SOME INVESTIGATION INTO RESISTANCE SPOT WELDING ~,.s. OF STAINLESS STEEL SHEETS

Abstract

In the present investigation, the effect of major process parameters of resistance spot welding i.e. weld current, weld time and electrode force on the strength of joint has been studied under different stress condition for 0.5 mm thick austenitic stainless steel sheet. Weld quality was assessed by means of tensile-shear and fatigue test. In each case, separate tests were made for each variable . In each event, failure load was recorded. It was found that failure load increases with increase in weld current or weld time or electrode force during tensile - shear test. It is common recommendation that weld should be made just below initial .expulsion because expulsion welds are undesirable and weak. But it was found that weld strength improves under expulsion conditions due to considerable growth in weld nugget size. It was found that weld nugget size increases with increasing welding current and electrode force as well as electrode indentation also increases with increase in welding current. Fatigue test was performed to determine the fatigue life of the joint. Fatigue life was found out to be very low because of notch around the periphery of weld nugget between the sheets. Nugget hardness as well as electrode indentation at various welding parameters was also measured