Hello,
From my experience, the main problems in spot welding are: cracks, burning spots, incomplete fusion depending of the settings control, expulsion of fused metal.
When welding this thickness for aluminium alloy like 2024-T3 the suggested settings are:
- two electrode radius of 4" (with very well cooled electrodes)
- electrode force about 800 lbf (weld) and 2000lbf (forge)
- 42KA (weld current)
- 1 cycle of CO
- 1 cycle of HT
- 4 cycles of CD (current decay)
- 1 impulse
With this settings you will be able to have a good quality spot with a minimum shear strength of 435 lbf and a minimum spot diameter of 0.160".
Good luck and good welds!