# Research on Roughness and Microhardness of C45 Material Using High-Speed Machining
## 2 Materials and Methods
\begin{table}
\begin{tabular}{c c c c c c c c c c c c c c c c c c} \hline \hline \multicolumn{1}{c}{} & \multicolumn{4}{c}{\(\
u_{c}\) = 700 (m/min)} & \multicolumn{4}{c}{\(\
u_{c}\) = 1400 (m/min)} & \multicolumn{4}{c}{\(\
u_{c}\) = 2000 (m/min)} \\ \cline{2-19} \multicolumn{1}{c}{} & \multicolumn{4}{c}{**Before HSM**} & \multicolumn{4}{c}{**After HSM**} & \multicolumn{4}{c}{**Before HSM**} & \multicolumn{4}{c}{**After HSM**} & \multicolumn{4}{c}{**Before HSM**} & \multicolumn{4}{c}{**After HSM**} \\ \cline{2-19} \multicolumn{1}{c}{} & \multicolumn{4}{c}{\(a_{p}\) (mm)} & \multicolumn{4}{c}{\(a_{p}\) (mm)} & \multicolumn{4}{c}{\(a_{p}\) (mm)} & \multicolumn{4}{c}{\(a_{p}\) (mm)} & \multicolumn{4}{c}{\(a_{p}\) (mm)} & \multicolumn{4}{c}{\(a_{p}\) (mm)} & \multicolumn{4}{c}{\(a_{p}\) (mm)} \\ \cline{2-19} \multicolumn{1}{c}{} & \multicolumn{1}{c}{**0.5**} & \multicolumn{1}{c}{**1**} & \multicolumn{1}{c}{**0.5**} & \multicolumn{1}{c}{**1**} & \multicolumn{1}{c}{**1.5**} & \multicolumn{1}{c}{**0.5**} & \multicolumn{1}{c}{**1**} & \multicolumn{1}{c}{**1.5**} & \multicolumn{1}{c}{**0.5**} & \multicolumn{1}{c}{**1**} & \multicolumn{1}{c}{**1.5**} & \multicolumn{1}{c}{**0.5**} & \multicolumn{1}{c}{**1**} & \multicolumn{1}{c}{**1.5**} \\ \hline A & 198.2 & 261.8 & 218.4 & 210.1 & 206.0 & 212.7 & 245.8 & 179.0 & 210.7 & 187.1 & 215.6 & 175.2 & 181.9 & 764.4 & 224.0 & 221.3 & 624.7 & 303.3 \\ B & 201.3 & 177.2 & 322.8 & 205.2 & 262.1 & 207.5 & 225.4 & 168.3 & 208.5 & 193.3 & 162.7 & 219.1 & 172.5 & 279.3 & 199.3 & 215.0 & 270.3 & 222.5 \\ C & 213.0 & 183.7 & 192.5 & 203.5 & 217.3 & 200.1 & 218.4 & 187.9 & 228.7 & 208.8 & 185.4 & 210.3 & 210.1 & 210.6 & 210.2 & 217.8 & 204.7 & 240.2 \\ \hline \hline \end{tabular}
\end{table} 
Table 3: Results of microhardness. \begin{table}
\begin{tabular}{c c} \hline \hline \multicolumn{1}{c}{**Debth of Cut [mm]**} & \multicolumn{1}{c}{**Before HSM**} & \multicolumn{1}{c}{**After HSM**} & \multicolumn{1}{c}{**Chip**} \\ \hline  & & & & & & & & & & & \\
0.5 & & & & & & & & & & & \\ \end{tabular}
\end{table} 
Table 5: Machining values in the primary shear zone for the first alternative of high-speed machining (\(\
u_{c}\) 700 m/min, A, B, C, designation of measuring points for microhardness). When analyzing the wear of the cutting tool in the first alternative (Figure 11), balanced wear of the cutting edges of the tool and minimal displacement of the cutting edge in the direction of the back was observed. During the experiment, tool wear analysis was examined after 5 min of continuous cutting. A shallow groove formed on the front of the tool. During the analyses of the second alternative (Table 6), deformation in the cutting zone was observed in the metallographic sections. During the removal of the 1 mm thick layers, the tool was significantly damaged (Figure 12), and the quality of the machined surface was low. During the analysis of the third alternative, the mechanism of the initial deformation in the cutting zone before the cutting edge of the tool was also observed. Based on the obtained results (Table 7), it is possible to observe the elongation of the grains into the shape of fibers. Chip deformation does not have the same intensity. There is a periodicity of deformation, which results in a \"sawtooth\" profile of the back of the chip. Heavily deformed grains break in front of the cutting edge. The figure shows that in the braked layer in front of the cutting wedge, there is a significant (up to fourfold) increase in the hardness of the material. This indicates a significant strengthening. This layer thus assumes the function of a cutting wedge when removing chips. At high temperatures, said layer in the deformation field appears to be plastic. Slides in the chip have a periodic character. Their frequency probably depends on the cutting speed and the geometry of the tool. There was a higher reinforcement in the shear zone than in the middle of  
Figure 11: Cutting tool wear—the first alternative (magnification 500\(\times\), \(v_{c}\) = 700 m/min).