Ferritic stainless steel
Ferritic stainless steel contains less carbon and its microstructure is similar to that of carbon steel and low alloy steel. Compared with other types of stainless steel, due to the lack of toughness of the weld, usually only thin profiles can be used. Nevertheless, ferritic stainless steel is often used by contractors in areas where welding is not required. In addition, ferritic steel can not be hardened by heat treatment. But when molybdenum is added, you can also use it in seawater or other corrosive conditions. Ferritic stainless steel is also magnetic, but not as formable as austenitic stainless steel. On the other hand, iron and steel workers often choose ferritic stainless steel, because its corrosion resistance is not easy to crack.
austenitic stainless steel
Austenitic stainless steel is one of the common types of stainless steel on this single sheet. Its microstructures include nitrogen, nickel and manganese. The structure of austenitic stainless steel is the same as that of common steel. But formability and solderability can only be achieved at higher temperatures. In addition, the corrosion resistance of austenitic stainless steel can be improved by adding nitrogen, chromium and molybdenum. Although it cannot be hardened by heating, once it hardens to a certain strength, austenitic stainless steel will have such a useful performance that it can maintain a certain degree of toughness and ductility. Typical stainless steels are prone to stress corrosion cracking, while austenitic stainless steels with high nickel content will increase their resistance to stress corrosion cracking. The surface of austenitic stainless steel is nonmagnetic, but it shows certain magnetic reaction according to its components.
Martensitic stainless steel
Similar to ferritic stainless steel, martensitic stainless steel has higher chromium and carbon content. Like carbon steel and low alloy steel, martensitic stainless steel can be tempered and hardened. The martensitic stainless steel has moderate corrosion resistance and high strength. As it is one of the types of magnetic stainless steel, its formability and weldability are low. In most cases, some companies will use martensitic stainless steel if they need to use plate products for a long time.
Duplex stainless steel
Duplex stainless steels with Semi-austenitic and semi-ferrite microstructures have higher strength than these types of stainless steels. It also has the characteristics of stress resistance, corrosion resistance and non-cracking. Rare duplex stainless steel with corrosion resistance similar to ordinary Austin stainless steel. But its stress resistance and anti-corrosion cracking performance have been improved. Compared with common austenitic stainless steel, "superduplex" stainless steel also has better corrosion resistance and strength. In addition, they are weldable as long as attention is paid to the use of welding materials at appropriate temperatures. Duplex stainless steel is also magnetic stainless steel with moderate formability.
Precipitation hardening can increase the strength of different types of stainless steel
When Nb, Cu and Al are added, precipitation hardening of stainless steel can produce very high strength. On the other hand, it produces strength by forming very fine particles in the steel matrix during proper "aging" heat treatment. When you work with this type of steel, you can create some complex shapes. However, a good tolerance level is required before the end aging treatment. The corrosion resistance of precipitated hardened steel is comparable to that of ordinary austenitic steel.