Abstract
The effect of projection height on nugget formation and growth has been examined using projections with the constant diameter, embossed on a cold rolling sheet of low carbon steel of 1 mm in thickness (SPCC).
Using the high projection, the splash during the collapse of projection occurs extensively under the low electrode force, and causes to decrease the tensile shear strength. Using the low projection, the current shunting occurs in the other part near the projection. A rate of occurrence of the current shunting in the weld specimens. is found to increase with the electrode force. This shunting also causes the tensile shear strength to decrease the value near the critical weld current.
Under the high electrode force, the bonding part like a torus is formed at the initial period of weld time by using high projections. The tensile shear strength is related to the nugget diameter and the saturated diameter of nugget depends only on the weld current above the critical current as a function of the cold collapsed area and the electrode force.
