Electrical resistance welding (Resistance Welding or RW in AWS terminology) is an autogenous pressure welding process in which the heat required to bring the surfaces to be welded locally to forging or melting temperature is provided by electrical resistance from the passage of a current through the area to be joined. Welding is accomplished without filler material. Resistance welding, compared with arc welding, has the advantage of having less severe thermal cycles, thus having a significantly smaller thermally altered zone than arc welding. On the other hand, resistance welding can only be performed on limited thicknesses (generally less than 3 mm, although with specially designed parameters and electrodes it can be up to 6 mm) and requires special and very expensive procedures to provide continuous joints (disk electrodes). By means of electric resistance welding, both overlap joints, in which welding is limited to small portions of the overlapping surfaces, and butt joints, in which welding extends to the entire contact surface of the workpieces, can be made. Resistance welding is used on a wide range of applications on carbon steels, galvanized sheets, stainless steels, aluminum alloys, copper alloys and titanium.