## 3 Discussion of Results
For the purpose of assessment of the applied technology of welding influence on impact toughness and mechanical reaction during the fracture, the comparison was made of related fracture energy values obtained from the test samples that contain discussed MMA/MAG and MIG/MAG welds with notches on the face and root sides, positioned in different zones of the weld. Experimentally obtained  
Figure 6: Distribution and microstructure of the MIG/MAG samples: (**a**) the non-erosive zone of the root pass weld metal and coarse grain HAZ: bainite; (**b**) the weld metal and HAZ transient: bainite without acicular tendency. values of the fracture energy of the test samples with a notch on the face side of considered welds are presented in Figure 7, while for the test samples with a notch on the root side, they are shown in Figure 8.  
The comparative analysis of experimentally obtained fractureenergyvalues (forthe impact toughness testing) of samples with a notch on the face side of the MMA/MAG and MIG/MAG welds can be done based on diagrams presented in Figure 7. Experimentally obtained fracture energy of the test samples with a notch along the axis at the face side of the weld, made by the MMA/MAG and MIG/MAG procedures, were approximately the same, whichimbies that the welding procedure didnot impact the fracture energy of this type of sample. Due to the fact that the filling passes of both considered welds were done in the completely same way, it can be concluded that the filling passes had a dominant impact on the fracture energy values of the samples with a notch along the axis on the face side of the welded joint. Based on the diagram, presented in Figure 7, it can be concluded that the fracture energy for samples with a notch in the fusion zone was higher for the MMA/MAG welding procedures, which can be related to obtaining better penetration of the fusion zone and geometry of the weld groove. If the fracture energy is taken as a criterion for samples with a notch in the HAZ, the advantage is on the side of the MMA/MAG welding procedure. The fracture energy of test samples with a notch on the face side in specific zones of the MMA/MAG and MIG/MAG welds were approximately the same with insignificant discrepancies. The fracture  
Figure 8: Energy of the test samples with a notch on the side of the root pass of the welds. Figure 7: Energy of the test samples with a notch on the face side of the welds. energy that was experimentally measured on samples with a notch on the face side in the fusion zone of the MMA/MAG weld were higher than values corresponding to the MIG/MAG welding. Such a distribution of energy along different zones on the face side of the welds indicated that from this aspect, the MMA/MAG procedure provided favorable mechanical characteristics. Due to the fact that the two considered welding procedures (MMA/MAG and MIG/MAG) differed by technology applied for the root pass, it can be concluded that those technologies had minimal influence on the fracture energy distribution for samples with a notch on the face side. Experimentally obtained values of the fracture energy of samples with a notch on the side of the root pass of the MMA/MAG and MIG/MAG welds are presented in Figure 8. The fracture energy of samples with a notch along the axis of the welded joint on the root side was slightly higher for the MMA/MAG welding. This fact can be linked with the influence of applied technology for the root pass. The fracture energy of samples with a notch in the fusion zone and in the HAZ was higher for the MMA/MAG welding. Both considered technologies for the root pass were adequate from the aspect of the fracture energy (Figure 8). The comparative analysis of experimentally obtained fracture energies indicated that the MMA/MAG welding provided some favorable mechanical characteristics. The presented results of the fracture energy were completely in correlation with prior existing microstructure states, as well as with the corresponding microhardness values.