This book provides an exhaustive overview of a class of materials with distinct mechanical and corrosion resistance properties: superaustenitic stainless steels. It strives to fill the gap in the literature on these materials by offering a comprehensive overview based on the author's experience in the metallurgical industry and by organizing information from the available literature. Topics are presented in a structured and detailed manner, accompanied by images and graphs created specifically for this book, including original material like optical micrographs Special attention is also given to cultural-historical aspects that are often overlooked but are critical for understanding the characteristics of the material. Superaustenitic stainless steels (SASSs) take the characteristics of austenitics to the extreme for maximum performance and feature a complex chemical composition of high Cr, Ni, Mo, and N content. The book is divided into four parts: an introduction to stainless steels, a chapter on the specific metallurgy of SASSs, a section on mechanical, physical, and corrosion resistance properties, and a chapter on production technologies, processing, and uses. It also includes extended appendices on the effects of alloying elements in steels and on the characteristics of the phases found in stainless steels. The book is addressed to a wide audience, from university students to professionals and consultants in the field who need literature support to innovate on materials and production processes.