Views: 5 Author: Wang Publish Time: 2024-03-28 Origin: Site
Super Duplex UNS S32760 / F55 / 1.4501 is among the most common super duplex grade in the market. UNS S32760 is duplex stainless steel specially 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.
S32760 super duplex stainless steel is developed to be used in aggressive environments. Properties of S32760 include toughness, high strength, corrosion resistance in a large number of organic and inorganic acids. Finally it features high resistance to strong alkalis and resists corrosion in a number of non-oxidizing acids. While involving extended exposure to temperatures more than 572F use of S32760 is not recommended. The chemical composition of S32750 and S32760 are similar; however, the latter contains slightly more copper and tungsten. The copper content (min. 0.5, max 1.0) permits excellent resistance to corrosion in many non-oxidizing and mineral acids like hydrochloric and sulfuric acid.
Stainless steel grade F55 has excellent corrosion resistance to a wide range of areas, especially resistance to pitting and crevice corrosion in seawater and other chloride-containing environments, with critical pitting temperature that is more than 50°C (122°F). This material is known to also have high strength and an extended lifecycle. It is 10% lighter than grade 316 steel, ideal for sub-zero service, and more cost-effective than nickel alloys. Stainless steel grade F55 can be easily machined and welded.
Super Duplex UNS S32760 is among the most common super duplex grade in the market. UNS S32760 is a duplex 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. Containing 25% chromium, 7% nickel, 3.6% molybdenum as well as copper, tungsten, and nitrogen, UNS S32760 is a highly alloyed super duplex stainless steel with high PREN for use in aggressive environments.
Super duplex S32760 (F55) combines the desirable aspects of both austenitic and ferritic grades and gives significant life cycle cost advantages when used in severe and corrosive conditions. It has exceptional resistance to pitting, crevice corrosion and to stress corrosion cracking and have high strength combined weldability. The higher chromium, molybdenum and nitrogen contents result in a Pitting Resistance Equivalent number (PREN) of >40, providing pitting and crevice corrosion resistance superior to austenitic and duplex stainless steels in almost all corrosive media. It also provides higher strength than both austenitic and 22% Cr duplex stainless steels.
This is a Super Duplex Din 1.4501 grade with a ferritic-austenitic microstructure. The alloy consists of around 40-50% ferrite in the annealed condition. 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, which is the Achilles’ heel of stainless steel.
Well known for its high impact strength, UNS S32760 displays no ductile-brittle transition but only a slight reduction in impact energy as temperature decreases. Even when welded, UNS S32760 displays only slightly lower impact strength. It also has outstanding resistance against sulphide-stress corrosion cracking in sour-gas environments. It was initially developed as a seawater resistant material for pump applications in the North Sea. Following its success, it became the desired material for a wide range of uses including oil and gas applications, seawater, subsea pipework systems, heat exchangers and more.
Super Duplex UNS S32760 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.
Corrosion Resistance
Super duplex UNS S32760 offers high resistance to pitting corrosion, crevice corrosion and stress corrosion cracking. For optimum corrosion resistance a surface finish of pickled or machined is recommended.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.
Welding
Welding procedures are similar to those applied for conventional duplex stainless steel grades. Electric arc welding processes is suitable for UNS S32760 super duplex stainless steel, though oxyacetylene welding is not recommended due to the possibility of carbon pick up in the weld area. We recommend you contact your welding consumables supplier who should provide you full assistance and information of welding UNS S32760 super duplex.
Heat Treatment
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. UNS S2760 1.4501 F55 cannot be hardened by conventional heat treatments, though this is a work hardening steel. Super duplex can be solution annealed at 1110-1140ºC, water quench.
UNS S32760 material for onshore industry and the S32760 Steel Products for offshore industry alike perform well under marine conditions. Both in the sea water and outside sea water, the material shows greater corrosion resistance and stress corrosion cracking resistance. Werkstoff UNS S32760 material for oil and gas industry is typical. The low thermal expansion rates along with corrosion resistance for prolonged periods of time under certain temperatures ranges make it possible. The high tensile strength makes UNS S32760 Zeron 100 pressure vessel material to perform under heavy pressure in vessels and hydraulic systems. It can withstand some of the high wear and tear conditions within high pressure systems in hydraulic applications.
Also due to the lower thermal expansion rates, UNS S32760 F55 casting material is used to retain the precision of the molds even under casting temperatures. S32760 Duplex spring material is used in automobile systems due to the high tensile strength of the material. The high tensile strength also enables Super Duplex UNS S32760 building material to be very efficient where strength is more important. In constructions like bridges, super duplex materials provide the high strength. Super Duplex Grade S32760 angle material makes the angles sit tight and strong. It gives the connecting components a stronghold to be connected on. Super Duplex Stainless Steel S32760 can also be used in place of other super duplex steel materials if the application does not specifically require any particular super duplex steel type.