Increasing resistance spot welding quality in stainless steel used in white goods industry

In this study, AISI 304 quality austenitic stainless steel sheets (ASS) used in the white goods industry with a thickness of 0,6 mm were combined with resistance spot welding using two different electrode materials and three different welding parameters (time, current and electrode force). The microhardness and tensile strength values of the welded joints were measured and also the macro and microstructure investigations of the weld cores were made. A 20 kVA capacity programmable logic controller (PLC), a timer that works 50 Hz and current controlled resistance spot welding machine (RSW) were used for welding. Welds are made using CuCo2Be and CuCrZr electrodes with 6 mm diameter and 45º cut cone tips. Welds were made under uncooled and cooled conditions. Core morphology and microstructure examinations of welded samples were examined under an optical microscope. Vickers microhardness tests were performed under 100 g load in 10 seconds. Tensile test samples were prepared according to ASTM: E8M and maximum tensile loads were measured on a universal tester. Weld parameters that give maximum tensile strength were determined in different electrode and cooling conditions. The welding parameters that give the maximum tensile load value are 5.4 kA, 10 cycles and 2 bar electrode compression force for CuCrZr; 5.4 kA, 15 cycles and 4 bar electrode compression force for CuCo2Be. Using the cooling system increased the tensile strength in the welding studies using the CuCrZr electrode and decreased in the welding studies using the CuCo2Be electrode. Increasing welding current and welding time values in welded joints mostly increased weld core diameters and tensile strengths.