## 3 Results and Discussion
### Microstructure Investigation  
For easier analysis of the results, all microstructure images shown in this section (Figures 10 and 11) were acquired at the same magnification. Figure 9: Results of clad height measurement for 2 selected sets of process parameters: efficient set and low heat input set. Figure 11: SEM microstructure of multilayer structures with preheating (T\({}_{0}\): 320 \({}^{\circ}\)C): (**a**) Number of layers: 3, parameter set No. 1, (**b**) Number. of layers: 8, parameter set No. 7. Figure 10: SEM microstructure of single clades deposited with selected sets of process parameters: (**a**) set No. 1, without preheating (T\({}_{0}\): 0 \({}^{\circ}\)C), (**b**) set No. 7 without preheating (T\({}_{0}\): 0 \({}^{\circ}\)C), (**c**) set No. 1 with preheating (T\({}_{0}\): 320 \({}^{\circ}\)C), (**d**) set No. 7 with preheating (T\({}_{0}\): 320 \({}^{\circ}\)C). The microstructure analysis of single clads demonstrated significant differences for extreme process travel speeds: 5 mm/s and 15 mm/s (Figure 10a,b). In Figure 10a, two types of carbides were observed: the first is a discontinuous grid of carbides formed from melting and solidification, while the second shape is partially melted carbides that form clusters (red circles). On the sample prepared with a lower travel speed (Figure 10a), a discontinuous grid of carbides has formed at the prior austenite grain boundaries, but there are also areas without carbides visible. A little gas porosity can also be detected (yellow arrows). In contrast, for a higher travel speed (Figure 10b), a finer continuous grid of carbides was observed. In a much greater degree (compared to the lower travel speed), the grid of carbides formed at the boundaries of prior austenite grain boundaries. Due to the higher travel speed, the structure clearly shows areas with dendritic regions. In this sample, the highest number of small gas pores is present (yellow arrows). Moreover, the lack of carbide clusters indicates the complete dissolution of carbides during the melting of additional material. X-ray diffraction examination showed that the clad structure consists solely of martensite and carbides. No residual austenite was detected. The coarser microstructure in Figure 10a is the result of higher heat input compared to Figure 10b, in which the presence of fine dendrites was identified. Further investigations consisted of an analysis of the effect of preheating on the microstructure obtained for the clads (Figure 10c,d). Preheating for a lower travel speed caused the growth of matrix grains and thickening of the carbide grid, which was perceived as an eutectic-like structure (Figure 10c, red arrows). In comparison to the sample without preheating the substrate, no clusters of unmelted carbides were observed. A few little gas pores are visible (yellow arrows). However, for a higher travel speed (Figure 10d), a slightly finer microstructure was received, resulting in a considerably thinner grid of carbides with only one potential cluster (red circle). The presence of dendrites in the microstructure was preserved. In both cases, the martensitic structure is clearly visible. In this case, no gas pores were found (yellow arrows). Due to their submicrosize and number, the presence of micropores should not be an issue in ensuring the functional properties of remanufactured cutting tools, i.e., hardness. The CLWD multilayer process with high heat input leads to a microstructure similar to that obtained for single clads (Figure 10c). The only differences are a slightly larger structure and thicker eutectic precipitations (Figure 11a, red arrows). On the other hand, the low heat input process (Figure 11b) delivers a coarser dendritic structure compared to Figure 10d. In both samples, several micropores were detected (yellow arrows). Generally, the multilayer processes in both cases caused a change in the thermodynamic conditions, which resulted in an increase in the solidification time and growth of the obtained structures.