Improvement of Process Robustness in Weld Bonding of Galvanized DP780 Steel

The development of the weld bonding process for lighter, stronger, and more cost-effective vehicle structures requires a detailed understanding of the process robustness (i.e., welding lobe, which is defined as the range of the welding current and time under a given electrode force in which an acceptable weld is produced) in weld bonding of steels. In this study, a variable electrode force and an orthogonal design-of-experiment approach were employed to widen the welding lobe in weld bonding of 1.6-mm-thick galvanized DP780 steel. It was found that the optimized variable electrode force not only significantly widened the weld lobe but minimized the weld expulsion. With application of a servo weld gun, weld bonding with a variable electrode force can be readily applied to vehicle assembly.