UNS S32760 is the most common super duplex stainless steel grade, UNS S32760 is a duplex stainless steel especially designed for service in aggressive chloride-containing environments and has additions of W and Cu compared to UNS S32750. It has very good resistance to localized corrosion and stress corrosion cracking in combination with high mechanical strength.
UNS S32760 is a super duplex grade with a ferritic-austenitic microstructure. The super duplex microstructure has the high strength of the ferritic grades whilst retaining the corrosion resistance of the austenitic grades. It is not uncommon to see the metal used as a practical solution to chloride-induced stress cracking.
It also has outstanding resistance against sulphide-stress corrosion cracking in sour-gas environments.
UNS S32760 displays high impact strength, even when welded, UNS S32760 displays only slightly lower impact strength.
S32760 Super Duplex Stainless Steel Characteristics
- Guaranteed corrosion performance (PREn ≥ 40)
- Excellent corrosion resistance in mineral acids such as hydrochloric and sulfuric
- High resistance to pitting and crevice corrosion
- Excellent resistance to stress corrosion cracking in both chloride and sour environments
- High resistance to erosion corrosion and corrosion fatigue
- Excellent mechanical properties
- Possibility for weight reduction over austenitic, standard duplex and nickel base alloys
- Good weldability
UNS S32760 Chemical Composition
The chemical composition of S32760 contains 24-26% chromium, 6-8% nickel, and 3-4% molybdenum as well as copper, tungsten, and nitrogen alloy, UNS S32760 is a highly alloyed super duplex stainless steel with high PREN for use in aggressive environments.
| Cr | Ni | Mo | W | Cu | C | Mn | N | Si | P | S | Fe | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Min | 24.00 | 6.00 | 3.00 | 0.50 | 0.50 | 0.20 | ||||||
| Max | 26.00 | 8.00 | 4.00 | 1.00 | 1.00 | 0.03 | 1.00 | 0.30 | 1.00 | 0.030 | 0.010 | Bal |
S32760 Super Duplex Mechanical Properties
| Tensile Strength, Mpa (Ksi), Min | Yield Strength, MPa (Ksi), Min | Elongation, %, Min |
|---|---|---|
| 750 (108) | 550 (80) | 25 |
Physical Properties
| Density (Kg/M3) | 7810 |
| Magnetic Permeability (20°C) | 33 |
| Young’s Modulus (KN/Mm2) | 199 |
| Specific Electrical Resistance, 20°C (ΜΩ.M) | 0.8 |
| Mean Coefficient Of Thermal Expansion, 20-300°C (M/M/OC) | 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/M2) | 98 |
Equivalent Grades
- EN 1.4501
- UNS S32760
- Grade F55
- (Zeron 100)
Corrosion Resistance
Alloy S32760 provides excellent corrosion resistance and strength properties. In comparison with UNS S32205, SUS 329J3L, and SUS 329J4L (NAS 64), it offers superior localized corrosion resistance and thus is suitable for use in chemical plants, seawater desalination plants, and similar severe environments.
Welding
Various welding methods are applicable in the same manner as with the standard austenitic stainless steels, including shielded metal arc welding, TIG welding, and plasma welding. The use of welding electrodes for UNS S32760 is recommended. Preheating and post-heating are not necessary. In welding, the interpass temperature should be no more than 100℃ to prevent the formation of intermetallic compounds.
Heat Treatment
Duplex stainless steel cannot be hardened by heat treatment. They can however be work-hardened.
Solution treatment or annealing can be done by rapid cooling after heating to around 1100°C.
Related References
- ASTM A789, ASME SA789 – Seamless and Welded Ferritic/Austenitic Stainless Steel Tubing for General Service
- ASTM A790, ASME SA790 – General Requirements for alloy and Stainless Steel Pipe
- Related References
- ASTM A240/ASME SB240, Standard Specification for Chromium and Chromium-Nickel Stainless Steel Plate, Sheet, and Strip for Pressure Vessels and for General Applications
- ASTM A480, Standard Specification for General Requirements for Flat-Rolled Stainless and Heat-Resisting Steel Plate, Sheet, and Strip
- EN 10088-2, Stainless steels. Technical delivery conditions for sheet/plate and strip of corrosion-resisting steels for general purposes
- EN 10088-3, Stainless steels. Technical delivery conditions for semi-finished products, bars, rods, wire, sections and bright products of corrosion-resisting steels for general purposes
- EN 10088-4, Stainless steels. Technical delivery conditions for sheet/plate and strip of corrosion-resisting steels for construction purposes
- EN 10088-5, Stainless steels. Technical delivery conditions for bars, rods, wire, sections and bright products of corrosion-resisting steels for construction purposes
- ASTM A249, Standard Specification for Welded Austenitic Steel Boiler, Superheater, Heat-Exchanger, and Condenser Tubes
- ASTM A213, Standard Specification for Seamless Ferritic and Austenitic Alloy-Steel Boiler, Superheater, and Heat-Exchanger Tubes
- ASTM A312, Standard Specification for Seamless, Welded, and Heavily Cold Worked Austenitic Stainless Steel Pipes