Metallurgy, Properties and Applications of Superaustenitic Stainless Steels—SASSs

Abstract

Superaustenitic stainless steels (SASSs) are one of the families of high-performance stainless steels, the so-called “super” grades. While sharing the face-centered cubic lattice structure typical of standard austenitic stainless steels, their chemical composition is significantly more complex. This enables them to offer an exceptional balance of superior corrosion resistance and high mechanical strength. However, the intricate chemical makeup of SASSs brings challenges, such as the phenomenon of segregation and precipitation of deleterious intermetallics. Consequently, this leads to several challenges in their processing and use. This work aims to present SASSs in detail, starting from their chemistry and metallurgy and ending with processing and applications. Hence, the first part will be dedicated to the analysis of chemistry, resulting grades, microstructure and secondary phases along with the conditions determining their formation. Afterwards, physical, mechanical and corrosion resistance characteristics will be set forth in such a way as to understand their origin and implications for processing and possible uses, with a focus on processability limitations. In fact, manufacturing and processing options significantly affect the types of products that can be developed, and, when considered alongside material attributes and costs, they help define the target markets for these alloys.