S32760 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, S32760 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 |
|---|---|---|---|---|---|---|
| S32760 | 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 |




