## 3 Results and Discussion  
### Main Influencing Variables and Interactions  
Figures 7 and 8 show the normal probability plot of the residuals for the target variable width and depth, respectively. Figure 5: Comparison of a cut open HAZ (**a**) and a cut open specimen (**b**). Figure 6: Schematic representation for calculating the roving overlap within a specimen. It can be seen that the residuals for both response variables approximately follow a straight line and show no patterns. Only the depth shows a slight outlier in the lower left-hand corner, which is considered negligible. The residuals are, therefore, derived from a normally distributed population [25]. Table 6 shows the results of the significance analysis with the \(p\)-value for the main and interaction effects included in the model for the width of the HAZ. The first column lists the factors and interactions, the second column the associated effects, the third column the \(p\)-values and the fourth column the order of significance for the factors and interactions. All interactions not presented had a \(p\)-value > 0.05 and were, therefore, not significant. The magnitude of the calculated effects for the main effects was between 246.2 and 2247.3 \(\upmu\)m. The nozzle diameter (B) had the most significant impact on the width of the HAZ. On the other hand, the temperature of the additional heat source (F) played a minor role. A highly significant difference could only be demonstrated for the linear main effects, except for the temperature of the additional heat source and the interaction between the nozzle curvature and the nozzle diameter. This is also reflected in the magnitude of the effects of these. In addition, the \(p\)-value for \"blocks\" was 0.549, indicating no significant difference between the first and second repetition of the experiments. Thus, it can be assumed that the experimental conditions did not change much. Table 7 shows the results of the significance analysis for the main and interaction effects included in the model for the depth of the HAZ. Figure 8: Normal probability plot for the depth of the HAZ. Figure 7: Normal probability plot for the width of the HAZ. For depth, all unlisted interactions also had a \(p\)-value \(>\) 0.05 and were, therefore, insignificant. The magnitude of the calculated effects for the main effects as between 22.2 and 330.3 \(\upmu\)m. The impact on depth was, thus, significantly smaller than on the width. This is also reflected in the shape of the HAZ, which was significantly wider than deep for each specimen--see Figure 5. The nozzle diameter (B) also influenced the depth the most. Only the main influencing factors and the interaction (AB) between the nozzle curvature (A) and the nozzle diameter (B) had a highly significant influence on the depth. The temperature of the additional heat source (F) had no effect. The \(p\)-value of 0.226 for the blocks was significantly lower than for the width but was also insignificant. Therefore, there is no indication of a significant change in the environmental influences over the test period either. Considering the two tables on the width and depth of the HAZ, the following key statements on the main effects can be summarised: \begin{table}
\begin{tabular}{c c c c} \hline
**Factor** & **Effect (\(\upmu\)m)** & \(p\)**-Value** & **Significance** \\ \hline Block & - & 0.549 & - \\ A & \(-748.8\) & 0.000 & *** \\ B & \(2247.3\) & 0.000 & *** \\ C & \(-549.3\) & 0.000 & *** \\ AB & \(-658.1\) & 0.000 & *** \\ D & \(748.1\) & 0.000 & *** \\ E & \(-958.2\) & 0.000 & *** \\ F & \(246.2\) & 0.016 & * \\ BD & \(-145.2\) & 0.150 & - \\ AEF & \(-279.5\) & 0.006 & ** \\ BDF & \(-304.8\) & 0.003 & ** \\ BEF & \(-287.7\) & 0.005 & ** \\ DEF & \(-226.9\) & 0.026 & * \\ ACDF & \(-309.4\) & 0.003 & ** \\ ABCDE & \(-263.3\) & 0.010 & * \\ ABCDF & \(208.6\) & 0.040 & * \\ ABDEF & \(-218.9\) & 0.031 & * \\ \hline \end{tabular}
\end{table}