Diagrams of Dynamic Recrystallization of Austenitic Stainless Steels with Nitrogen

Капуткина, Л. М.; Efimenko, S. P.; Добаткин, С. В.; Leschinskaya, E.M.; Panovko, V. M.; Kazakov, M.A.

doi:10.4028/www.scientific.net/msf.318-320.793

Cited by 4 publications

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“…Kaputkina et al (1998) showed that dynamic recrystallization of steel Cr 18Ni6Mn5N during hot rolling between 1100 and 900°C was distinctly retarded by increasing the N content from 0.13 to 0.38 mass%. 4.1 alloying is an essential prerequisite of HNS.…”

Section: Hot Workingmentioning

confidence: 99%

High Nitrogen Steels

Gavriljuk¹,

Berns²

1999

Engineering Materials

387

110

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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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Section: Hot Workingmentioning

confidence: 99%

High Nitrogen Steels

Gavriljuk¹,

Berns²

1999

Engineering Materials

387

110

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“…With suitable cold work and heat treatment, high manganese high nitrogen stainless steels have exhibited the highest combination of strength and fracture toughness of any material in the globe [1].Thus on one hand there is substitution of expensive nickel by nitrogen in austenitic structure and freedom from nickel toxicity and on the other hand production of steels with very attractive combination of properties such as very high strength coupled with non magnetic behavior which makes them suitable for high end applications such as heavy generator retaining rings and body implants. There is apparently no study reported on the industrial production of this grade through EAF-AOD-LRF-CC-Steckel mill route whereas on laboratory scale extensive studies have been carried out and very high strength & fracture toughness achieved [1].Austenitic stainless steels with increasing nitrogen contents have been reported to exhibit slower dynamic recovery, stronger temperature dependence of flow stress and increased susceptibility to surface cracking [2].Wang et al have reported [3] that hot workability of 18Cr18Mn0.5N high nitrogen steels is generally poor with surface cracking and mixed grain structure. They studied the flow curve and processing map as a function of temperatures and strain rates and suggested processing window in temperature range of 1050 0 C to 1200 0 C and strain rate range of 0.1/S to 1/S.…”

Section: Introductionmentioning

confidence: 99%

Production of High Nitrogen Stainless Steel X8CrMnN18-18 through EAF-AOD-LRF-CC-Steckel Mill Route and its Hot Deformation Study by Gleeble Thermomechanical Simulator

Patra¹,

Singhal²

2013

AMR

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High nitrogen containing austenitic stainless steel X8CrMnN18-18 exhibits attractive combination of high strength, toughness and corrosion resistance.This grade containing more than 5000 ppm of nitrogen was produced commercially through EAF-AOD-LRF-CC-Steckel mill route and its microstructure and mechanical properties were studied. Excellent combination of strength,ductility and toughness is achieved in the entire range of 6mm to 50mm thick hot rolled plates. Uniaxial compression tests were carried out to understand the hot deformation behavior by varying temperature and strain rate. Softening behavior during deformation was analyzed from flow stress strain curves and microstructural analysis. Dynamic recrystallization (DRX) behavior of the material was observed during thermo mechanical processing. Critical strain related to DRX and Avrami kinetics of DRX was calculated by analyzing the flow curve data. Microstructural characterization was done by optical microscopy and EBSD analysis. Extensive grain refinement can be achieved by thermo-mechanical processing controlled by DRX. Keywords: High nitrogen stainless steel, Strength and toughness, DRX, Grain refinement, TMCP

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“…Some of the high alloy HNS nevertheless suffer from a rather narrow window of workability and require frequent reheating during forging. The susceptibility to cracking is higher at the beginning of hot working; dynamic recrystallization (DRX) of HNS during hot rolling between 1100 and 900°C was distinctly retarded by increasing the N content from 0.13 to 0.38 mass% [3]. On the other hand, the susceptibility to cracking is enhanced by second phases, segregation and a high tri-axial stresses.…”

Section: Introductionmentioning

confidence: 99%

Study of Hot Formability of High Nitrogen Martensitic Stainless Steel

Mehtedi

2008

MSF

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Alloying high-chromium steels with Nitrogen leads to increase in strength, fatigue life and corrosion resistance, but reduce ductility and could induce cracks formation during forging. In order to address these problems, the hot working response of a high Nitrogen martensitic stainless steel (Fe-16.2%Cr-1.1%Mo-0.33%N-0.34%C) has been investigated by means of hot torsion tests up to rupture, in the temperature and strain rate ranges of 900-1200°C and 0.005-5 s-1 respectively. The peak stresses of the flow curves were related to strain rate (e&) and temperature (T) by the well known sinh equation. The ductility and the safe working conditions were presented in terms of processing map. The microstructure of the steel in the quenched state after deformation was analyzed by means of optical microscopy; the differences in term of morphology and distribution of the various constituents were discussed.

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Diagrams of Dynamic Recrystallization of Austenitic Stainless Steels with Nitrogen

Cited by 4 publications

References 0 publications

High Nitrogen Steels

High Nitrogen Steels

Production of High Nitrogen Stainless Steel X8CrMnN18-18 through EAF-AOD-LRF-CC-Steckel Mill Route and its Hot Deformation Study by Gleeble Thermomechanical Simulator

Study of Hot Formability of High Nitrogen Martensitic Stainless Steel

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