Patent ID: 10933488

Abstract:
A resistance spot welding method able to form a welded joint having delayed fracture resistance, includes, in order, applying a pressing force P1 (kN) to the plurality of steel sheets by welding electrodes while supplying a supplied current I1 (kA), while applying the pressing force P1, supplying a current Ic (kA) during a cooling time tc (s), repeating two times or more a pressure force raising and lowering cycle of supplying a supplied current I2 (kA) to the welding electrodes while applying a pressing force P2 (kN) to the plurality of steel sheets by the welding electrodes during a pressing time tf (s), then immediately applying a pressing force P3 (kN) during a pressing time ti (s), applying the pressing force P2 during the pressing time tf, and releasing the pressing force and ending the supply of current, satisfying 0≤Ic<I1, 0.3≤I2/I1<1.0, P2/P1≥2, tf≤0.2, P3<P2, and ti≤0.2.