Electrode

Electrode
The selection of an electrode to be used in GMAW is a complicated decision, as it depends on the process variation being used, the composition of the metal being welded, the joint design, and the material surface conditions. The choice of an electrode strongly influences the mechanical properties of the weld area, making it a key factor in weld quality. In general, it is desirable that the welded metal have mechanical properties similar to those of the base material, and that there be no discontinuities, such as porosity, within the weld. To achieve these goals in different materials using different GMAW variations, a wide variety of electrodes exist. All contain deoxidizing metals such as silicon, manganese, titanium, and aluminum in small percentages to help prevent oxygen porosity, and some contain denitriding metals such as titanium and zirconium to avoid nitrogen porosity.Depending on the process variation and base material being used, the diameters of the electrodes used in GMAW typically range from 0.7 to 2.4 mm (0.028–0.095 in), but can be as large as 4 mm (0.16 in). The smallest electrodes are associated with short-circuiting metal transfer, while the pulsed spray mode generally uses electrodes of at least 1.6 mm (0.06 in).