:
Elbow, Tee, Reducer, Flange, Cap, Outlet, Lap Joint
Size range:
1/2''–24'' (DN15–DN600)
Wall thickness:
Sch10–Sch160, STD, XS, XXS
Pressure Class:
150–2500 LB
Fastening Form:
Bolt, Nut, Screw, Stud, Washer, Pin, Rivet
Metric: M3–M64
Imperial: #4–2.5''
Length: 6–500 mm
Super Duplex F55 is a tungsten- and copper-bearing super duplex stainless steel, with a microstructure of roughly equal ferrite and austenite. This datasheet presents the material within the American standard system.
With about 25% chromium, 7% nickel, 3.6% molybdenum, plus deliberate tungsten and copper additions and nitrogen, Super Duplex F55 has a pitting-resistance equivalent number (PREN) of at least 40, giving outstanding resistance to chloride pitting, crevice corrosion and stress-corrosion cracking, with a critical pitting temperature above 50 °C. The tungsten and copper additions distinguish it from 2507 and improve resistance in seawater and to non-oxidizing acids such as sulphuric and hydrochloric. It offers roughly double the yield strength of austenitic grades.
Typical applications include oil-and-gas subsea and topside equipment, seawater systems, desalination plant, acid-leach mining, pulp-and-paper and chemical-process equipment, and high-strength corrosion-resistant components.
| Property | Value | Unit |
|---|---|---|
| Density | 7.8 | g/cm³ |
| Melting range | 1350-1400 | °C |
| Young's modulus (20 °C) | 200 | GPa |
| Thermal conductivity (20 °C) | 15 | W/m·K |
| Coefficient of thermal expansion (20-100 °C) | 13 | µm/m·°C |
| Specific heat (20 °C) | 480 | J/kg·K |
| Magnetic response | Ferromagnetic (duplex) | — |
| Element | Symbol | Min % | Max % | Role in Alloy |
|---|---|---|---|---|
| Iron | Fe | Balance | — | Base element |
| Chromium | Cr | 24.0 | 26.0 | Ferrite former; corrosion resistance |
| Nickel | Ni | 6.0 | 8.0 | Austenite former; phase balance |
| Molybdenum | Mo | 3.0 | 4.0 | Pitting + crevice resistance |
| Tungsten | W | 0.50 | 1.00 | Pitting resistance |
| Copper | Cu | 0.50 | 1.00 | Non-oxidizing-acid resistance |
| Nitrogen | N | 0.20 | 0.30 | Austenite former; strength; pitting |
| Manganese | Mn | — | 1.00 | Deoxidiser |
| Silicon | Si | — | 1.00 | Deoxidiser |
| Carbon | C | — | 0.030 | Low (intergranular resistance) |
| Phosphorus | P | — | 0.030 | Residual impurity |
| Sulphur | S | — | 0.010 | Residual impurity |
Solution-annealed condition, per ASTM A240 for UNS S32760.
| Property | Value | Unit |
|---|---|---|
| Tensile strength | >=750 | MPa |
| 0.2% yield strength | >=550 | MPa |
| Elongation at break | >=25 | % |
| Brinell hardness | <=270 | HB |
| Rockwell hardness | <=32 | HRC |
Confirm against the mill test report.
| Environment | Performance | Notes |
|---|---|---|
| Chloride pitting | Outstanding | PREN >=40; CPT > 50 °C |
| Crevice corrosion | Outstanding | Cr + Mo + W + N |
| Chloride SCC | Excellent | Duplex structure |
| Non-oxidizing acids (H₂SO₄, HCl) | Excellent | Copper addition |
| Seawater | Excellent | Warm chlorinated seawater |
| Sulphide / sour | Good | Listed in NACE MR0175 |
The tungsten + copper additions give a balanced PREN-controlled corrosion resistance suitable for the most aggressive chloride and acid service.
Not hardenable by heat treatment; properties are set by solution annealing and phase balance.
Solution Anneal approximately 1100-1140 °C, followed by rapid water quench to retain the balanced ferrite-austenite structure and avoid embrittling intermetallic phases. Rapid cooling is critical owing to the high alloy content. Avoid prolonged exposure in the 300-1000 °C range (sigma-phase / 475 °C embrittlement).
Weldable by common fusion methods; use a matching super-duplex filler (e.g. 25 9 4-type) and controlled heat input to maintain phase balance.
| Process | Applicability | Filler / Consumable |
|---|---|---|
| GTAW / TIG | Good | Matching super-duplex filler |
| GMAW / MIG | Good | Super-duplex filler |
| SMAW / stick | Good | Matching super-duplex electrode |
No preheat; control interpass temperature (typically <=150 °C) and heat input to prevent sigma-phase formation.
Machining Guidelines
| Parameter | Recommendation |
|---|---|
| Machinability | Difficult; high strength + work-hardening; rigid setup, carbide tools, low speeds |
| Work hardening | High rate; positive feeds, avoid dwelling |
| Coolant | Ample flood coolant |
Forming Processes
| Process | Notes |
|---|---|
| Hot forming | ~1200-1000 °C; solution anneal + quench afterward |
| Cold forming | Higher forces than standard duplex (very high strength) |
| Industry | Typical Components | Key Requirements |
|---|---|---|
| Oil & gas | Subsea, topside, downhole equipment | Pitting + sour-service resistance |
| Marine / seawater | Seawater systems, pumps, valves | Warm chloride resistance |
| Mining | Acid-leach equipment | Sulphuric-acid resistance (Cu) |
| Desalination | Heat exchangers, piping | Hot chloride resistance |
| Chemical / pulp & paper | Vessels, piping | Localized-corrosion resistance |
| Product Form | Standard | Notes |
|---|---|---|
| Plate, sheet and strip | ASTM A240 / ASME SA-240 · UNS S32760 | — |
| Forgings / fittings / flanges | ASTM A182 | — |
| Bar and shapes | ASTM A276 / A479 · UNS S32760 | — |
| Seamless / welded tube | ASTM A789 · UNS S32760 | — |
| Seamless / welded pipe | ASTM A790 · UNS S32760 | — |
| Sour service | NACE MR0175 / ISO 15156 | Acid-gas applications |
Tungsten- and copper-bearing 25Cr super duplex stainless steel. UNS S32760.
| UNS | Cr % | Ni % | Mo % | W % | Cu % | Best Used For |
|---|---|---|---|---|---|---|
| Super Duplex F55 | 24-26 | 6.0-8.0 | 3.0-4.0 | 0.5-1.0 | 0.5-1.0 | W+Cu super duplex; seawater + acids |
| S32750 | 24-26 | 6.0-8.0 | 3.0-5.0 | — | — | Super duplex (no W/Cu) |
| S32550 | 24-27 | 4.5-6.5 | 2.9-3.9 | — | 1.5-2.5 | Cu-bearing super duplex |
| S32520 | 24-26 | 5.5-8.0 | 3.0-5.0 | — | 0.5-3.0 | Cu/N super duplex |
| S32205 | 22-23 | 4.5-6.5 | 3.0-3.5 | — | — | Standard duplex |
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