## 3 Results of Experiments and Their Discussion
### EBSD Observations  
Figure 4 shows EBSD orientation maps of the selected samples and Figure 5 presents the calculated grain size distributions and evolution of the average grain size (area-based) on \(\varepsilon\). Note that as grains, only areas separated by high-angle grain boundaries (HAGB) (misorientation > 15\({}^{\circ}\)) were considered. The 15\({}^{\circ}\) misorientation threshold between low-angle and high-angle grain boundaries (LAGB, HAGB) is a typical value frequently used in the literature. The individual dislocations may be identified in LAGB but they cannot be in HAGB. The grains are discontinuously separated by HAGB. HAGB are entirely composed of lattice defects and DWs in motion usually cannot move through them. DWs can usually move (excluding a strongly textured matrix) in the grain interior only and LAGB in the form of dislocations only slow down their motion or/and reduce their free path of motion, which in turn makes lower magnitudes of the corresponding MBN pulses. The sample deformed only elastically (\(\varepsilon\) = 2.5%) consists of grains without any specific relation between their shape and the sample reference frame. An increase in deformation caused a gradual stretching of the grains in the direction of load. Consequently, the projection of some grains in the EBSD measurement plane increased and caused an apparent broadening of the grain size distribution (Figure 5a) and an increase in the average grain size (Figure 5b). Note that this increase is only related to the significant change in the grain shape, and real grain growth was not observed. The most pronounced increase in the average grain size occurred primarily above \(\varepsilon\) = 25%, when the plastic flow turned from a homogenous one into a non-homogeneous one, see Reference [12]. This significant change in the grain shape is important for MBN anisotropy, as discussed later. EBSD orientation maps shown in Figure 4 exhibit a gradual increase in colour variation inside grains with the increasing deformation. This is a manifestation of a growing amount of strain, which causes local rotation of the crystal orientation. Qualitative analysis of the EBSD data, focused mainly on the strain, can be performed using Kernel average misorientation (KAM). KAM expresses the average misorientation between a point and a ring of neighbouring points, in this study, 1 st neighbours. The misorientation limit is 5\({}^{\circ}\); therefore, only strain inside the grains and sub-grains is analysed, and KAM can be directly associated with the geometrically necessary dislocations which cause the corresponding lattice rotation. The resulting KAM maps of the selected samples are shown in Figure 6. A small and spatially limited increase in KAM has already been observed in the \(\varepsilon\) = 2.5% sample. A higher KAM angle was usually present in the vicinity of certain grain boundaries, which indicates the occurrence of microplasticity already in the elastic region. An increase in deformation to \(\varepsilon\) = 15% and, subsequently, to \(\varepsilon\) = 30%, resulted in a distinct increase in KAM, which qualitatively corresponds to an increase in area fraction of green/yellow pixels. From the macroscopic point of view, the increase in KAM was uniform, but significant local variation in KAM indicates that some areas were deformed more than others. A further increase in strain to \(\varepsilon\) = 40% resulted in a totally deformed microstructure with a negligible area fraction of unaffected regions. Figure 3: Orientation distribution functions in the \(\varphi_{1}=0^{\circ}\) (left) and \(\varphi_{2}=45^{\circ}\) (right), where \(\square\): rotation cubic, \(\lozenge\): \(\{111\}\)\(<\)\(123\)\(>\) and \(\bullet\): Goss texture components. (**a**) \(\varepsilon=2.5\%\), (**b**) \(\varepsilon=15\%\), (**c**) \(\varepsilon=30\%\), (**d**) \(\varepsilon=40\%\). Figure 4: EBSD orientation maps. Tensile direction is horizontal.