Electrode wear in the resistance spot welding of galvanized steel sheet.

摘要

In the resistance spot welding process, copper-based electrodes both conduct current and deliver force. The resultant heat and pressure of the welding process causes wear that decreases the useable life of the electrode. The wear process is accelerated considerably when welding galvanized steel sheet as compared to bare steel sheet. Electrodes used to weld galvanized sheet experience higher temperatures, pressures, and chemical attack from the zinc coating. As a result, the electrode material softens, the electrode face enlarges, and brass alloy layers form on the electrode face. If these wear mechanisms can be circumvented, electrode life can be appreciably increased and the principle user of the spot welding process, the automotive industry, can recognize significant cost savings.; This problem has been investigated through metallurgical evaluation and interpretation of a variety of electrode technologies. Candidate electrodes were subjected to standard electrode life tests, after which the as-received and worn electrode samples were destructively evaluated.; Electrode softening was investigated through microhardness indentation. (Abstract shortened by UMI.)