This work has a purpose to evaluate the electrode wear behaviour and the distribution of hardness in a joint welded by resistance spot welding process. The lifetime of electrodes was evaluated by examination of the electrode caps after more than 2000 points with acceptable welds.
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This work has a purpose to evaluate the electrode wear behaviour and the distribution of hardness in a joint welded by resistance spot welding process. The lifetime of electrodes was evaluated by examination of the electrode caps after more than 2000 points with acceptable welds. A microstructural evaluation by optical (OM) and scanning electron microscopy (SEM) was carried out. The microstructure of welded joint is primarily composed of ferrite grains. The microhardness test results indicated a significant increase in hardness in the weld nugget, probably due to the formation of martensite in the fusion zone. The hardness results for the four welding parameters selected at the end of the useful lifetime of the electrode were lower in all regions. The methodology used for parameter selection has highlighted an optimal combination of 200kgf electrodes force and 9 cy welding time (cycles), where more weld points were obtained, thereby increasing the lifetime of the electrode. The cover electrode tends to form brass (Zn + Cu) on the indentation obtained after spot welding, subsequently reducing electrode life. The results indicate the importance of combining welding parameters to reduce the electrode wear.@en