Effect of TiC coating on electrode tip surface on electrode degradation during resistance spot welding zinc coated steel

The effect of TiC coating on electrode tip surface on electrode degradation during resistance spot welding zinc coated steel was investigated by SEM, EDX and XRD. The results show that the electrode degradation mechanism is basically caused by wear due to the fracture of local welding between the electrode tip surface and zinc coated sheet steel happened at electrode surface and alloying between electrode and zinc on coated steel during resistance spot welding zinc coated steel. The service life of CuCrZr electrode with TiC coating (1200 welds) is 2.4 times of that of uncoated CuCrZr electrode (500 welds). The reason of the TiC coating increasing electrode service life is that the TiC particles contained in the coating deposits can stop local welding between the electrode tip surface and zinc coated sheet steel and decrease alloying between electrode and zinc on zinc coated steel during resistance spot welding zinc coated steel.