Introduction
Stainless steel is widely used in many different industries because of its corrosion resistance, strength, and durability. To suit different engineering applications, stainless steel can be classified into different grades according to its material composition. Two of the most predominant types are the austenitic and ferritic stainless steel. Depending on their composition and mechanical properties, they are more suitable for certain applications than others. This article provides an overview of the differences between austenitic and ferritic stainless steel and explains their various advantages.
Characteristics of Austenitic Stainless Steel
Austenitic stainless steel is an alloy of iron, chromium, and nickel. The chromium content of this type of stainless steel is typically between 16-26%, and its nickel content ranges from 8-20%. As a result of its high chromium content, austenitic stainless steel offers excellent corrosion resistance and excellent strength at elevated temperatures. It also has good workability, formability, and weldability.
Due to its high nitrogen content, austenitic stainless steel is non-magnetic and has good mechanical properties when used at a low temperature. It is resistant to oxidation and scaling, making it a great choice for applications requiring durability and corrosion resistance. Additionally, austenitic stainless steel boasts good resistance to stress corrosion cracking, making it suitable for applications that require aggressive environments.
Characteristics of Ferritic Stainless Steel
Ferritic stainless steel is an alloy of chromium and iron. Its chromium content typically ranges from 10-20%, and its iron content is usually above 65%. As opposed to austenitic stainless steel, ferritic stainless steel does not contain any nickel. This type of stainless steel is non-hardenable and has excellent cold forming and welding characteristics.
Furthermore, ferritic stainless steel offers excellent corrosion resistance in moderately corrosive environments and good heat resistance. It also has excellent ductility and can be formed into complex shapes without significant deformation.
Comparison between Austenitic and Ferritic Stainless Steel
The main difference between these two types of stainless steel is their composition. Austenitic stainless steel contains nickel and chromium and provides excellent corrosion resistance and strength, while ferritic stainless steel contains only chromium and offers good heat resistance and ductility. Additionally, austenitic stainless steel has better machinability and formability but it is less resistant to stress corrosion cracking.
In terms of welding, austenitic stainless steel is more suitable for welding than ferritic stainless steel. The weldability of austenitic stainless steel is excellent, while the weldability of ferritic stainless steel is only satisfactory. Lastly, ferritic stainless steel has a lower cost than austenitic stainless steel because it does not contain any nickel.
Conclusion
Austenitic and ferritic stainless steel are two of the most prevalent grades of stainless steel, each offering unique advantages for different applications. Austenitic stainless steel has excellent strength and corrosion resistance, and is suitable for welding, while ferritic stainless steel offers good heat resistance and ductility. Depending on the application, the choice between these two types of stainless steel will be determined by their properties and composition.
