The effect of pulsed cold-wire feeding on the performance of spray GMAW

The application of pulsed cold-wire (P-CW) feeding has been one of the new approaches for arc welding over the past years. Such technique applied to GTAW shows that it can influence the process performance. However, P-CW feeding in GMAW has not been explored yet. Thus, the current work aimed at introducing and evaluating the effects of P-CW on the performance of GMAW, particularly with the spray metal transfer. The P-CW pulsing frequency and the angle between the cold-wire and the plate were varied in bead-on-plate and V-groove weldments. The effects of the P-CW on the weld bead geometry and metallurgical texture were, then, examined through cross-sections. The metal transfer from the wire tip to the weld pool and the arc behavior during wire feeding were analyzed backed by high-speed imaging. A thermal camera was used to monitor the back of the plates to examine the heat behavior with both the P-CW and non-pulsed feeding conditions. On the one hand, the results revealed that, although the pulsation affects the arc and the electric signal behavior and the metal transfer, no sensitive influence could be noticed regarding the weld bead geometries. On the other hand, the pulsed cold-wire feeding interfered in the thermal profile outside the weld pool. For the highest frequency explored, regardless the feeding angle, less heat was transferred to the plate. The smaller heat input in these cases limited grain growth, reducing the coarse grain HAZ area and resulting in a more refined microstructure. Therefore, P-CW showed to interfere in the GMAW process performance.