Due to its unique structural characteristics, duplex stainless steel combines the excellent toughness of austenitic stainless steel with the higher strength and chloride stress corrosion resistance of ferritic stainless steel, making duplex stainless steel both two-phase Advantages, it has been widely used in the petrochemical industry. With the development of the petrochemical industry and the continuous progress of dual-phase steel R&D and manufacturing technology, the application of dual-phase steel in the petrochemical industry will become more and more extensive.
The development and application of duplex stainless steel began in the 1930s. Its development has gone through three stages. The first generation of duplex stainless steel contains high chromium and molybdenum, and has good local corrosion resistance, but its carbon content is high, so it is lost during welding. Phase balance, the precipitation of carbides along the grain boundary leads to a decrease in corrosion resistance and toughness. After welding, it must be heat treated. It is generally used for castings. It is limited in application and development. At this stage, dual-phase steel has not been used in the petrochemical industry. . Since the 1970s, with the emergence and popularization of secondary refining technologies such as AOD and VOD, and the development of continuous casting technology, it is easy to smelt ultra-low carbon steel, improve the shortcomings of the first generation of duplex stainless steel, and develop new In the field of application, my country began to adopt imported dual-phase steel equipment in key parts such as atmospheric and vacuum and catalytic cracking of oil refining units. Since then, dual-phase steel has gradually been promoted and used in my country's petrochemical industry.
The super duplex stainless steel developed in the middle and late 1980s belongs to the third generation of duplex stainless steel. This type of steel is characterized by low carbon content, high molybdenum and high nitrogen, and the ferrite content in the steel is 40%-50%. Steel has excellent pitting corrosion resistance, high mechanical strength, and is widely used in the petrochemical industry.
Since entering the 21st century, the development of duplex stainless steel has shown two development trends. On the one hand, by further increasing the content of alloying elements in the steel to obtain higher strength and better corrosion resistance; on the other hand, turning to the development of economic duplex stainless steel with low nickel content and no molybdenum or only a small amount of molybdenum, in order to reduce the double The cost of phase stainless steel, and significantly improve the hot workability and weldability of duplex stainless steel, thereby increasing the competitive advantage of duplex stainless steel with other types of stainless steel.
With the continuous development of duplex stainless steel in the international arena, as well as the continuous progress of domestic related technologies and the continuous improvement of production equipment, the application of duplex stainless steel in the petrochemical industry has developed rapidly, which has promoted the varieties, specifications, and specifications of duplex stainless steel in my country.The rapid development of quantity and technological progress.