Fatigue behavior of resistance spot-welded unequal sheet thickness austenitic stainless steel

Abstract

This paper presents a comparative study on the fatigue strength of resistance spot-welded unequal and equal sheet thickness austenitic stainless steel. Lap joints of 3.0-1.0 mm and 1.0-1.0 mm thick austenitic stainless steel were made using the same resistance spot welding schedule with current, weld time and electrode force of 4.7 kA, 20 cycles and 6 kN respectively. The sinusoidal wave form with a constant stress amplitude was selected in the fatigue tests whereas the stress ratio and frequency used were 0.1 and 8 Hz respectively. Fatigue strength and tensile-shear load bearing capacity of 3.0-1.0 mm joint were higher than that of 1.0-1.0 mm joint, although its nugget diameter was smaller. The joint stiffness was the controlling factor of the fatigue strength of resistance spot-welded unequal sheet thickness austenitic stainless steel.