Duplex Stainless Steel (DSS) refers to the stainless steel that contains 50% of ferrite and austenite approximately, or at least 30% of duplex generally. In the case of low carbon content, the Cr content is 18% to 28%, and the Ni content is 3% to 10%. Some steels also contain alloying elements such as Mo, Cu, Nb, Ti, and N.
Duplex stainless steel is also a type of steel that embodies excellent corrosion resistance, high strength, and ease of manufacturing. Its physical properties are between austenitic stainless steel and ferritic stainless steel, but are closer to ferritic stainless steel and carbon steel.
Duplex stainless steel has a history of nearly 80 years. In its microstructure, the ferrite phase and the austenite phase each account for about half. The early grades were alloys of chromium, nickel and molybdenum. The first forged duplex stainless steel was produced in Sweden in 1930 and used in the paper industry. These steels are high-carbon duplex stainless steels that were originally developed to reduce intergranular corrosion problems. In 1930 Finland produced duplex stainless steel castings. In 1936, France acquired a patented steel grade, which was later known as Uranus50. After World War II, AISI 329 stainless steel became a mature grade and was widely used in heat exchanger pipes. 3RE60 is one of the first duplex stainless steel grades developed particularly to improve chloride stress corrosion cracking (SCC) resistance. Later, both forged and casted duplex stainless steel grades were used in a variety of processing industries, including vessels, heat exchange and pumps.
The first-generation duplex stainless steel has good properties but has limitations in the welding status. The heat-affected zone (HAZ) of the weld has low toughness due to excessive ferrite, and its corrosion resistance is significantly lower than that of the base metal. These limitations limit the use of first-generation duplex stainless steels and are generally limited to non-welded applications.
The second-generation duplex stainless steel features nitrogen alloying. This new commercialization process began in the late 1970s and coincided with the development of offshore oil and gas fields in the North Sea and meets the demand for stainless steels with excellent chloride ion corrosion resistance, good processability, and high strength.
Duplex stainless steels are constantly evolving. Duplex stainless steels contain a range of grades with different corrosion characteristics. Their corrosion properties depend on their alloy composition.
Duplex stainless steel is also widely used
Petroleum and natural gas
In the petroleum and natural gas industry, duplex stainless steels play a crucial role in assisting to withstand harsh conditions. Duplex stainless steel is mainly used in fluid pipes, process piping systems and equipment such as separation devices, washing devices and pumps. Under the sea, these materials are used in underground piping products, fittings and manifolds, fluid pipes, and pipelines that transport corrosive oil and gas.
Biofuels
The biofuel industry (especially ethanol) is a growing arena of duplex stainless steel applications. 2205 stainless steel has been used in Singapore NExBTL process equipment for biomass oil production. In a large biofuel project in the port of Amsterdam, Dutch tank manufacturer Oostwouder Tank-&Silobouw BV chose S32101 for the oil depot made by Noba Vetveredeling BV.
Construction industry
Duplex steels continue to play an important role in the construction of bridges. Bridges are used in corrosive and salty environments and require high bearing strength. Two recent examples are Hong Kong's Stonecutters Bridge and Singapore's twin-helix pedestrian bridge in Asia. They all use 2205 duplex stainless steel materials.
In addition, duplex stainless steel is also used in many other fields and has significant implications for industrial construction.
Contact
CIVMATS Co., Ltd. excels in producing quality duplex stainless steel materials that can meet your divergent project requirements. Please contact us for more details.
- Company: CIVMATS CO., LIMITED
- Phone: 86-519-81809659
- Fax: 86-519-81809959
- Email: sales@civmats.com
- Address: 10th Floor, Xin Cheng Nan Du, Wujin District, Jiangsu, China
- Website: www.civmats.com
