Resistance Spot Weldability and Electrode Wear Mechanisms of ZnNI EG® Sheet Steel

This study, conducted on a range of coating weights and substrate thicknesses, shows that ZnNi EG® DQSK sheet has excellent resistance spot weldability. Electrode life is excellent for all coating weights and substrate thicknesses studied, with most tests having to be terminated without failure at 10,000 welds. Current range for these materials was found to be typical for coated sheet in this thickness range. Analyses of electrode wear rates show that coating weight does not affect wear, but that electrode wear is affected by substrate thickness, the thinnest substrate producing the highest wear rates. An examination of the electrode wear mechanisms which influence the excellent electrode endurance revealed that a unique dual layer of alloys is formed on the electrode face when welding ZnNi-coated sheet. These alloy layers appear to greatly inhibit electrode-face erosion and extend electrode life.