*3.5. Macrographs*

Figure 10 shows cross-sections from the middle of the bead for both the standard GMAW and CW-GMAW. One notices that the middle cross-section of the standard GMAW has an acceptable morphology without discontinuities, while achieving suitable penetration in the root face. Conversely, incomplete penetration persists in CW-GMAW. Due to the cold wire feed rates, more mass was deposited in CW-GMAW, which caused a decrease in penetration. This accounts for the incomplete penetration. Another technicality in CW-GMAW is the presence of inclusions, most likely oxides, due to the increased level of titanium in the weld metal due to the cold wire feeding, as the same wire was used as electrode and cold wire.

The presence of inclusions points to the need for more careful grinding after the root to clean the silicates formed during welding pool solidification. Another feature that differs between the cross-sections is the quantity of passes to fill them out. Standard GMAW required three passes and CW-GMAW only two. Ultimately, the overall heat input in CW-GMAW was lower due this difference in number of passes.

**Figure 10.** Middle of the bead cross-section showing the final weld morphology: (**a**) standard GMAW; and (**b**) CW-GMAW. The arrows indicate discontinuities such as inclusions and incomplete fusion.

To mitigate incomplete fusion, two alternatives might be used: increase the current by means of wire feed speed to increase penetration, or decrease the root face height to facilitate higher penetration.
