Prakt. Met. Sonderband 52 (2018) 165
Investigation of deformation mechanisms in an austenitic Mn-steel
by means of scanning electron microscopy and electron
backscatter diffraction
Carola Hahn, Marina Lukas, Gerald Ressel, Thomas Klein, Reinhold Ebner
Materials Center Leoben Forschung GmbH, Roseggerstrasse 12, 8700 Leoben, Austria
ABSTRACT
The aim of this work was to investigate the deformation mechanism in a higher alloyed
austenitic Mn-steel, because these steels can deform by twinning and/or slip. Deformation
by localized twinning or slip leads to formation of deformation structures on the surface,
which either are bundles of deformation twins or slip bands. Such deformation structures
around a standard Vickers hardness indent were investigated by means of scanning electron
microscopy and electron backscatter diffraction to study the active deformation mechanism.
Energy dispersive x-ray spectroscopy was conducted in order to study influences of
segregation on the deformation.
The main result of the investigations is that the deformation structures are formed by
dislocation slip in the (101)-orientation and that an influence of segregations in the alloy
composition on the deformation mechanism was not observed.
1. INTRODUCTION
Due to their extraordinary combination of strength, ductility and high work hardening ability,
austenitic Mn-steels have received much attention in recent years [1,2]. According to
literature, higher alloyed austenitic Mn-steels deform by twinning and/or slip [3-6].
Additionally, the prevailing deformation mechanism depends on the type of loading, e.g.
tension or compression, and the crystal orientation relative to the loading direction [7].
In single crystal Hadfield steel samples, Karaman et al. [6] found that twinning occurred as
deformation mechanism if the [111]-direction was deformed under tension or the
[001]-direction under compression. An orientation dependence of the active deformation
mechanism was also found by Wang et al. [8], who investigated the deformation structure
around nanoindents in copper single crystals in (001), (011)-, and (111)-surface orientation.
They observed a four-fold symmetry around the indent on the (001 oriented surface, a two-
fold symmetry for the (011)-oriented surface and a six-fold symmetry for the (111)-oriented
surface. They explained their observations by material displacement, which occurs out of
the studied surface plane and along the zone-axis formed of the primary {11 1}-slip planes
and the indented surface plane. Schmid factor calculations by Kang et al. [7] for the fce-
structure showed that slip is favored in grains with (101)- and (111)-orientation and twinning
for the (001)-orientation when the surface plane normal is parallel to the compression
direction.
To acquire a deeper understanding of the deformation of the investigated austenitic Mn-
steel, the deformation structures around a HV1 indent were investigated by scanning
electron microscopy (SEM) and electron back scattered diffraction (EBSD). Additionally,
energy dispersive x-ray spectroscopy (EDX) was carried out in the vicinity of the indent, to
