This book describes the details of the research and development of nickel-saving high nitrogen austenitic stainless steel and high nitrogen steel (HNS) with excellent corrosion resistance in the sea. This resistance was realized by using nitrogen (N), one of the ubiquitous elements, as an alloying element. By using N it is possible to save nickel (Ni), a national strategic substance in Japan, to be partially reduced or to be totally free. Not only basic information about low nickel HNS but also its promising application to bipolar plates of solid polymer fuel cells are provided. Reduction of Ni ions in the cell environment can be expected to extend the life of the fuel cell. Furthermore, there is discussion of the serendipitous application and impact of nickel-free HNS in the field of biomaterials as an anti-nickel allergy material, leading to its development for coronary stents.
The book includes an explanation of how to develop extremely high corrosion-resistance steel by controlling its level of oxygen. For researchers and engineers involved in the development and evaluation of corrosion-resistant materials in particular, this book is extremely helpful for understanding the details of the development of those materials.

Dr. Yasuyuki KATADA received his PhD from Osaka University in 1980. After working as a research associate at Osaka University during 1979-1981, he moved to NRIM (National Research Institute for Metals) of the Science and Technology Agency. NRIM was reorganized as National Institute for Materials Science (NIMS) in 2001. During his 30-year research life in NIMS, he engaged in nuclear safety research, development of corrosion resistant metallic materials in the Ultra Steel Project and the development of biomaterials. He has reported 67 articles and has published several books including metallic biomaterials so far. He won the Academic Contribution Award "The Mishima Prize" from the Iron and Steel Institute of Japan in 2003, and the New Technology Award from Japan Society of Mechanical Engineers in 2010. He retired from NIMS in 2010. He was appointed as an honorary researcher of NIMS in 2018. 
 Mr. Kazuo HIROSE joined Kobe Steel Ltd. in 1956 and engaged mainlyin material design and manufacturing large-sized components such as precipitation hardening type heat resistant stainless steel and large rotor materials by VOD-ESR. In the meanwhile, as an expert on the design and manufacture of large steel ingots by ESR method, he has reported his research results at several international conferences such as the International Conference on Vacuum Metallurgy (Tokyo, Japan, 1982), International Forging Conference (Sheffield, England, 1985), Forgemaster Meeting (Terni, Italy , 1991). In 1997, he retired from Kobe Steel Ltd. and moved to Kobelco Research Institute Inc., which is a comprehensive testing and research institute under Kobe Steel Ltd.. The Ultra Steel Project started at NIMS in 1997, and in the project a pressurized ESR furnace was planned to be developed for the first time in Japan. Mr. HIROSE played an important role as a cooperative researcher of the project, and he made a great contribution to the establishment of high-nitrogen stainlesssteel manufacturing technology at NIMS. He retired from Kobelco Research Institute Inc. in 2007. 
Dr. Masanobu KUMAGAI received his PhD from Iwate University in 2009. He graduated from Iwate University in 2002 and worked at Taiyo Stainless Spring Co., Ltd in 2002-2014. He was concurrently serving as an external researcher at NIMS from 2009 to 2013. After working at Taiyo Stainless Spring Co., Ltd, he moved to NACHI-FUJIKOSHI Co., Ltd, from 2015 to 2018. After working at Fujikoshi, he moved to JFE Techno-Reserch Co.Ltd in 2018. During 17 years of research and development he is working on the development of stainless steel bipolar plates for polymer electrolyte fuel cells (PEFCs). He has reported 17 articles on the evaluation of corrosion resistance and surface modification of stainless steel under PEFCs environment.