Contact conditions on nugget development during resistance spot welding of Zn coated steel sheets using rounded tip electrodes

This paper investigates the influence of coating on the nugget development during resistance spot welding of Zn coated steel sheets using rounded tip electrodes. The study relies on an experimental observation of zinc behaviour coupled with a numerical Electro-Thermo-Metallurgical–Mechanical analysis. The electro-thermal contact surface enlargement due to zinc ejection at sheet/sheet and electrode/sheet interfaces is found to have a negligible effect on the nugget development. The numerical analysis shows that the dispersion on the efficient weld size, attributable to the zinc effect, is below 10%.