Structural AA5754 aluminium alloy in 2.0 mm gauge was used
to form a (2.0 mmþ2.0 mm) stack for the fundamental trials in
laboratory condition. Spot welded samples were produced on a
strip containing 11 welds with the 1st weld un-shunted. The
geometry of the strip is shown in Fig. 1. The welds were made
using Medium Frequency Direct Current (MFDC) welding equipment,
which is specified to meet the high current and force
requirements for RSW aluminium [10]. The electrodes used for
this study were made of copper–zirconium (0.2%) and supplied by
Luvata with the manufacturer’s code of MN 16Z64. A spherical
geometry (50 mm radius) electrode was chosen as this acts to
increase the weld current density at the start of the weld cycle.
Weld parameters were set to achieve a range of spot weld sizes
and qualities to evaluate the NDT capability.