A Comparison of the Resistance Spot Weldability of Bare, Hot-Dipped, Galvannealed, and Electrogalvanized DQSK Sheet Steels

The spot weldability of various zinc-coated sheet steels was examined using several procedures and criteria. Current range testing indicated that increasing coating weight and average dynamic resistance widens current range. Electrode life testing showed that electrode life is affected by coating composition. In this study, the choice of the material with the widest current range was test procedure dependent. Based on one procedure, the hot-dipped galvanized sheet had the widest current range. The alternate procedure indicated that both the hot-dipped and the galvannealed materials exhibited superior current range. In general, the longest electrode lives were associated with the electrogalvanized and the galvannealed sheet, with their relative performance dependent upon the nugget diameter chosen to signify end of life. A significant amount of scatter in test results was observed which appears to be linked to electrode face variability Introduced by inconsistent electrode wear, requiring that multiple tests be conducted in order to obtain an accurate picture of the spot weldability of coated materials.