| Summary: | The extensive application of automobile high-strength steel requires high welding strength. A composite ceramic-filled annular electrode is designed based on the concept of controlling heat distribution and changing the nugget-growth mode. DP980 high-strength steel sheets were resistance welded to explore the effect of the annular electrode, and a traditional resistance spot electrode was also used for comparative analysis. The formation and mechanical properties of the nugget were analyzed. The results show that the resistance annular welding formed an annular nugget whose plan view is similar to the end face of the electrode. The annular nugget had a smaller surface indentation depth than the spot-welded nugget. Under the same external diameter of the end face of the electrode, applying the annular electrode produced a nugget area larger than that produced by a traditional circular end face electrode, thereby providing higher tensile and peeling strengths within a larger welding process window. The numerical simulation results of resistance annular welding (RAW) indicated that no current passed in the ceramic filled area; a small annular liquid nugget formed at the initial stage, and then grew inward and outward simultaneously during the welding process. Keywords: Ceramic-centered annular electrode, Resistance welding, High strength steel
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