Effect of Gap between Steel Sheet and Electrode on Resistance Spot Welding

If resistance spot welding (RSW) is conducted when there is a gap between a steel sheet and an unmovable electrode, the steel sheets are bended by a movable electrode, and the quality of RSW is influenced. Therefore, it is necessary to understand the effect of the gap on RSW. In this study, two high-tensile strength steel sheets were welded with the gap. In addition, cross-section observations and cross tension tests were conducted to verify the effect of the gap on weldability and joint strength. Consequently, two notable results were obtained. First, the observation indicated that deformation around the corona-bond was varied depending on the gap. Second, the cross tension tests showed that the gap decreased the joint strength even though the nugget was large enough. These result indicated that controlling the gap is important to ensure the quality of RSW.