The influence of double pulse on porosity formation in aluminum GMAW

Pulsed GMAW (P-GMAW) has been recognized as an efficient alternative for minimizing porosity in aluminum welding. The double-pulsed GMAW (DP-GMAW) technique is a variation of the pulsed GMAW technique, in which the pulsing current aimed to metal transfer control is overlapped by a thermal pulsation, which in turn means pool control (similar to pulsed GTAW). Despite some advantages claimed by this reasonably new technique, one could expect more porosity when compared with P-GMAW. Thus, in this work a comparative study on the performance of these techniques at different parameter combinations and conditions favorable to generate porosity is presented. Porosity quantification was assessed by gravimetric and radiographic procedures, while the pores were characterized by macrographic analysis. The results indicate that the DP-GMAW technique maintains the capability of porosity minimization credited to the conventional P-GMAW technique and its advantages can be better exploited in industrial applications.