On the interstitial induced lattice inhomogeneities in nitrogen-expanded austenite

Abstract

Lattice inhomogeneities, i.e. nitrogen interstitial-induced hexagonal-close-packed martensite (HCP-εN) and shear bands, can form in face-centred cubic nitrogen-expanded austenite (FCC-γN) synthesised on Fe-Cr-Mn and Fe-Cr-Ni austenitic stainless steel (ASS) using triode-plasma nitriding (TPN). Homogenous elemental distribution between HCP-εN and FCC-γN supports the displacive shear transformation mechanism proposed for a high-Mn, low stacking fault energy ASS under nitrogen interstitial-induced deformation. While resulting from transformation-induced plasticity, HCP-εN exhibits similar lattice expansion behaviour to the parent FCC-γN. However, inhomogeneous elemental distributions in the shear bands formed in γN layers on a 400°C TPN-treated high-Ni ASS indicate local migration of substitutional elements.

Metadata

Item Type:	Article
Authors/Creators:	Tao, X. Qi, J. https://orcid.org/0000-0001-5235-0027 Rainforth, M. https://orcid.org/0000-0003-3898-0318 Matthews, A. Leyland, A. https://orcid.org/0000-0002-5569-7293
Copyright, Publisher and Additional Information:	© 2020 Acta Materialia Inc. Published by Elsevier Ltd. This is an author produced version of a paper subsequently published in Scripta Materialia. Uploaded in accordance with the publisher's self-archiving policy. Article available under the terms of the CC-BY-NC-ND licence (https://creativecommons.org/licenses/by-nc-nd/4.0/).
Keywords:	Nitriding; Expanded austenite; Shear banding; Martensitic phase transformation; High-resolution electron microscopy (HREM)
Dates:	Published: August 2020 Published (online): 3 May 2020 Accepted: 30 April 2020
Institution:	The University of Sheffield
Academic Units:	The University of Sheffield > Faculty of Engineering (Sheffield) > Department of Materials Science and Engineering (Sheffield)
Depositing User:	Symplectic Sheffield
Date Deposited:	21 May 2020 09:31
Last Modified:	03 May 2021 00:38
Status:	Published
Publisher:	Elsevier BV
Refereed:	Yes
Identification Number:	10.1016/j.scriptamat.2020.04.045
Open Archives Initiative ID (OAI ID):	oai:eprints.whiterose.ac.uk:161055

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On the interstitial induced lattice inhomogeneities in nitrogen-expanded austenite

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