Nickel-saving Type High Nitrogen Austenitic Stainless Steel 443156926X, 9784431569268

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NIMS Monographs

Yasuyuki Katada Kazuo Hirose Masanobu Kumagai

Nickel-saving Type High Nitrogen Austenitic Stainless Steel

NIMS Monographs Series Editor Naoki OHASHI, National Institute for Materials Science, Tsukuba, Ibaraki, Japan Editorial Board Mikiko TANIFUJI, National Institute for Materials Science, Tsukuba, Japan Takahito OHMURA, National Institute for Materials Science, Tsukuba, Ibaraki, Japan Yoshitaka TATEYAMA, National Institute for Materials Science, Tsukuba, Ibaraki, Japan Takashi TANIGUCHI, National Institute for Materials Science, Tsukuba, Ibaraki, Japan Kazuya TERABE, National Institute for Materials Science, Tsukuba, Ibaraki, Japan Masanobu NAITO, National Institute for Materials Science, Tsukuba, Ibaraki, Japan Nobutaka HANAGATA, National Institute for Materials Science, Tsukuba, Ibaraki, Japan Kenjiro MIYANO, National Institute for Materials Science, Tsukuba, Ibaraki, Japan

NIMS publishes specialized books in English covering from principle, theory and all recent application examples as NIMS Monographs series. NIMS places a unity of one study theme as a specialized book which was specialized in each particular field, and we try for publishing them as a series with the characteristic (production, application) of NIMS. Authors of the series are limited to NIMS researchers. Our world is made up of various “substances” and in these “materials” the basis of our everyday lives can be found. Materials fall into two major categories such as organic/polymeric materials and inorganic materials, the latter in turn being divided into metals and ceramics. From the Stone Ages - by way of the Industrial Revolution - up to today, the advance in materials has contributed to the development of humankind and now it is being focused upon as offering a solution for global problems. NIMS specializes in carrying out research concerning these materials. NIMS: http://www.nims.go.jp/ eng/index.html

Yasuyuki Katada · Kazuo Hirose · Masanobu Kumagai

Nickel-saving Type High Nitrogen Austenitic Stainless Steel

Yasuyuki Katada Emeritus Researcher National Institute for Materials Science Tsukuba, Ibaraki, Japan

Kazuo Hirose Kobe Steel (Japan) Takasago, Japan

Masanobu Kumagai JFE Techno-Research Corporation Kawasaki, Japan

ISSN 2197-8891 ISSN 2197-9502 (electronic) NIMS Monographs ISBN 978-4-431-56926-8 ISBN 978-4-431-56927-5 (eBook) https://doi.org/10.1007/978-4-431-56927-5 © National Institute for Materials Science, Japan 2022 This work is subject to copyright. All rights are reserved by the National Institute for Materials Science, Japan (NIMS), whether the whole or part of the material is concerned, specifically the rights of translation, reprinting, reuse of illustrations, recitation, broadcasting, reproduction on microfilms, or in any other physical way, and transmission or information storage and retrieval, electronic adaptation, computer software, or by similar or dissimilar methodology now known or hereafter developed. Exempted from this legal reservation are brief excerpts in connection with reviews or scholarly analysis or material supplied specifically for the purpose of being entered and executed on a computer system, for exclusive use by the purchaser of the work. Duplication of this publication or parts thereof is permitted only under the provisions of applicable copyright laws and applicable treaties, and permission for use must always be obtained from NIMS. Violations are liable to prosecution under the respective copyright laws and treaties. 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. NIMS and the publisher make no warranty, express or implied, with respect to the material contained herein. This Springer imprint is published by the registered company Springer Japan KK, part of Springer Nature. The registered company address is: Shiroyama Trust Tower, 4-3-1 Toranomon, Minato-ku, Tokyo 1056005, Japan

Preface

It is well known that nitrogen is not only extremely effective in improving the strength and corrosion resistance of steel materials but is also effective as a substitute element for Ni in austenitic stainless steel. However, there are many issues to be clarified, such as nitrogen alloying technology and elucidation of the mechanism of improving various characteristics by alloying nitrogen. Research on high-nitrogen steel in Japan became particularly active after the International Conference on High-Nitrogen Steel (HNS 1985) held in Kyoto. Highnitrogen steel research by a pressurized electroslag remelting (P-ESR) method started in NIMS in 1997 as one of the Ultra Steel Projects. The aim of the project was to develop a super-stainless-steel-grade seawater-resistant resource-saving-type highnitrogen stainless steel. To realize the project, a pressurized electroslag remelting (PESR) system was developed in NIMS for the first time in Japan. Using this equipment, a seawater-resistant high-nitrogen steel with titanium-grade corrosion resistance was successfully developed. Although excellent reviews on HNS have been reported by Rashev (1995) and Berns (2015), the aim of this book is mainly to describe how to manufacture the Nisaving-type HNS on the basis of concrete process flows used by young researchers and students interested in material research and development. Two application studies related to the Ni-saving HNS were conducted; one was on a bipolar plate for a polymer electrolyte fuel cell (PEFC) and the other was on a coronary stent for an anti-Ni-allergy biomedical material using Ni-free HNS. This book also includes the bipolar plate research, while the research on the coronary stent using Ni-free HNS was already reported in 2015. The cross-national HNS research in Japan was conducted by bringing together more than 30 companies, research institutes, and academics to the “Study Group on the Effectiveness of Nitrogen on Various Properties of Steel” (The Iron and Steel

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Preface

Institute of Japan, Chair: Y. Katada (NIMS), 2015). This book cited some valuable achievements from the final report of the study group. Yasuyuki Katada Emeritus Researcher National Institute for Materials Science Tsukuba, Ibaraki, Japan Kazuo Hirose Ex-Engineer Kobe Steel (Japan) Takasago, Japan Masanobu Kumagai Deputy Manager JFE Techno-Research Corporation Kawasaki, Japan

Contents

1 Resource-Saving-Type High-Nitrogen Austenitic Stainless Steel . . . . . . References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

1 3

2 Production of High Nitrogen Steel (HNS) . . . . . . . . . . . . . . . . . . . . . . . . . . 2.1 Metallurgy of HNS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.2 Solid-Phase Nitrogen Absorption Method . . . . . . . . . . . . . . . . . . . . . . . 2.2.1 Outline of Solid-Phase Nitrogen Absorption Method . . . . . . . 2.2.2 Past Research on Solid-Phase Nitrogen Absorption Method . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.2.3 Nitrogen Absorption to Solid Phase and Its Thermodynamics/Kinetics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.2.4 Manufacturing Technology of Nickel-Free Stainless Steel by Solid-Phase Nitrogen Absorption Method . . . . . . . . . 2.3 Research on Producing High-Nitrogen Steel by Mechanical Alloying . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.4 Research on Producing High-Nitrogen Austenitic Steel by MIM . . . 2.5 Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

5 5 7 7

3 Production of High Nitrogen Steel by Pressurized ESR Method . . . . . . 3.1 Development of Pressurized ESR Furnace . . . . . . . . . . . . . . . . . . . . . . . 3.2 Nitrogen Addition Test in the P-ESR Operation . . . . . . . . . . . . . . . . . . 3.2.1 Addition Method of the Nitrogen Source of FCrN . . . . . . . . . 3.2.2 Mixture of Alloying Element Concentrations in the Metal Pool . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.2.3 Method for Creating Primary Electrode for Nitrogen-Added P-ESR Test . . . . . . . . . . . . . . . . . . . . . . . . . 3.2.4 Physical Properties of ESR Slag . . . . . . . . . . . . . . . . . . . . . . . . . 3.3 Results of Nitrogen Addition P-ESR Test . . . . . . . . . . . . . . . . . . . . . . . 3.4 Manufacturing Method of Ni-Free HNS . . . . . . . . . . . . . . . . . . . . . . . . 3.4.1 Manufacturing of Nitrogen Source of FCrN for Ni-Less HNS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

9 9 10 11 12 13 14 17 17 18 20 22 23 24 24 28 28 vii

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3.4.2 Manufacturing of Ni-Free Fe–Cr Alloy . . . . . . . . . . . . . . . . . . . 3.4.3 Production of Primary Electrode Using Pressurized Induction Furnace (PIF) and Melting of Ni-Free HNS by P-ESR Method . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.4.4 Nitrogen In-Take of P-ESR Ingot . . . . . . . . . . . . . . . . . . . . . . . . 3.4.5 Oxygen Content of P-ESR Ingot . . . . . . . . . . . . . . . . . . . . . . . . 3.4.6 Results of Inclusions Investigation . . . . . . . . . . . . . . . . . . . . . . . 3.4.7 Summary of Nitrogen Source Addition P-ESR Test . . . . . . . . 3.5 Deoxidation Technology for Purification of P-ESR Ingot . . . . . . . . . . 3.5.1 Al Deoxidation of P-ESR Operation . . . . . . . . . . . . . . . . . . . . . 3.5.2 Ca Deoxidation of P-ESR Operation . . . . . . . . . . . . . . . . . . . . . 3.5.3 Dephosphorization and Desulfurization by Metallic Ca–100% CaF2 Slag . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.5.4 Nitrogen in the Slag . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.5.5 Summary of the Impurity Reduction Technology of P-ESR Ingot . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

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4 Mechanical Properties of High Nitrogen Steel . . . . . . . . . . . . . . . . . . . . . . 4.1 Material Strength . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.1.1 HNS Manufactured by MIM Method . . . . . . . . . . . . . . . . . . . . 4.1.2 HNS Manufactured by P-ESR Method . . . . . . . . . . . . . . . . . . . 4.2 Ductile–Brittle Transition Temperature (DBTT) Behavior . . . . . . . . . 4.2.1 HNS Manufactured by MIM Method . . . . . . . . . . . . . . . . . . . . 4.2.2 HNS Manufactured by P-ESR Method . . . . . . . . . . . . . . . . . . . 4.2.3 Low-Temperature Embrittlement and Failure Mechanism . . . 4.3 Formability of HNS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.3.1 Cold Rolling and Drawing of HNS . . . . . . . . . . . . . . . . . . . . . . 4.3.2 Problems to Be Solved to Improve Formability of HNS . . . . . References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

39 39 39 41 42 42 43 44 45 45 47 48

5 Corrosion Properties of HNS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5.1 Pitting Corrosion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5.2 Crevice Corrosion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5.3 Pitting Resistance Equivalent . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5.4 Field Tests of HNS in the Sea . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5.5 Mechanism of Improved Corrosion Properties by Addition of Nitrogen . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

49 49 50 52 54

6 Weldability of HNS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6.2 Experimental Procedure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6.2.1 Materials . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6.2.2 Welding Processes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6.2.3 Localized Corrosion Testing . . . . . . . . . . . . . . . . . . . . . . . . . . . .

61 61 62 62 63 63

29 29 31 32 33 34 34 34 36 36 38 38

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6.3 Behavior of Blowhole Generation in the Weld Metal . . . . . . . . . . . . . . 6.4 Solidification Mode of Weld Metal and Its Pitting Corrosion Resistance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6.5 Behavior of Cr Nitride Precipitation . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6.6 Localized Corrosion Resistance of HNS Welded Joints . . . . . . . . . . . . 6.7 Mechanism of Maintaining Corrosion Resistance of Weld Metal . . . 6.8 Conclusions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

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7 Application of HNS to PEFC Bipolar Plate . . . . . . . . . . . . . . . . . . . . . . . . 7.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7.2 Screening in PEFC Environment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7.2.1 Real PEFC Environment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7.2.2 Simulated PEFC Environment . . . . . . . . . . . . . . . . . . . . . . . . . . 7.3 Ni-Saving HNS Bipolar Plate . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7.3.1 Single-Cell Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7.3.2 XPS Analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7.3.3 TEM Observation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7.3.4 STEM Observation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7.4 Ni-Free HNS Bipolar Plate . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7.4.1 Polarization Measurements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7.4.2 ICR Measurement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7.4.3 XPS Depth Profiles . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7.4.4 Single-Cell Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7.4.5 TiN-SBR Hybrid-Coated Ni-Free HNS Bipolar Plate . . . . . . . 7.5 Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

71 71 77 77 78 80 81 82 85 87 88 88 90 91 94 95 96 97

66 66 67 68 69 69

List of Figures

Fig. 2.1

Fig. 2.2 Fig. 2.3

Fig. 3.1 Fig. 3.2 Fig. 3.3 Fig. 3.4 Fig. 3.5 Fig. 3.6 Fig. 3.7 Fig. 3.8 Fig. 3.9 Fig. 3.10 Fig. 3.11 Fig. 4.1 Fig. 4.2 Fig. 4.3

Effect of alloying elements on the nitrogen solubility of iron-based alloy under 1atm, 1600 Celsius [2]: ©1968 AIME . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Nitrogen solubility of Fe-Cr alloy under 1 ata. in the equilibrium state [3]: ©2022 IAEA . . . . . . . . . . . . . . . . . . . . Relation between time for full nitrogen absorption and material size in SUS304 stainless steel plate and wire [16]: ©2004 ISIJ . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Phase diagram of HNS calculated by thermodynamic method. Ref. [1]: ©2004 Marcel Dekker Inc. . . . . . . . . . . . . . . . . . . . . . . . . Schematic diagram of pressurized electroslag re-melting furnace. Ref. [1]: ©2004 Marcel Dekker Inc. . . . . . . . . . . . . . . . . . Schematic principle of pressurized electroslag re-melting method. Ref. [1]: ©2004 Marcel Dekker Inc. . . . . . . . . . . . . . . . . . Appearance of pressurized ESR furnace developed by NIMS . . . . Behavior of chemical components in the metal pool of ESR ingots . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . An example of longitudinal macroscopic structure of ϕ90 mm of a P-ESR ingot . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . An example of primary electrode used for a ESR test . . . . . . . . . . Relation between slag components (Nx) and electric conductivity (K) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Relation between pressure and nitrogen solubility of SUS316L . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Oxygen potential equivalent to C, Si, Cr, Al components . . . . . . . Gibbs’ free energy of various Ca compounds . . . . . . . . . . . . . . . . . Nominal stress–strain curves of HNS. Ref. [2]: ©2007 Trans. Tech. Publications Ltd . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Mechanical properties of HNS. Ref. [3]: ©2004 Marcel Dekker Inc . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Temperature dependence of mechanical properties of HNS . . . . .

7 8

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Fig. 4.4

Fig. 4.5

Fig. 4.6 Fig. 4.7 Fig. 4.8 Fig. 4.9

Fig. 4.10 Fig. 4.11

Fig. 5.1

Fig. 5.2

Fig. 5.3

Fig. 5.4

Fig. 5.5

Fig. 5.6 Fig. 5.7

List of Figures

Load–elongation curves of HNS in a wide range of wide temperature. Ref. [4]: ©2015 Springer-Verlag Berlin Heidelberg . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Effects of holding time on Charpy test and the area fraction of brittle fracture. Ref. [2]: ©2007 Trans. Tech. Publications Ltd . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Charpy impact test results of 23% Cr–4% Ni–2% Mo–1% N steel fabricated by pressurized ESR method . . . . . . . . . . . . . . . . . . Ductile to brittle transition behavior in austenitic steels. Ref. [6]: ©1998 Elsevier . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Typical TEM micrograph of deformed HNS (after 20% cold rolled). Ref. [4]: ©2015 Springer-Verlag Berlin Heidelberg . . . . . HNS thin wire of 50 μm in diameter a HNS, b human hair with about 100 μm in diameter. Ref. [4]: ©2015 Springer-Verlag Berlin Heidelberg . . . . . . . . . . . . . . . . . . . . . . . . . . HNS thin plate of 80–100 μm in thickness. Ref. [4]: ©2015 Springer-Verlag Berlin Heidelberg . . . . . . . . . . . . . . . . . . . . . . . . . . HNS thin wall tubes of 100 μm in thickness, and 1000–1200 mm in length. Ref. [4]: ©2015 Springer-Verlag Berlin Heidelberg . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Effect of composition on the critical potential for pitting corrosion of nitrogen-bearing stainless steel in artificial seawater at the temperature of 45 °C. Ref. [1]: ©2004 GRIPS media GmbH . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Effect of molybdenum content on pitting corrosion potential of nitrogen-bearing stainless steel in artificial seawater at the temperature of 45 °C. Ref. [1]: ©2004 GRIPS media GmbH . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Relationship between crevice corrosion resistance equivalent (%Cr + 3*%Mo + 10*%N in mass%) and crevice corrosion potential of nitrogen-bearing stainless steel in artificial seawater at the temperature of 35 °C. Ref. [1]: ©2004 GRIPS media GmbH . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Effect of molybdenum content on crevice corrosion potential of nitrogen-bearing stainless steel in artificial seawater at the temperature of 35 °C. Ref. [1]: ©2004 GRIPS media GmbH . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Effect of composition on the critical temperatures for pitting corrosion and for crevice corrosion. Ref. [6]: ©2003 vdf Hochschulverlag AG an der ETH Zurich . . . . . . . . . . . . . . . . . . . . Multi-crevice specimen assembly of HNS. Ref. [9]: ©2015 Springer-Verlag Berlin Heidelberg . . . . . . . . . . . . . . . . . . . . . . . . . . Specimen-set-up for the field test in the sea. Ref. [9]: ©2015 Springer-Verlag Berlin Heidelberg . . . . . . . . . . . . . . . . . . . . . . . . . .

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43 44 44 45

46 46

47

50

50

51

51

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List of Figures

Fig. 5.8 Fig. 5.9

Fig. 5.10

Fig. 6.1 Fig. 6.2

Fig. 6.3 Fig. 6.4

Fig. 6.5

Fig. 6.6 Fig. 7.1 Fig. 7.2

Fig. 7.3

Fig. 7.4

Fig. 7.5

The appearance of specimen-set-up collection after the period of 8 years. Ref. [9]: ©2015 Springer-Verlag Berlin Heidelberg . . . The appearances of specimens tested for 8 years: a as collection, b after removing bio-film. Ref. [9]: ©2015 Springer-Verlag Berlin Heidelberg . . . . . . . . . . . . . . . . . . . . . . . . . . ESCA spectra in terms of N 1s recorded before (as polished) and after crevice corrosion test (corroded and non-corroded areas). Ref. [9]: ©2015 Springer-Verlag Berlin Heidelberg . . . . . . Cross-section macrographs of GTAW beads. Ref. [2], ©2002 Japan Welding Society . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Relation between dilution rate and blowhole inclusion in weld metal compared with predicted value of N content and N solubility in molten metal. Ref. [2], ©2002 Japan Welding Society . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Cross-section macrographs of CO2 laser and plasma welded beads . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Time–temperature–precipitation diagram compared with estimated curves. Ref. [3], ©2002 Japan Welding Society . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Critical pitting corrosion temperature and critical crevice corrosion potential of welded joints. Ref. [3], ©2002 Japan Welding Society . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Comparison of the pitting potential of weld metals and parent metals. Ref. [2], ©2002 Japan Welding Society . . . . . . . . . . . . . . . Principle of PEFC (a) and schematic of i-V curve and losses of PEFC (b) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Cross-section of MEA (a), design layout [3] (b) and photograph (c) of the bipolar plate. The length of the white scale bar in (c) is 10 mm in length: ©2006 Elsevier . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Photographs of the stamped stainless steel bipolar plate. (a): [11], ©2006 Elsevier, (b): Reprinted from [12] with the permission from ©2021 The Japan Institute of Metals and Materials, (c) [13]: ©2010 Elsevier . . . . . . . . . . . . . Influence of corrosion progress on type 430 stainless steel bipolar plates: time variation of cell voltage (a), the equivalent circuit of the PEFC (b), cole-cole plots (c) and impedance parameters (d) [38]: ©2010 Elsevier . . . . . . . . . . . . . . . . . . . . . . . . Comparison of i-V characteristics of cells with type 316L stainless steel, Ni-saving HNS, and graphite bipolar plates at (a) initial state and (b) after 1,000 h of cell operation [50]: ©2012 Elsevier . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

xiii

56

56

57 64

65 65

67

68 69 73

74

75

79

82

xiv

Fig. 7.6

Fig. 7.7

Fig. 7.8 Fig. 7.9

Fig. 7.10

Fig. 7.11

Fig. 7.12

Fig. 7.13

Fig. 7.14

Fig. 7.15

Fig. 7.16

List of Figures

SEM images of the rib surfaces on (a) anodic side of type 316L stainless steel, (b) cathodic side of type 316L stainless steel, (c) anodic side of Ni-saving HNS, and (d) cathodic side of Ni-saving HNS after 1,000 h of cell operation. The scale bar indicates 10 μm [50]: ©2012 Elsevier . . . . . . . . . . . . . . . . . . . Cationic ratio of chromium versus iron oxide in the passive film based on XPS analysis for type 316L stainless steel and Ni-saving HNS after 1,000 h of cell operation [50]: ©2012 Elsevier . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Schematic of electrochemical reactions on stainless steel [50]: ©2012 Elsevier . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . TEM bright-field images of bipolar plate on the cathodic side after 1000 h of cell operation: a undamaged part for type 316L stainless steel and b the corresponding EDS spectrum; c damaged part for type 316L stainless steel and d the corresponding EDS spectrum; and e undamaged part for Ni-saving HNS, f the corresponding EDS spectrum [50]: ©2012 Elsevier . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . HAADF-STEM images (a: as-polished state, b: cathodic side after 1,000 h cell operation) of Ni-saving HNS [50]: ©2012 Elsevier . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . HAADF-STEM image (a) and EELS line profile (b) of Ni-saving HNS bipolar plate for the cathodic side after 1,000 h cell operation [51]: ©2012 Elsevier . . . . . . . . . . . . . . Anodic polarization curves for type 445 stainless steel and Ni-free HNS in deaerated SO4 2– + 2 ppm F– solutions at 353 K: a pH 2.3 and b pH 4.3 [35]: ©2009 Elsevier . . . . . . . . . Variation of anodic current density at 600 mV for type 445 stainless steel and Ni-free HNS in aerated 0.05 M SO4 2– + 2 ppm F– solutions at 353 K for 8 h: a pH 2.3 and b pH 4.3 [35]: ©2009 Elsevier . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ICR between stainless steel (type 445 stainless steel and Ni-free HNS) and carbon cloth GDL before and after polarization at 600 mV in 0.05 M SO4 2– + 2 ppm F– solutions at 353 K for 8 h: (a) pH 2.3 and (b) pH 4.3 [35]: ©2009 Elsevier . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . XPS depth profiles of type 445 stainless steel (a as-polished state, c pH 2.3 and e pH 4.3) and Ni-free HNS (b as-polished state, d pH 2.3 and f pH 4.3) in 0.05 M SO4 2– + 2 ppm F– solutions at 353 K for 8 h [35]: ©2009 Elsevier . . . . . . . . . . . . . . . Cell voltage for 1,000 h operation by applying a constant current of 0.5 A cm–2 (12.5 A) at 348 K [35]: ©2009 Elsevier . . .

83

84 85

86

88

89

90

91

92

93 94

List of Figures

Fig. 7.17

Fig. 7.18

Fig. 7.19

Metallurgical microscope images of the rib surfaces after 1000 h; a anodic side of the type 445 stainless steel, b cathodic side of the type 445 stainless steel, c anodic side of the Ni-free HNS and d cathodic side of the Ni-free HNS. The scale bar indicates 1.0 mm [35]: ©2009 Elsevier . . . . . . . . . . Change of anodic current density at 600 mV(SCE) for the TiN-SBR coated Ni-free HNS in aerated 0.05M SO4 2– (pH 2.3) + 2 ppm F– solutions at 353 K for 8 h (a) and ICR between TiN-SBR coated Ni-free HNS and carbon cloth GDL before and after polarization (b) [35]: ©2009 Elsevier . . . . . Comparison of initial i-V characteristics of as-polished Ni-free HNS and TiN-SBR coated Ni-free HNS bipolar plates employing single cells [35]: ©2009 Elsevier . . . . . . . . . . . .

xv

95

96

97

List of Tables

Table 2.1 Table 2.2 Table 3.1 Table 3.2 Table 3.3 Table 3.4 Table 3.5 Table 3.6 Table 3.7 Table 3.8 Table 3.9 Table 3.10 Table 3.11 Table 3.12 Table 4.1 Table 5.1

Table 6.1

The historical progress of high nitrogen steel production technology . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . The list of representative high nitrogen steels developed in the world (mass%) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Chemical compositions of commercially available FCrN (mass%) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Chemical compositions of primary electrode used for VIF melting (mass%) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Chemical compositions of P-ESR ingots (mass%) . . . . . . . . . . . . Nitrogen content of P-ESR ingots . . . . . . . . . . . . . . . . . . . . . . . . . Relation between nitrogen content of P-ESR ingots and pressure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Chemical compositions of FCrN after nitrization . . . . . . . . . . . . Chemical compositions of primary electrode for Ni-less 23Cr1Mo–1N steel . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Chemical compositions of Ni-less HNS ingot after melting by P-ESR method . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Results of inclusion survey in the middle part of P-ESR ingot based on JIS G 0555 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Al deoxidation test results by various slag compositions . . . . . . . Results of comparison data between designed values and empirical ones by Ca deoxidation tests . . . . . . . . . . . . . . . . . Chemical compositions of slag after Ca deoxidation tests by ESR (mass%) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Microstructure and tensile strength of HNS obtained in this study. Ref. [2]: ©2007 Trans. Tech. Publications Ltd . . . . . . . . . Results of analysis of seawater components at the field tests in the seawater. Ref. [9]: ©2015 Springer-Verlag Berlin Heidelberg . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Chemical compositions of base metals used (mass%). Ref. [2], ©2002 Japan Welding Society . . . . . . . . . . . . . . . . . . . . . . . .

6 6 21 25 26 27 28 28 28 30 33 33 37 38 40

55 62 xvii

xviii

Table 6.2 Table 6.3 Table 7.1 Table 7.2 Table 7.3 Table 7.4 Table 7.5 Table 7.6 Table 7.7

List of Tables

Chemical compositions welding consumables used (mass%). Ref. [2], ©2002 Japan Welding Society . . . . . . . . . . . . Welding conditions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Comparison of fuel cells . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Functions and requirements of bipolar plates . . . . . . . . . . . . . . . . Typical manufacturing methods of bipolar plates . . . . . . . . . . . . . An example of stainless steel bipolar plates . . . . . . . . . . . . . . . . . An example of the real PEFC environments . . . . . . . . . . . . . . . . . An example of the simulated PEFC environments [52]: ©1995 Springer Link . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Chemical composition of specimens (mass%) . . . . . . . . . . . . . . .

62 63 72 74 75 76 78 80 81

Chapter 1

Resource-Saving-Type High-Nitrogen Austenitic Stainless Steel

Since the addition of nitrogen to steel makes it brittle, it has long been discouraged to treat nitrogen as an alloying element. The first study on nitrogen addition was by Andrew [1], who aimed at improving strength, followed by that of Adcock [2] on the Fe–Cr system. Research in the 1930s then focused on the strength increase attributable to nitrogen addition. In the 1930 and 1940s, nitrogen was examined as an alternative to nickel as a stabilizing element in the austenitic phase owing to the depletion of nickel, used as a wartime material. Fresher and Kubisch showed for the first time that not only the mechanical properties but also the corrosion resistance improved by increasing the amount of nitrogen [3]. Since then, research in this field has become increasingly active since the work of Uhlig and White [4]. In the 1970s, since AOD (argon oxygen degassing) process was put into practical use, nitrogen addition using nitrogen gas has become easy. In this process, not only austenitic stainless steel with high nitrogen solubility but also nitrogen alloying into duplex stainless steel has been performed. It is also a great advantage that expensive Ni can be saved by combining nitrogen and manganese, and 18Cr-5Ni-8Mn-0.15 N was developed as a representative example; this steel grade shows higher strength and higher corrosion resistance than AISI304 stainless steel. The 18Cr-5Ni-8Mn stainless steel has been standardized as AISI202 by accumulating data in subsequent studies. Excellent reviews by Rashev [5] and Gavriljuk and Berns [6] have been published on the manufacturing and properties of high-nitrogen steels. In producing highnitrogen steel, the most important issue is how to dissolve nitrogen in the steel and retain it. To dissolve nitrogen in steel, Mo, Mn, Cr, V, Nb, and Ti are used to reduce the nitrogen activity and increase the solubility. V, Nb, and Ti are added to dissolve the nitride deposited during the heat treatment. The solubility of nitrogen in molten steel follows Sieverts’ rule. Therefore, the in-take of nitrogen from nitrogen gas under normal pressure into the steel is limited by Sieverts’ law, meaning that nitrogen can be introduced into the steel as an interstitial element or as a nitride exceeding the thermodynamic equilibrium condition. Incorporating nitrogen requires special dissolution techniques. © National Institute for Materials Science, Japan 2022 Y. Katada et al., Nickel-saving Type High Nitrogen Austenitic Stainless Steel, NIMS Monographs, https://doi.org/10.1007/978-4-431-56927-5_1

1

2

1 Resource-Saving-Type High-Nitrogen Austenitic Stainless Steel

Worldwide research on high-nitrogen steel has a long history and has been conducted very actively [7–19]. The past conferences held at Lille (1988), Aachen (1990), Kiev (1992), Kyoto (1995), Helsinki and Stockholm (1998), Chennai (2002), Zurich (2003), Ostend (2004), Jiuzhaigou Valley (2006), Moscow (2009), Chennai (2012), and Hamburg (2014) showed the extraordinary developments in HNS materials and their wide applications in many industrial sectors. High-nitrogen steels have been proven to possess excellent corrosion and mechanical properties combined with good wear and abrasion resistance. They are finding increasing applications in power plants, chemical process industries, transportation, oil, gas, and fertilizer industries, pulp and paper, food processing, civil construction, and so forth. The growing demand for successive conferences showed the importance of this new class of materials that have been emerging globally in the recent past for a variety of new applications. The present conference in this line also provides a forum for engineers, metallurgists, and scientists in academic, industrial, and research institutions to exchange their latest findings and update their professional knowledge for further developments. Research on high-nitrogen steel in Japan has become particularly active since the International Conference on High-Nitrogen Steel (HNS 1985) held in Kyoto. Powder metallurgy can provide materials with the highest strength, but since there is no deoxidizing step, it is difficult to reduce oxides and there was a limit to the improvement of corrosion resistance due to the presence of oxides. The nitrogen absorption method is the technology most likely to enter practical use with the aim of cost reduction, but the problem is suppressing the coarsening of crystal grains accompanying the nitrogen absorption treatment. The pressurized ESR method can create a bulk material with reduced impurities. An example of development research of high-nitrogen steel by the pressurized ESR method in Japan is the “Development of seawater-resistant stainless steel” project [20–23], which was started at the National Institute for Materials Science (NIMS) in 1997 as one of the Ultra Steel Projects. The purpose of the project is to develop ultra-stainless steel grade seawaterresistant, resource-saving high-nitrogen stainless steel by achieving a high degree of refining of materials without significantly increasing the alloying weight of Cr, Ni and Mo. To realize this project, a pressurized electroslag remelting (P-ESR) system was developed at NIMS for the first time in Japan. This apparatus can realize nitrogen addition and material purification, and high-nitrogen stainless steel was successfully melted without adding Mn, which causes impurities [20]. NIMS has investigated the applicability of high nitrogen steel to a metallic separator of fuel cells and its applicability to stents for biomedical applications using lowNi or Ni-free high-nitrogen stainless steel. Research on the applicability of Ni-free high nitrogen steel to the bio/medical field has already been reported [23]. High-nitrogen steel research in Japan was reorganized by the Japan Iron and Steel Institute Material Organization and Characteristics Subcommittee under the “Effectiveness of nitrogen on properties of steels” Study Group (2004–2007, chairperson: Y. Katada (NIMS)). More than 30 domestic industry, government, and academic organizations gathered, and energetic research activities were conducted [24]. The contents of this document are partial excerpts from the final report.

References

3

References 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12. 13. 14. 15. 16. 17. 18. 19. 20. 21. 22. 23.

24.

J.H. Andrew, J. Iron Steel Inst. 86(II), 210 (1912) F. Adcock, J. Iron Steel Inst. 114, 119–126 (1926) J. Fresher, Ch., Kubisch, Berg und Hüttenmänn. M. H. 108, 361–380 (1963) H.H. Uhlig, R.A. White, TASM 52, 830 (1960) T. Rashev, High nitrogen steels (Metallurgy under Pressure, Publishing House of Bulgarian Academy of Sciences, Sofia, 1995) V.G. Gavriljuk, H. Berns, High Nitrogen Steels: Structure, Properties, Manufacture Applications, Springer Science & Business Media (2013) Proceedings of 1st International Conference on High Nitrogen Steels 88, held in Lille, France (1988) Proceedings of 2nd International Conference on High Nitrogen Steels 90, Aachen, Germany (1990) Proceedings of 3rd International Conference on High Nitrogen Steels 93, Kiev, Ukraine (1993) Proceedings of 4th International Conference on High Nitrogen Steels 95, Kyoto, Japan (1995) Proceedings of 5th International Conference on High Nitrogen Steels 98, Espoo, Finland and Stockholm, Sweden (1998) Proceedings of 6th International Conference on High Nitrogen Steels 2002, Chennai, India, Transactions of Indian Institute of Metals, 55, 4–5 (2002) Proceedings of 7th International Conference on High Nitrogen Steels 2004, GRIPS Media GmbH (2004) Proceedings of 8th International Conference on High Nitrogen Steels 2006, Jiuzhaigou, Sichuan, China, Metallurgical Industry Press (2006) Proceedings of 1st International Conference on Interstitially Alloyed Steels, IAS 2008, Graduate Institute of Ferrous Technology, Pohang University of Science and Technology (2008) Proceedings of 10th International Conference on High Nitrogen Steels, HNS2009, Moscow, Russia, MISIS (2009) Proceedings of 11th International Conference on High Nitrogen Steels and Interstitial Alloys (HNS-2012), Chennai, India (2012) Proceedings of 12th International Conference on High Nitrogen Steels (HNS2014), Hamburg, Germany (2014) Proceedings of 13th International Conference on High Nitrogen Steels (HNS2020), to be held in 2020, Shanghai, China (2020) Y. Katada, M. Sagara, Y. Kobayashi, T. Kodama, Mater. Manuf. Proc. 19(1), 19–30 (2004) Y. Katada, N. Washizu, Met. Sci. Heat Treat. 47, 494–496 (2005) M. Sagara, Y. Katada, ISIJ Int. 43(5), 714–719 (2003) Y. Katada, T. Taguchi, Advances in Metallic Biomaterials, Springer Series in Biomaterials Science and Engineering 3, edited by M. Niinomi, et al., 125–156 (2015). https://doi.org/10. 1007/978-3-662-46836-4 Y. Katada, Advances in Steel Research on the Availability of Nitrogen, Final Division Report, Division of Microstructure and Properties of Materials, Board of Academic Society, ISIJ (2008) (in Japanese)

Chapter 2

Production of High Nitrogen Steel (HNS)

Here, the metallurgy of high-nitrogen steel (HNS) required to create HNS, including the effects of alloying elements on the solubility of nitrogen, and the method of calculating the solubility of nitrogen based on the alloying elements of the material are outlined. Various HNS manufacturing methods have been proposed, such as the solidphase nitrogen absorption method, powder metallurgy method, and pressurized ESR method. In this chapter, the solid-phase nitrogen absorption method and powder metallurgy methods of mechanical alloying (MA) and metal injection molding (MIM) are reviewed in terms of their characteristics.

2.1 Metallurgy of HNS Many studies on nitrogen solubility in liquid metals have been reported over the last half century. Table 2.1 shows the historical progress of HNS production technology [1]. Table 2.2 shows a list of representative high-nitrogen steels developed internationally [1]. Since the nitrogen solubility of pure iron is very low under atmospheric conditions, to enhance the nitrogen solubility in an Fe matrix, some specific elements that increase nitrogen solubility should be alloyed. Figure 2.1 shows the effects of alloying elements on nitrogen solubility of iron-based alloy under 1 atm and 1600 °C. Specific elements such as V, Nb, Cr, Ta, and Mn are effective in increasing the nitrogen solubility in steels [2]. The nitrogen solubility of Fe–Cr alloy under atmospheric conditions is widely used and given by the following equation Eq. 2.1 [3]. log[%N] = −518/T − 1.063 + 0.046[%Cr] − 0.00028[%Cr]2 + 0.02[%Mn] − 0.007[%Ni] − 0.048[%Si] + 0.12[%O] − 0.13[%C] + 0.011[%Mo] − 0.059[%P] − 0.007[%S] (2.1) © National Institute for Materials Science, Japan 2022 Y. Katada et al., Nickel-saving Type High Nitrogen Austenitic Stainless Steel, NIMS Monographs, https://doi.org/10.1007/978-4-431-56927-5_2

5

6

2 Production of High Nitrogen Steel (HNS)

Table 2.1 The historical progress of high nitrogen steel production technology Year

Fabrication technology/Facilities

1950s

Pressurized melting technology

1960s

Pressurized ESR Furnace (lab-scale, Böhler) Pressurized plasma melting furnace (Patton Research Institute) (1–25 tons)

1970s

Pressurized ESR furnace (1–2 tons, Böhler)

1980s

First mass production by pressurized ESR furnace (INTECO / LEYBOLD, 10–20 tons)

1990–2000s

PAR, ESRP, PESR etc. (10–20 tons)

Table 2.2 The list of representative high nitrogen steels developed in the world (mass%) Standards UNS / EN

Cr 19

0.42

0.07

19.06

0.57

VSG, Essen

Nicrofer3033

R20033

33

30

1.45

0.74

0.38

Krupp VDM

Nicrfer59521

2.4700 (EN)

20

58

20

0.16

0.09

Krupp VDM

15.5

–

1.02

–

0.38

S21600

20

7

–

9

Alloys P900

Cronidur30 Nitronic40

Ni

Mo

Mn

N

others

Si, C

Makers

VSG, Essen Armco

Cronifer1925

N08926

20

25

6.2

–

0.2

Krupp VDM

Cromanite

1.3840 (EN)

19

–

–

10

0.5

Columbus &

Nitrinox

–

24

–

0–4

20