TWI Industrial Member Report Summary 132/1980
By R M Rivett
Work was carried out to determine the influence of parent metal composition and surface finish on the number of welds which can be made with a pair of electrodes when resistance welding 1mm 2117, 5182 and 6010 aluminium alloys in the as-received, scratch-brushed and chemically cleaned condition. It was established that electrode life was primarily governed by surface condition rather than parent metal composition.
Surface resistance was assessed using static surface resistance, dynamic instantaneous resistance and cyclogram techniques. Only results obtained using the latter techniques, which employed currents which were more representative of those used in resistance welding, gave correlation with weldability
and electrode life. When the dynamic instantaneous surface resistance was outside lower-and-upper limits (<50, >130 micro Ohms) electrode lives of less than 300 welds were obtained due to the occurrence of excessive weld splash. Within these limits electrode lives varied from 1000 to approximately 3500 welds.