RESISTANCE SPOT WELDING METHOD FOR HIGH-TENSILE STEEL PLATES, AND RESISTANCE SPOT WELDING JOINT

摘要

The purpose of the invention is to provide a resistance spot welding method, whereby high joint strength even with materials having high Ceq can be achieved when resistance spot welding a set of sheets including high-strength steel sheets. A resistance spot welding method for welding by holding a set of sheets comprising at least two overlapped steel sheets between a pair of welding electrodes, and conducting current therethrough while applying pressure. This resistance spot welding method is characterized by comprising, in the following order: a first conduction step in which a current (Im) [kA] is applied to form a nugget diameter (d) [mm] satisfying formula (1); a conduction pause step (A) which follows the first conduction step, and in which cooling is performed while applying pressure; and a second conduction step in which current is applied using current values in two stages. 3 × √tm <= d <= 6 × √tm (1), wherein tm is the thickness [mm] of the thinnest sheet among the at least two steel sheets.