Results show that the failure was occurred by tearing of
interstitial free steel sheet metals side of spot welded materials
in all condition. Fracture did not take place within the
weld interface of welded materials. In these materials, the
samples joined with 4 kA peak current resulted fracture
in button shape and the other samples joined with 7 and
9 kA peak current resulted fracture starting from outer
region of the HAZ of IF steel side of weldment. Results
confirmed that with increasing in energy input, the region
of failure shifts from the interface to the outer region of
HAZ.