A mechanism of crack growth was investigated in resistance spot welds of mild
steel. The experiments in this study were designed to investigate the effects of the
electrode cap geometrieson fatigue life of the resistance spot weld specimens. Two
types of electrode cap geometries were used. These types are 4.8 mm and 6.3 mm
nose,used with the same shank in welding operations of 2mm mild steel plate. To
obtain the goal, operating factors were precisely controlled, especially the electrode
force and welding current of spot welds, to keep the same operating conditions while
changingthe electrode geometries. The life test results showed an improvement in the
fatigue life of resistance spot welds. The increment was 30% in heavy loads and 10%
in low loads based on tool geometry. The improvement in the fatigue life was
produced by reducing the diameter of the nose in the geometry of the tool.