Analysis of the Advantages and Disadvantages of Duplex Stainless Steel

Duplex stainless steel has superior corrosion resistance compared to austenitic stainless steel. It also has a wider range of practical applications. Moreover, due to the presence of ferrite structure in duplex stainless steel, it possesses the performance characteristics of both ferritic and austenitic stainless steels. 

The specific advantages of duplex stainless steel plates are numerous. Firstly, its yield strength is several times higher than that of ordinary austenitic stainless steel, and it also has sufficient plasticity for forming. The wall thickness of storage tanks or pressure vessels made of duplex stainless steel can be reduced by 30% to 50% compared to those made of austenitic stainless steel, which significantly reduces the cost. 

Secondly, duplex stainless steel has excellent resistance to stress corrosion cracking. Especially in environments with chloride ions, even the duplex stainless steel with the lowest alloy content has stronger resistance to stress corrosion cracking than austenitic stainless steel. Stress corrosion is a major problem that ordinary austenitic stainless steel is difficult to solve. 

Among various materials, the 2205 duplex stainless steel, which is the most commonly used, has better corrosion resistance than the ordinary 316L austenitic stainless steel. Moreover, the super duplex stainless steels all possess extremely high corrosion resistance. In some media, such as acetic acid and formic acid, they can even replace the high-alloy austenitic stainless steel, and some corrosion-resistant alloys are also included. 

In addition, duplex stainless steel also has extremely excellent resistance to local corrosion. Compared with austenitic stainless steel with similar alloy content, due to its high strength and good corrosion resistance, the wear resistance, corrosion fatigue resistance and other properties of duplex stainless steel are all superior to those of austenitic stainless steel. 

The linear expansion coefficient of duplex stainless steel is lower than that of austenitic stainless steel and is similar to that of carbon steel. It is more suitable for connection with carbon steel and has significant engineering significance, such as in the production of composite plates or linings. 

Regardless of whether it is under dynamic load or static load, the energy absorption capacity of duplex stainless steel is stronger than that of austenitic stainless steel. This gives duplex stainless steel a significant advantage when it comes to handling sudden incidents such as impacts and explosions for structural components. Its practical application value is also higher. 

However, duplex stainless steel also has some weaknesses. For instance, its widespread usage and versatility do not compare to those of austenitic stainless steel. If used for a long time, the application temperature of duplex stainless steel must be controlled below 250℃. 

Secondly, the plasticity of duplex stainless steel is lower than that of austenitic stainless steel. Its cold and hot processing techniques and forming performance are inferior to those of austenitic stainless steel. 

Furthermore, duplex stainless steel also has a temperature-sensitive brittle zone. Therefore, it is essential to strictly control the processing techniques for heat treatment and welding to prevent the emergence of harmful phases, which could otherwise damage the performance of the duplex stainless steel.