UNS S32304 (China grade: 00Cr23Ni4N) is a low-alloy duplex stainless steel with excellent corrosion resistance and high mechanical strength. It has a wide range of applications in the chemical and petrochemical industries:
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Chemical Composition
– Basic Composition: UNS S32304 consists of 23% chromium and 4% nickel, without molybdenum.
– Trace Elements: The steel also contains trace amounts of nitrogen, carbon, and other elements, which help to improve its overall performance.
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Physical Properties
– Microstructure: After solution annealing treatment, UNS S32304 exhibits a typical microstructure of 50% ferrite and 50% austenite.
– Mechanical Properties: The yield strength of this material is double that of traditional 304L/316L austenitic stainless steel, allowing for weight reduction in design, especially suitable for applications such as pressure vessels.
3.Corrosion Resistance
– Corrosion Resistance: UNS S32304 has corrosion resistance similar to 316L, particularly excelling in pitting and crevice corrosion.
– Stress Corrosion Resistance: Tested in chloride-containing aqueous solutions, UNS S32304 shows superior stress corrosion resistance compared to 304L and 316L.
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Processing and Welding
– Hot Forming: It is recommended to perform hot forming within the temperature range of 1150/900°C and to conduct a new solution annealing treatment after forming to restore its mechanical and corrosion resistance properties.
– Cold Forming: UNS S32304 can be cold formed, although due to its high strength, a greater force may be required to reach the yield point.
– Welding Performance: This material can be successfully welded using various welding methods, including TIG, MIG, and plasma welding, with attention needed to control proper heat input and interpass temperature during welding.
– Forging: S32304 is sensitive to thermal shock. Therefore, it needs to be slowly heated to 1150°C, forged within the temperature range of 1150°C–900°C, and then cooled rapidly in air.
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Application Areas：
UNS S32304
Chemical Industry
– Equipment Manufacturing: Due to the high strength and excellent corrosion resistance of UNS S32304, it is widely used in the manufacture of chemical reactors, heat exchangers, storage tanks, and other equipment. These devices often come into contact with various corrosive chemicals, requiring materials that can resist the erosion caused by these substances.
– Pipeline Systems: In chemical plants, pipeline systems used for transporting various chemicals often employ UNS S32304 for construction. This material not only withstands high pressures but also prevents corrosion caused by chemicals, ensuring the safe transmission of chemical substances.
Petrochemical Industry
– Refining Equipment: During the oil refining process, many operations involve high temperatures and corrosive environments, such as catalytic cracking units and hydroprocessing units. UNS S32304 is chosen as an ideal material for manufacturing these devices due to its good high-temperature resistance and resistance to chloride ion stress corrosion.
– Offshore Platforms: Offshore oil extraction platforms are exposed to corrosive seawater environments year-round, demanding high corrosion resistance from materials. It is not only resistant to seawater corrosion but can also withstand the effects of high salinity, making it highly suitable for constructing critical structural components on marine platforms.
Special Applications
– High Sulfur Environments: In certain petrochemical processes, such as the processing of sour crude oil, high concentrations of hydrogen sulfide gas are produced, which poses higher demands on the materials of equipment. It can effectively resist stress corrosion cracking caused by hydrogen sulfide, ensuring the safe operation of equipment.
– Extreme Temperature Environments: During the transportation and storage of liquefied natural gas (LNG), materials must be able to withstand extremely low temperatures. UNS S32304 exhibits good low-temperature performance, making it an ideal choice for the manufacture of LNG-related equipment.
In summary, UNS S32304 offers an efficient and economical solution in various industries because of its unique composition and excellent physical properties. Whether in extreme environmental conditions or everyday application needs, UNS S32304 demonstrates its reliability and versatility as a high-performance material.
