Resistance welding
Welding coated steel sheets

This welding process comes in a variety of configurations, the most widespread of which is spot welding, the case of which is mainly covered here. However, brush welding and seam welding, which are also used on coated sheet metal, are also covered.

In resistance welding, unlike arc and laser welding, zinc does not vaporize under the effect of heat, as the weld zone is under pressure from the welding force applied by the electrodes. In resistance welding, the presence of coatings on welded sheets therefore does not generate porosity-type defects. On the other hand, other effects are felt, mainly :

• modification of electrical contact resistances, the main sources of Joule effect heat at the start of welding; this modification implies an adaptation of welding parameters;

• chemical attack...