Study of Series Spot Welding (Part 1)

Series Spot Welding of Various Materials

Abstract

Shunting current and tensile shear strength in series spot welding of 18-8 stainless steel, aluminium and tinned plate were studied. Especially for shunting current the shunting current equation proposed for mild steel was discussed about above materials. Further, an indicator WC of shunting current has been derived and series spot weldabilities of other various materials are given using W_C.
As the result of experiment and consideration the following were concluded.
(1) Upper plate shunting current of stainless steel and aluminium are 0.3 and 0.9 times that of mild steel respectively but in aluminium the ratio I_l/I_u is large as compared with that of mild steel or stainless steel.
(2) Shunting current of tinned steel is 0.4 times that of steel, therefore good welding results are obtained in the series spot welding of tinned plate.
(3) Linear relationship exists between upper plate current of various materials and indicator of shunting current W_C=log pO³/pT² and magnitude of shunting current is expressed by this indicator.
(4) Using the indicator W_S given in equation (6) series spot weldabilities of various materials are obtained.