The Effects of Electrode Force on the Mechanical Behaviour of Resistance Spot-Welded 5083-O Aluminium Alloy Joints

In this study, the effects of electrode force on the static and fatigue strength of spot welded joints of 5083-O aluminium alloy sheets were investigated. The thickness of the sheet joints was 1.5 mm. Tensile-shear joints with one spot weld were considered and three different load levels for electrode force were selected as 2500 N, 3000 N and 3500 N while the welding time and electric current were fixed during resistance spot welding process. Also, micro-structures and micro-hardness of cross-sectional area of the test samples were investigated. The results show that increasing the electrode force from 2500 N to 3000 N has no major impact on the nugget size and fatigue strength of the specimens, but increasing the electrode force from 3000 N to 3500 N, despite reducing in the diameter of the nuggets, increases the fatigue life of the joints significantly. The results also indicate that increasing the electrode force increases the life associated with the crack initiation phase of total fatigue lifetime.