## 3 Results and Discussion  
### Influences of the Assisting Gas Type on Cutting Quality  
#### 3.1.1 Cutting Surface Topography  
Distinctions in the surface topographies between oxygen cuts and argon cuts were observed from both macro and micro views. Traditional striation topography could be observed on the cutting surface of the oxygen cuts. However, only layer topography was observed on the cutting surface of all argon cuts with different process parameters, as shown in Figures 2a and 3a. In the micro view, abundant micrometer particles and voids were formed on the surface of the oxygen cuts, as shown in Figure 2b; meanwhile, no particles or voids could be observed on the argon cuts, and the surfaces were smooth and compact at the micrometer scale, as shown in Figure 3b.  
\begin{table}
\begin{tabular}{c c c c c c c c c c} \hline \hline \multirow{2}{*}{**Cut \#**} & \multirow{2}{*}{\begin{tabular}{c} **Power** \\ **(\(P_{\text{pk}}\)) W** \\ \end{tabular} } & \multirow{2}{*}{\begin{tabular}{c} **Repetition** \\ **Rate** \\ **(\(f\)) Hz** \\ \end{tabular} } & \multirow{2}{*}{\begin{tabular}{c} **Pulse** \\ **Width** \\ **(\%\(\tau\)) ms** \\ \end{tabular} } & \multirow{2}{*}{\begin{tabular}{c} **Speed** \\ **(\(v\))** \\ **mm/s** \\ \end{tabular} } & \multirow{2}{*}{\begin{tabular}{c} **Cut \#** \\ **mm/s** \\ \end{tabular} } & \multirow{2}{*}{\begin{tabular}{c} **Power** \\ **(\(P_{\text{set}}\))** \\ \end{tabular} } & \multirow{2}{*}{\begin{tabular}{c} **Repetition** \\ **Rate** \\ **(\(\tau\)) Hz** \\ \end{tabular} } & \multirow{2}{*}{\
\begin{tabular}{c} **Pulse** \\ **Width** \\ **(\(\tau\)) ms** \\ \end{tabular} } & \multirow{2}{*}{
\begin{tabular}{c} **Speed** \\ **(\(v\))** \\ **mm/s** \\ \end{tabular} } \\ \hline
1 & 20 & 4500 & 0.12 & 4 & 13 & 17 & 6000 & 0.12 & 4 \\
2 & 20 & 5000 & 0.12 & 4 & 14 & 18 & 6000 & 0.12 & 4 \\
3 & 20 & 5500 & 0.12 & 4 & 15 & 19 & 6000 & 0.12 & 4 \\
4 & 20 & 6000 & 0.12 & 4 & 16 & 20 & 6000 & 0.12 & 4 \\
5 & 20 & 6500 & 0.12 & 4 & 17 & 21 & 6000 & 0.12 & 4 \\
6 & 20 & 7500 & 0.12 & 4 & 18 & 22 & 6000 & 0.12 & 4 \\
7 & 20 & 6000 & 0.09 & 4 & 19 & 20 & 6000 & 0.12 & 3 \\
8 & 20 & 6000 & 0.10 & 4 & 20 & 20 & 6000 & 0.12 & 3 \\
9 & 20 & 6000 & 0.11 & 4 & 21 & 20 & 6000 & 0.12 & 4 \\
10 & 20 & 6000 & 0.12 & 4 & 22 & 20 & 6000 & 0.12 & 4 \\
11 & 20 & 6000 & 0.13 & 4 & 23 & 20 & 6000 & 0.12 & 5 \\
12 & 20 & 6000 & 0.14 & 4 & 24 & 20 & 6000 & 0.12 & 5.5 \\ \hline \hline \end{tabular}
\end{table}
Table 2: Process parameters for Set A.  
\begin{table}
\begin{tabular}{c c c c c c c c c c} \hline \hline \multirow{2}{*}{**Cut \#**} & \multirow{2}{*}{\begin{tabular}{c} **Power** \\ **(\(P_{\text{pk}}\)) W** \\ \end{tabular} } & \multirow{2}{*}{\begin{tabular}{c} **Repetition** \\ **Rate** \\ **(\(f\)) Hz** \\ \end{tabular} } & \multirow{2}{*}{\begin{tabular}{c} **Pulse** \\ **Width** \\ **(\(\tau\)) ms** \\ \end{tabular} } & \multirow{2}{*}{\begin{tabular}{c} **Speed** \\ **(\(v\))** \\ **mm/s** \\ \end{tabular} } & \multirow{2}{*}{\begin{tabular}{c} **Cut \#** \\ **(\(P_{\text{set}}\))** \\ \end{tabular} } & \multirow{2}{*}{\begin{tabular}{c} **Repetition** \\ **Rate** \\ **(\(\tau\)) Hz** \\ \end{tabular} } & \multirow{2}{*}{\
\begin{tabular}{c} **Pulse** \\ **Width** \\ **(\(\tau\)) ms** \\ \end{tabular} } & \multirow{2}{*}{
\begin{tabular}{c} **Speed** \\ **(\(v\))** \\ **mm/s** \\ \end{tabular} } \\ \hline
1 & 30 & 4500 & 0.10 & 4 & 13 & 25 & 6000 & 0.10 & 4 \\
2 & 30 & 5000 & 0.10 & 4 & 14 & 27.5 & 6000 & 0.10 & 4 \\
3 & 30 & 5500 & 0.10 & 4 & 15 & 30 & 6000 & 0.10 & 4 \\
4 & 30 & 6000 & 0.10 & 4 & 16 & 32.5