Modeling of Resistance Spot Weld Nugget Growth -Applications for the Automotive Industry

The weld nugget in resistance spot welding of stainless 347 steel was found, using the finite element method, initiating at a distance from the electrode center in a ring shape. The ring-like weld nugget expands inwards and outwards during the welding cycles. The welding current, electrode pressure and hold time affected the thermomechanical interactions of the welding process and changed the final nugget geometry. As a result of spot welding of unequal thickness workpieces, the weld nugget formed mostly in the thicker workpiece than in the thinner workpiece. When spot welding dissimilar materials, the weld nugget formed more in the workpiece of lower thermal conductivity or higher electrical resistivity.