Alloy 32760
Also known as Zeron 100®, UNS S32760, EN 1.4501
Alloy 32760 is a super duplex stainless steel with PREN over 40 and outstanding pitting, crevice and stress-corrosion resistance.
Langley Alloys stocks Alloy 32760 as bar and plate, with tube and pipe available on enquiry, cut to size from our UK and USA sites.
Alloy 32760 (UNS S32760) is a super duplex stainless steel developed for the most demanding corrosive environments. With 25% chromium and additions of molybdenum, nitrogen, tungsten and copper, it achieves a Pitting Resistance Equivalent Number (PREN) exceeding 40 and a Critical Pitting Temperature above 50°C.
Its combination of high strength - at least 550 N/mm² proof stress - with outstanding resistance to pitting, crevice corrosion and stress corrosion cracking in chloride environments makes it a preferred choice for subsea, process and marine applications where standard duplex and austenitic grades are insufficient. Listed in NACE MR0175 / ISO 15156 for sour service; ASME Pressure Vessel approval.
We stock bar in the UK and USA, and plate in the USA. Tube and fittings are available on enquiry; forgings and castings to order.
- PREN exceeding 40 - outstanding resistance to pitting and crevice corrosion in seawater and chloride environments
- Critical Pitting Temperature exceeding 50°C
- Higher strength than austenitic and 22%Cr duplex stainless steels
- Excellent ductility and impact strength at both ambient and sub-zero temperatures
- High resistance to abrasion, erosion and cavitation erosion
- Excellent resistance to stress corrosion cracking in chloride environments
- Listed in NACE MR0175 / ISO 15156 for sour service
- ASME Approval for Pressure Vessel application
| Element | Min | Max |
|---|---|---|
| Chromium (Cr) | 24.00 | 26.00 |
| Nickel (Ni) | 6.00 | 8.00 |
| Molybdenum (Mo) | 3.00 | 4.00 |
| Tungsten (W) | 0.50 | 1.00 |
| Copper (Cu) | 0.50 | 1.00 |
| Iron (Fe) | Bal | |
| Manganese (Mn) | - | 1.00 |
| Nitrogen (N) | 0.20 | 0.30 |
| Silicon (Si) | 0.10 | 0.80 |
| Carbon (C) | - | 0.025 |
| Phosphorus (P) | - | 0.025 |
| Sulphur (S) | - | 0.005 |
Work out the PREN for this composition with our PREN calculator.
| Property | Imperial | Metric |
|---|---|---|
| 0.2% Proof stress (min) | 79.8 ksi | 550 N/mm² |
| Tensile strength (min) | 108.8 ksi | 750 N/mm² |
| Elongation (5.65√S0) | 25% | 25% |
| Reduction of area | 45% | 45% |
| Hardness (Brinell) | ≤ 270 HB | ≤ 270 HB |
| Impact strength (Room Temp) | 59 ft.lb | 80 J |
| Impact strength (-46°C) | 44 ft.lb av (33 ft.lb min) | 60 J av (45 J min) |
| Property | Value |
|---|---|
| Density (kg/m³) | 7810 |
| Magnetic permeability (20°C) | 33 |
| Young's modulus (kN/mm²) | 199 |
| Specific electrical resistance, 20°C (µΩ.m) | 0.80 |
| Mean coefficient of thermal expansion, 20-300°C (m/m/°C) | 11.1 x 10⁻⁶ |
| Specific heat, 20°C (J/kg.K) | 475 |
| Thermal conductivity, 20°C (W/m.K) | 14.2 |
| Fracture toughness, kQ (MPa/m½) | 98 |
Equivalents & cross-references
Standard designations
- UNS
- S32760Unified Numbering System
- EN
- 1.4501European harmonised standard
- ASTM
- A182 F55Forgings and fittings A479Bar and shapes A276Bar and shapes
- NORSOK
- MDS D57Material data sheet
- NACE
- MR0175 / ISO 15156Sour service
- API
- 6AWellhead and tree equipment
Alloy 32760 is also designated UNS S32760, EN 1.4501, ASTM A182 F55, ASTM A479, ASTM A276, NORSOK MDS D57, NACE MR0175 / ISO 15156 and API 6A.
Trade name equivalents
-
Zeron 100
Zeron 100 is an alternate designation for Alloy 32760.
Common questions
What is the UNS number for Alloy 32760?
Alloy 32760 is a super duplex stainless steel covered by UNS S32760, with equivalents ASTM A479, ASTM A276, ASTM A182 F55 and EN 10088-3 1.4501. It is supplied in the hot worked and solution annealed condition and is listed in NACE MR0175/ISO 15156, NORSOK MDS D57 and API 6A. Its higher chromium, molybdenum and nitrogen give a Pitting Resistance Equivalent Number (PREN) above 40. Langley Alloys stocks it as bar; tube and fittings are available on enquiry, and forgings and castings are to order.
What is Alloy 32760 used for?
Alloy 32760 is used for oil and gas pumps, valves, pipe, vessels, wellhead and subsea equipment; marine propellers, shafts, rudders, shaft seals, pumps, fasteners and valves; and oil and chemical tankers. Further applications include process components for nitric acid, polypropylene and PVC production, pollution control and flue gas desulphurisation systems, pulp and paper equipment, and desalination and seawater cooling plant.
Is Alloy 32760 suitable for sour service and seawater?
Yes. Alloy 32760 is listed in NACE MR0175 for sour service, with hardness controlled to a maximum of 28 HRC, and holds ASME approval for pressure vessel applications. It offers outstanding resistance to pitting and crevice corrosion in seawater and other chloride environments, with a Critical Pitting Temperature exceeding 50°C and a seawater corrosion rate below 0.01 mm/year. It also has excellent resistance to chloride stress corrosion cracking.
What is EN 1.4501 stainless steel?
EN 1.4501 is the European designation for UNS S32760, a super duplex stainless steel stocked by Langley Alloys as Alloy 32760. It is supplied to ASTM A479, ASTM A276, ASTM A182 F55, NACE MR0175/ISO 15156, NORSOK MDS D57, and API 6A.
What is ASTM A182 F55?
ASTM A182 F55 is the forged fitting designation for UNS S32760, a super duplex stainless steel. Langley Alloys stocks this grade as Alloy 32760 in bar form to ASTM A479 and A276.
What is the density of Alloy 32760?
Alloy 32760 has a density of approximately 7.81 g/cm³ (7810 kg/m³).
Is Alloy 32760 magnetic?
Yes. Alloy 32760 is a super duplex stainless steel with a part-ferritic structure, so it is ferromagnetic (magnetic).
Super duplex, strengthened with tungsten
In this Technical Corner, Rodney covers 32760, the second super duplex grade ever developed and, like Ferralium, born in the UK.
Built on 25% chromium, it uses tungsten where Ferralium leans on copper. Its blend of strength, corrosion resistance and cost has made it a default for fasteners. Langley stocks it half-inch to 16-inch in the UK and US.
Visit our YouTube channelSolution annealed and water quenched as standard.
Processing capability
Cutting
Automated band sawing to 650mm section. CNC sawing at all sites.
Cutting servicesFirst-stage processing
Water jet cutting, turning, boring and grinding undertaken in-house.
Processing servicesInspection & testing
Each bar ultrasonically tested and visually inspected. ASTM G48A pitting corrosion test and ferrite content certification available.
Inspection & testing
Tools for this grade
Pitting & crevice resistance
Pitting & Crevice Resistance
Rank alloys by PREN and get an indicative pitting temperature for a chloride service. Pick a grade and a service temperature to see whether it has margin against pitting, or compare the range in the table below. A first-pass screen for chloride and seawater service.
| Grade | UNS | PREN | Indicative CPT | Relative pitting resistance |
|---|
Indicative screen, not a certified result. PREN ranks pitting resistance; the pitting temperature here is estimated from PREN (CPT ≈ 2.5 × PREN - 50), consistent with Langley's "PREN >40, CPT exceeding 50°C" for super duplex. Real critical pitting/crevice temperature depends on test method, product form, surface finish and service chemistry. Crevice corrosion starts well below the pitting temperature - allow a margin at gaskets, deposits and flange faces. Use certified data for design.
Sour-service screen (NACE MR0175)
Sour-Service Screen
Work out whether a service is sour from the H2S partial pressure, and see each alloy's NACE MR0175 / ISO 15156 status and hardness limit. A first-pass screen for oil & gas material selection - the full environmental envelope for a grade is set in ISO 15156-3 Annex A.
Candidate grade
| Grade | Family | NACE status | Hardness limit |
|---|
First-pass screen only. This shows whether the service is sour (from H2S partial pressure) and each material group's NACE MR0175 hardness limit and general suitability. It does not reproduce the full environmental windows (maximum H2S partial pressure, temperature, chloride, in-situ pH per grade) - those are in ISO 15156-3 Annex A and must be checked there for the specific grade, product form and condition. Qualification also depends on heat treatment, cold work and welding.
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