The direct observation of surface martensite formation upon cooling to temperatures close to ambient in a heat treated AISI 301 stainless steel
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Date
Authors
Mukarati, T.W.
Mostert, Roelf Johannes
Siyasiya, Charles Witness
Journal Title
Journal ISSN
Volume Title
Publisher
IOP Publishing
Abstract
Martensitic transformation, either athermal or strain-induced, in metastable AISI 301
austenitic steel is of high technical interest as this facilitates manipulation of mechanical
properties. This work is part of a project aimed at identifying the influence of variables that
determine the athermal α′-martensitic transformation in this steel in order to ensure consistent
martensite formation and optimized mechanical properties. The influences of initial austenitic
grain size and surface concentrations of interstitial elements (C, N) on martensite start
temperature were investigated. The surface concentrations of both carbon and nitrogen were
decreased through decarburisation and the formation of martensite upon cooling from ambient
temperatures was directly observed using a cryogenic Scanning Electron Microscope (cryo-
SEM). It was found that martensite formed on the heat-treated surfaces at much higher
temperatures than that expected for AISI 301 steel. The observations were confirmed using
electron backscatter diffraction (EBSD). Other analytical techniques including glow-discharge
optical emission spectroscopy (GDOES), and Neutron Diffraction were carried out to explain
the observations.
Description
Keywords
Martensitic transformation, Steel, Glow-discharge optical emission spectroscopy (GDOES), Electron backscatter diffraction (EBSD), Austenite, Austenitic transformations, Martensite, Mechanical properties, Neutron diffraction, Scanning electron microscopy (SEM), Strain, Austenitic grain size, Direct observations, Interstitial elements, Martensite start temperature, Surface concentration, Austenitic stainless steel
Sustainable Development Goals
Citation
Mukarati, T.W., Mostert, R.J. & Siyasiya, C.W. 2018, 'The direct observation of surface martensite formation upon cooling to temperatures close to ambient in a heat treated AISI 301 stainless steel', IOP Conference Series : Materials Science and Engineering, vol. 430, no. 1, art. 12042, pp. 1-8.