The use of general descriptive names, registered names, trademarks, ete. in this publication does not imply, even in the absence of a specific statement, that such names are exempt from the relevant protective laws and regulations and therefore free for general use.Typesetting: Camera-ready eopies from authors Cover-Design: MEDIO, Berlin Printed on acid-free paper SPIN 10730039 6213020 5 4 3 2 1 0 to BELA and ISOLDE PrefaceDuring the second half of this century the nitrogen concentration of steel moved in both directions: down in constructional grades by oxygen blowing to prevent brittle fracture upon age hardening at ambient temperature and up in stainless grades to improve strength, corrosion resistance and austenite stability. The gradual recognition of the beneficial effects of this element on the properties of high alloy steels led to a widespread development of high nitrogen steels (HNS) documented by numerous applications and the proceedings of five HNS conferences at LilIe (France) 1988, Aachen (Germany) 1990, Kiev (Ukraine) 1993, Kyoto (Japan) 1996 and HelsinkilStockholm (FinnlandISweden) 1998. The word "high" in HNS is not clearly defined but accounts e.g. for 0.1 mass% of nitrogen in creep resistant steels, 0.9 mass% in stainless grades or 2 mass% in tool steels. "High" best refers to "intentionally raised" by appropriate alloying or by pressure and powder metallurgy. For convenience steel grades are designated by their approximate content of alloying elements in mass% omitting unintentional minor additons of Si, Mn, C, P, S asf. As an example Cr22Ni5M03NO.2 stands for a stainless duplex grade.The present book starts by comparing the effects of nitrogen and carbon on the atomic structure and interaction within the crystallattice. Next the constitution of HNS is investigated leading to specific microstructural features. Based on this background the mechanisms behind the mechanical, chemical and tribological properties of HNS are derived. This concludes the fundamentals treated in chapters one to three. Chapter four comes down to shop practice of manufacturing HNS which, in respect to e.g. melting, hot working, and welding, may be quite different from respective carbon grades. In chapter five, different HNS for special applications are presented like e.g. hardenable steels for stainless bearings, high strength austenitic steels for non-magnetic retaining rings, superaustenitic stainless sheet for the chemical industry or solution nitrided impellers for pumps. Chapter six is an attempt to summarize key aspects of HNS.The book is meant for material scientist working in the field of high alloy steels and also for engineers engaged in materials technology, material selection and design. The work covers a wide scope from the atomic structure to the application of HNS and was written by a metal physicist and an engineer.

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The use of general descriptive names, registered names, trademarks, service marks, etc. in this publication does not imply, even in the absence of a specific statement, that such names are exempt from the relevant protective laws and regulations and therefore free for general use. While the advice and information in this book are believed to be true and accurate at the date of publication, neither the authors nor the editors nor the publisher can accept any legal responsibility for any errors or omissions that may be made. The publisher makes no warranty, express or implied, with respect to the material contained herein.

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