Surface lubrication influence on electrode degradation during resistance spot welding of hot dip galvanized steel sheets

The material uptake mechanism of a resistance spot welding electrode is presented for two selected surface conditions of hot-dip galvanized steel sheets, i.e., lubricated and non-lubricated. The evolution of material deposition varies according to the different surface states. Spot welding of lubricated sheet results in a more uniform and reduced alloyed material uptake that deposits on the welding electrode cap. Accordingly, the low deposition of material on the electrode surface enhances the weldability of hot-dip galvanized steel sheets. A reproducible current flow and a stable energy input is thus ensured along the electrode cap surface during resistance spot welding. Furthermore, lubrication leads to a considerably reduced sticking of welding electrodes.