## 3 Results and Discussions  
According to the data obtained by the StructureExpert Weld integrated software, the values for welding penetration and weld bead width were extracted. In Figure 5, it is \begin{table}
\begin{tabular}{c c c c c} \hline \hline \multirow{2}{*}{**Symbol**} & \multicolumn{2}{c}{**Welding**} & \multirow{2}{*}{**Level 1**} & \multirow{2}{*}{**Level 2**} & \multirow{2}{*}{**Level 3**} \\  & **Parameters** & & & \\ \hline A & Welding & & & \\ Voltage—V (V) & 20.8 & 23.8 & 25.6 \\ B & Travel Angle (\({}^{\circ}\)) & 33.0 & 36.0 & 53.0 \\ C & Welding & & & \\ Current—I (A) & 180.0 & 200.0 & 214.0 \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Welding process parameters and their levels. \begin{table}
\begin{tabular}{c c c c} \hline \hline \multicolumn{4}{c}{**Control Factor**} \\ \hline
**Test** & **A** & **B** & **C** \\ \hline
2 & 1 & 2 & 2 \\
3 & 1 & 3 & 3 \\
4 & 2 & 1 & 2 \\
5 & 2 & 2 & 3 \\
6 & 2 & 3 & 1 \\
7 & 3 & 1 & 3 \\
8 & 3 & 2 & 1 \\
9 & 3 & 3 & 2 \\ \hline \hline \end{tabular}
\end{table} 
Table 2: Experimental layout using the L9 orthogonal array. possible to show an illustration of macrographic images obtained from different samples. On top left is represented schematically a weld bead with the main geometric parameters, on C1, C2 and C3 are macrographic images from different samples. The tests were performed twice in each configuration. The summary of the resulting measurements for the experiment, represented in Figure 5, are shown in Table 3. Evaluating the measurements implemented for all experimental tests, an average value of 0.82 mm and 4.50 mm was obtained for the penetration and width of the weld bead, respectively. Furthermore, the correlation between the welding features of different cuts for the same weld are shown in Figure 6. We can find an adequate correlation in most cases. However, as expected, some outliers and slight non-linear trends are appreciated. These anomalies are hypothetically due to the machine and process's usual variability. Since the measured parameters in Table 4 do not follow a Gaussian distribution, as they are defined as positive, the mean and standard deviation are reported only for informative purposes. The robust measures of central tendency and dispersion considered for the analysis are the median (m) and median of absolute differences (_MAD_) [36]. The _MAD_ is defined according to Equation (2):  
\[MAD=m(|x_{i}-m_{x}|)\]  
Figure 5: Photographic illustrations of a macrographic analysis with StructureExpert Weld integrated software. \begin{table}
\begin{tabular}{c c c c} \hline \hline  & \multicolumn{3}{c}{**Cuts**} \\  & **C1** & **C2** & **C3** \\ \hline Root penetration—\(f_{1}\) (mm) & 1.23 & 1.11 & 1.46 \\ Bead width—\(f_{\rm L}\) (mm) & 5.85 & 3.62 & 5.65 \\ \hline \hline \end{tabular}
\end{table} 
Table 3: Parameters observed by StructureExpert Weld software. To measure the variability, the coefficient of quartile variation (\(CQV\)) (Equation (3)) [37,38] is also employed, where \(Q_{25}\) and \(Q_{75}\) denote the 25 th and 75 th quantiles of the distribution:  
\[CQV=\frac{Q_{75}-Q_{25}}{Q_{75}+Q_{25}} \tag{3}\]  
Complementarily, the normalization of the IQR by the median (IQR/median) is also employed as a robust measurement of dispersion. The cut-off value for this statistic is