166 Prakt. Met. Sonderband 52 (2018) 
investigate possible influences of locally varying chemical composition caused by 
segregation on the deformation. 
2. EXPERIMENTAL 
The investigations were carried out on a high Mn-alloyed austenitic steel. For the 
characterization of the deformation lines around a Vickers hardness indent, the sample 
preparation was conducted by an ion slice cross section. About -30 um were removed by 
ion milling in order to avoid influences from mechanically polished surface zones. 
Figure 1 shows the Vickers hardness (HV1) indent in a grain on the ion-sliced area. The 
deformation structures around the hardness indent were investigated by means of scanning 
electron microscopy (SEM) (Auriga 40, Zeiss SMT) and electron backscatter diffraction 
(EBSD, Hikari Super Camera, EDAX) with a step size of 70 nm. The evaluation of the EBSD- 
data was conducted with the software OIM. In addition, energy dispersive X-ray 
spectroscopy (EDX, Apollo XPP, EDAX) investigations were performed in order to study 
segregation and possible related effects on the deformation mechanism. 
MA i 
100 pm 
Figure 1: SEM image of the ion slice cross section on the sample edge and hardness 
indent. 
3. RESULTS AND DISCUSSION 
3.1. Characterization of deformation structures 
The hardness indent is shown in Figure 2a. A symmetric indent could not be achieved, 
because this would require a very precise alignment of the indenter relative to the ion milled 
surface and a compensation of the asymmetric elastic deformation of the edge. 
Nevertheless, it is possible to conclude on the deformation mechanisms as shown in the 
following. Figure 2b shows a higher magnification SEM image of the hardness indent, which 
is surrounded by deformation structures in form of lines, which have formed surface steps . 
(Figure 2c). Prominent lines of the deformation structure are marked in Figure 2d and have Sar 
been used for further analysis of the deformation structure. m So 
EBSD measurements (Figure 3a) show that the hardness indent was placed in a grain with hey 
a surface orientation close to (101) (10° tilt angle). But even at higher magnifications (Figure Les 
3b) EBSD measurements did not reveal any orientation change in the vicinity of the steps. ie 
Thus, the visible deformation lines are ascribed to dislocation slip, as twins would cause an how 
orientation change. Tod