## 3 Results and Discussions
\begin{table}
\begin{tabular}{c c c c c c c c c c c c} \hline \hline  & \multicolumn{4}{c}{**Weld Root Penetration**} & \multicolumn{4}{c}{**Weld Bead Width**} \\  & \multicolumn{2}{c}{**Experiment 1**} & \multicolumn{2}{c}{**Experiment 2**} & \multicolumn{4}{c}{**Experiment 1**} & \multicolumn{4}{c}{**Experiment 2**} \\
**Cut** & **1** & **2** & **3** & **1** & **2** & **3** & **1** & **2** & **3** & **1** & **2** & **3** \\ \hline Mean (mm) & 1.32 & 0.83 & 0.38 & 1.09 & 0.79 & 0.44 & 5.04 & 4.23 & 4.61 & 4.80 & 4.11 & 4.64 \\ Median (mm) & 1.33 & 0.76 & 0.41 & 1.10 & 0.75 & 0.36 & 5.02 & 4.10 & 4.42 & 4.68 & 4.26 & 4.56 \\ Std. Dev. (mm) & 0.13 & 0.38 & 0.17 & 0.24 & 0.34 & 0.43 & 0.47 & 1.38 & 0.88 & 0.75 & 1.10 & 0.98 \\ MAD (mm) & 0.06 & 0.37 & 0.14 & 0.21 & 0.32 & 0.17 & 0.41 & 1.21 & 0.41 & 0.80 & 0.76 & 0.88 \\ Range (mm) & 0.43 & 1.00 & 0.50 & 0.51 & 0.94 & 1.25 & 1.31 & 3.96 & 2.81 & 2.21 & 3.43 & 2.61 \\ IQR (mm) & 0.14 & 0.71 & 0.30 & 0.44 & 0.61 & 0.30 & 0.85 & 2.45 & 1.16 & 1.09 & 1.51 & 1.75 \\ IQR/Median & 0.10 & 0.93 & 0.73 & 0.40 & 0.81 & 0.83 & 0.17 & 0.60 & 0.26 & 0.23 & 0.35 & 0.38 \\ CQV & 0.05 & 0.40 & 0.39 & 0.20 & 0.37 & 0.52 & 0.08 & 0.28 & 0.12 & 0.11 & 0.18 & 0.19 \\ \hline \hline \end{tabular}
\end{table} 
Table 4: Summary of the results of the two measured features for the 9 specimens of the experiment 1 and the 9 specimens of experiment 2. Figure 6: Correlation matrix and plot between the different cuts for the same specimen within the experiment 1.  
usually defined at 30% (0.3) [39], and lower values imply a small variability on the data, thus, in the present study, there were no significant differences for the nine tests. When considering the median value of weld root penetration and bead width for each cut as nominal values, the computed deviation can be assessed for their normality. By means of a Robust Jarque-Bera [40] normality test implemented in the statistical software STAR (Statistics Tests for Analyzing of Residuals) [41], they fulfil the Gaussian hypothesis, with the exception of cut 3 of experiment 2 in relation to weld root penetration (\(p\)-value = 4.846 \(\times\) 10\({}^{-7}\)). Table 5 expands the previous analysis (Table 3) to consider the deviations from nominal values. As the median was considered the nominal value for the central tendency, the ratio IQR/median cannot be computed. In all cases, the CQV is greater or less than zero, so significant differences for the deviations in the nine tests for all cuts are found. Figure 6 shows the Correlation matrix and plot between the three cuts (1, 2 and 3) for the same specimen within the experiment 1. The CQV is a robust measure of relative dispersion, therefore, as stated in Figure 6, it can be highlighted that there is a significant variation of root penetration for all cuts, except Cut 1 of experiment 1. In relation to the weld bead width, only Cut 2 of experiment 1 has a significant dispersion in relation with the other 5 cuts. These exceptions have to do with the way the welding is done: the torch varies the angle along the weld and so the depth and width of the weld bead also varies. According to [PERSON] [42], the most important geometric characteristics for controlling the quality of a weld are weld penetration and bead width. In the graphs of Figures 7 and 8 it is possible to observe the penetration and width values of the weld bead change with the change of input parameters. In combinations 1, 2, 3, 4, 5, 6, and 8, it is verified that there was a good repeatability of the tests from the first to the second experiment. However, in combinations 7 and 9, the weld bead is not homogeneous along weld of the cord. In some parts of the weld bead occurred excessive weld penetration, while in other parts the weld pierced the tubes, and, in some cases, the welding was not strong enough.