It is found that tensile shear load bearing capacity of
welded materials increased with increasing peak weld currents
(Fig. 5). The enhancement in tensile shearing load
bearing capacity of weldment with increasing of peak current
is primarily attributed to the enlargement of nugget
size. As known pressure on the electrodes is maintained
for a hold or forging time while the weld solidifies during
the processes of spot weld. When the current is switched
off (automatically) the weld solidifies under pressure. During
this period, stress hardening takes place in the welding
zone due to the rapid cooling of weld metal. Increasing
peak current or welding time and electrode force increases
deformation hardening so, the tensile shear strength of
weld nugget may increase [8].