Experimental simulation of surface pitting of degraded electrodes in resistance spot welding of aluminium alloys

A novel experimental technique, using specially designed electrodes (with machined annular and circular pits, and central cavities), was developed to simulate the effects of pitting morphology of the electrode tip face on weld nugget size and joint strength in resistance spot welding of aluminium alloys. Results of the experimental simulations indicate that the distribution of electrode contact areas and their alignment between top and bottom electrodes both affect weld quality. A complete understanding of the correlation between tip face features and weld nugget formation would require three-dimensional numerical modelling; this work has provided well organised experimental data in support of future modelling work.