The Difference between Ferritic Stainless Steel and Austenitic-ferritic Duplex Stainless Steel

In the large family of stainless steel, ferritic stainless steel and austenitic-ferritic duplex stainless steel are both members of stainless steel, but there are obvious differences between them in many aspects. In today’s article, we will introduce the difference between ferritic stainless steel and austenitic-ferritic duplex stainless steel.

The difference between ferritic stainless steel and austenitic-ferritic duplex stainless steel:

The difference in material composition is ferritic stainless steel. This type of steel generally does not contain nickel. In addition to 11% to 30% of chromium, it also contains small amounts of Mo, Ti, Nb and other elements. Austenitic-ferritic duplex stainless steel usually contains 18% to 28% Cr and 3% to 10% Ni. In addition, some steels also contain elements such as Mo, Cu, Si, Nb, Ti, and N.

Differences in crystal structure, ferritic stainless steel is stainless steel with a mainly ferrite structure. Austenitic-ferritic duplex stainless steel is a stainless steel with austenite and ferrite structures accounting for about half each, which also makes this type of steel have the characteristics of both austenitic and ferritic stainless steel.

Differences in corrosion resistance. Although ferritic stainless steel has excellent resistance to stress corrosion, its corrosion resistance range is relatively narrow, such as in humid environments such as the atmosphere and water vapor, and it is susceptible to intergranular corrosion when quenched from above 925°C. Austenitic-ferritic duplex stainless steel, because it has two structures at the same time, combines the advantages of both in terms of corrosion resistance. The resistance to intergranular corrosion and chloride stress corrosion has been significantly improved, and it can adapt to more complex corrosion environments. .

Differences in mechanical properties: Ferritic stainless steel generally has moderate strength, but has certain limitations in toughness and plasticity. Compared with ferrite, austenite-ferrite duplex stainless steel has higher strength, toughness and plasticity, and has excellent fatigue resistance, which makes it more advantageous in situations where it needs to withstand larger external forces and impacts.

Differences in application. Although ferritic stainless steel developed earlier, its industrial application has been greatly restricted. It is mostly used to manufacture parts that are resistant to atmospheric, water vapor, water and oxidizing acid corrosion. Austenitic-ferritic duplex stainless steel, due to its good production process performance, can smoothly produce plates, tubes, bars, forgings and castings of various common specifications using conventional means of producing special steel, and is widely used in Equipment and structures in harsh environments such as chemical industry, petroleum, and ocean.

Due to the difference in cost, the price of ferritic stainless steel is not only relatively low and stable, but also can be replaced by ferritic stainless steel in many application fields where it was originally thought that only austenitic-ferritic duplex stainless steel could be used. In comparison, austenitic-ferritic duplex stainless steel is not only difficult to process, but also more expensive. However, considering the superior comprehensive properties of austenitic-ferritic duplex stainless steel, its cost performance may be higher in some application scenarios with higher performance requirements.

Conclusion

In short, ferritic stainless steel and austenitic-ferritic duplex stainless steel each have their own characteristics. Understanding the differences between the two will help us choose the most suitable stainless steel material in practical applications to ensure that the project or product performance and reliability.

Thank you for reading our article and we hope it can help you to have a better understanding of the difference between ferritic stainless steel and austenitic-ferritic duplex stainless steel. If you are looking for stainless steel suppliers and mabufacturers online now, we would advise you to visit Sino Stainless Steel for more information.

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