Material to UNS S32760 is described as a super duplex stainless steel with a microstructure of 50:50 austenite and ferrite.
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.
The characteristic features of high strength and corrosion resistance exhibited by the dual microstructure (50% Austenite, 50% Ferrite) associated with Duplex Stainless Steels, are enhanced by a further addition of Chromium (to 25%), and also Tungsten and Copper.
The alloy's pitting and Crevice Corrosion resistance is better than Standard F51 duplex, The pitting index (PREN) is increased to 40 min from standard F51 Duplex value of 33 min.
Thin sections (Tubulars) are capable of being cold worked to give yield strength of 105 KSI min.
To optimise mechanical properties, avoid clinking, and to avoid deleterious intermetallics within the microstructure; special high temp forming and heat treatment control practices must be followed during processing.
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.
| Scope | C | Si | Mn | P | S | Cr | Ni | Mo | Cu | N | W | PREN | Fe |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Min | • | • | • | • | • | 24.00 | 6.00 | 3.00 | 0.50 | 0.20 | 0.50 | 40.00 | 0.00 |
| Max | 0.03 | 1.00 | 1.00 | 0.030 | 0.010 | 26.00 | 8.00 | 4.00 | 1.00 | 0.30 | 1.00 | • | 0.00 |
(PREN = % Cr + 3.3% Mo + 16% N)
Condition: Solution Annealed and Water Quenched.
| U.T.S | 109 KSI Min | (750 N/mm2) |
|---|---|---|
| 0.2% Proof Stress | 80 KSI Min | (550 N/mm2) |
| Elongation | 25 % | |
| Red of Area | 45 % | |
| CVN Impacts @ -46°C (-50°F) | 45 Joules | (33 ft-lbf) |
NACE MR0175 limits the supply hardness to 28 HRC max.
Material to UNS S32760 is described as a super duplex stainless steel with a microstructure of 50:50 austenite and ferrite.
The steel combines high mechanical strength (typically up to 600 MPa yield strength) and good ductility with outstanding corrosion resistance to marine environments and a wide, diverse range of oil & gas production environments. The alloy is supplied with a PREN(Pitting Resistance Equivalent) at >= 40.0 which guarantees high resistance to pitting corrosion. In addition, the steel offers high resistance to crevice corrosion and stress corrosion cracking.
Ambient and sub-zero (down to minus 50°C) notch ductility is good. These attributes mean that this super duplex steel can be used successfully as an alternative to 300 series stainless steel (such as type 316), standard 22% Cr duplex steel and precipitation hardening stainless steels. Where appropriate the alloy can be considered in lieu of more costly Grade 5 titanium or nickel based alloys.
Machinability & Welding
The machining and welding of this grade of super duplex stainless steel presents no particular problems. Guidance notes are available upon request.
Technical Assistance
Our knowledgeable staff and resident metallurgists will be pleased to assist you further on any technical topic. Smiths Metal Centres Limited also boasts an in-house UKAS Accredited Testing Laboratory which is unique within the multi-metal and plastic stockholding sector. We believe this underlines our total commitment to quality and our ethos of being the complete service provider.
High impact strength at sub-zero temperatures, UNS S32760 displays excellent corrosion resistance.
UNS S32760 is characterized by:
It is widely used in oil & gas, hydropower, pressure vessels, pulp & paper, structural components and chemical tankers.
We offer UNS S32760 Super Duplex Stainless Steel in bar, forgings, sheet, plate, pipe, tube, closed die forgings, flanges and welding consumables.
Processing
We offer processing services throughout the Smiths Group - with more than 30 band saws and a fully automated magazine feed CNC rod blanking line, we can process your material to your exact requirements.
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.
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.
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.
Firstly, the higher price of UNS S32760 is due to its exceptional properties such as superior corrosion resistance and high strength. This material is typically costly and not suitable for large-scale use in cost-sensitive applications.
Secondly, UNS S32760 contains a variety of alloying elements, such as molybdenum, which may lead to an elemental imbalance if its alloying composition is not reasonably adjusted, thus reducing its corrosion resistance. Therefore, special attention needs to be paid to the balance of alloying elements during use.
Finally, UNS S32760 is susceptible to localized corrosion in chloride-containing environments. Although it performs well in most environments, special care needs to be taken when using it in chloride environments to avoid localized corrosion.
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